A lot of knowledge taught at school is declarative knowledge.


Chimpanzee mother and baby


Drawing of Acheulean handaxe from Spain from front, back, side, and top profile


Stone tools from the  Paleolithic Period , also known as the Stone Age, are indicative of cognitive advancements throughout human evolutionary history.


" The Lion-man ", found in the   Hohlenstein-Stadel cave  of Germany's  Swabian Alb  and dated to 40,000 years ago, is associated with the  Aurignacian culture  and is the oldest known  anthropomorphic  animal figurine in the world.


Motor and sensory areas of the cerebral cortex; dashed areas shown are commonly left hemisphere dominant.


Correlations between mental tests


An illustration of Spearman's two-factor intelligence theory. Each small oval is a hypothetical mental test. The blue areas correspond to test-specific variance ( s ), while the purple areas represent the variance attributed to  g .


An illustration of  John B. Carroll 's  three stratum theory , an influential contemporary model of cognitive abilities. The broad abilities recognized by the model are fluid intelligence (Gf), crystallized intelligence (Gc), general memory and learning (Gy), broad visual perception (Gv), broad auditory perception (Gu), broad retrieval ability (Gr), broad cognitive speediness (Gs), and processing speed (Gt). Carroll regarded the broad abilities as different "flavors" of  g .


An illustration of the  Jensen box , an apparatus for measuring choice reaction time


VPR model


An  encyclopedia  is a repository of general knowledge.


Questions drawn from the game  Trivial Pursuit  have been used in a number of psychological experiments concerning general knowledge. [ 17 ] [ 18 ]


Lewis Terman, founder of the Genetic Studies of Genius


Srinivasa Ramanujan , a  mathematician  who is widely regarded as a genius. He made substantial contributions to mathematics despite little formal training. [ 6 ]


Confucius , one of the most influential thinkers of the  ancient world [ 7 ] [ 8 ] [ 9 ] [ 10 ] [ 11 ] [ 12 ]  and the most famous  Chinese philosopher , [ 13 ]  is often considered a genius. [ 14 ] [ 15 ] [ 16 ] [ 17 ] [ 18 ]


Miguel de Cervantes , novelist who is acknowledged as a  literary  genius


Stanley Kubrick , deemed a  filmmaking  genius


Marie Curie ,  physicist  and  chemist  cited as a genius


Albert Einstein ,  theoretical physicist  who is considered a genius


Ibn al-Haytham , a scientist and polymath who is considered a genius [ 40 ]


Leonardo da Vinci  is widely acknowledged as having been a genius and a  polymath .


Wolfgang Amadeus Mozart , considered a  prodigy  and  musical  genius


The  Google Books Ngram Viewer  indicating a marked decline in use of the word "genius" from 1700 to 2022


The intellect comprises the  rational  and the  logical  aspects of the human mind.


The Structure of Intellect (SI) model organizes intellectual functions in three dimensions: (i) Operations, (ii) Contents, and (iii) Products. (Joy Paul Guilford, 1955)


Socrates  (c. 470 – 399 BC)


Psychologist  Alfred Binet , co-developer of the  Stanford–Binet test


Psychologist  Raymond Cattell  defined  fluid and crystallized intelligence  and authored the  Cattell Culture Fair III  IQ test.


Normalized IQ distribution with mean 100 and standard deviation 15


Physicist  Stephen Hawking . When asked his IQ, he replied: "I have no idea. People who boast about their IQ are losers." [ 218 ]


Google Search  traffic for the terms  aptiquant ,  browser iq  and  internet explorer iq  between July 28 and August 4


The  owl of Athena , a symbol of knowledge in the Western world


The definition of knowledge as justified true belief is often discussed in the academic literature.


The Gettier problem is grounded in the idea that some justified true beliefs do not amount to knowledge.


Declarative knowledge can be stored in books.


Knowing how to ride a bicycle is one form of non-propositional knowledge.


Perception relies on the  senses  to acquire knowledge.


Knowledge by testimony relies on statements given by other people, like the testimony given at a trial.


Pyrrho  was one of the first philosophical skeptics.


Foundationalism, coherentism, and infinitism are theories of the structure of knowledge. The black arrows symbolize how one belief supports another belief.


Los portadores de la antorcha (The Torch-Bearers)  – sculpture by  Anna Hyatt Huntington  symbolizing the transmission of knowledge from one generation to the next ( Ciudad Universitaria, Madrid, Spain )


The value of knowledge plays a key role in education for deciding which knowledge to pass on to the students.


The invention of the printing press in the 15th century greatly expanded access to written materials.


Saraswati  is the goddess of knowledge and the arts in Hinduism.


American students learning how to make and roll  sushi


Children learn to bike in the eighties in Czechoslovakia.


A depiction of the world's oldest continually operating university, the  University of Bologna , Italy


Future school  (1901 or 1910)


Learning Pyramid or Cone of Learning


Need for Cognition is associated with deep thought


This diagram shows the medieval understanding of  spheres  of the  cosmos , derived from  Aristotle , and as per the standard explanation by  Ptolemy . It came to be understood that at least the outermost sphere (marked " Primũ Mobile ") has its own intellect, intelligence or  nous  – a cosmic equivalent to the human mind.


The earliest surviving text that uses the word  nous  is the  Iliad .  Agamemnon  says to  Achilles : "Do not thus, mighty though you are, godlike Achilles, seek to deceive me with your wit ( nous ); for you will not get by me nor persuade me." [ 7 ]


Anaxagoras


The  Scholar and His Books  by  Gerbrand van den Eeckhout


Girl scouts  compete in the USS California Science Experience at Naval Surface Warfare Center Corona Division.


Examples of figures from  mental rotation  tests


A man playing a video game at the Japan Media Arts Festival. Spatial abilities can be affected by experiences such as playing action video games, complicating research on sex differences in spatial abilities.


Artificial intelligence, especially  foundation models , has made rapid progress, surpassing human capabilities in various  benchmarks .


Carroll's three-stratum model. Key:  fluid intelligence  (Gf), crystallized intelligence (Gc), general memory and learning (Gy), broad visual perception (Gv), broad auditory perception (Gu), broad retrieval ability (Gr), broad cognitive speediness (Gs), and processing speed (Gt). Carroll regarded the broad abilities as different "flavors" of  g .


Schematic illustrating one trial of each stimulus pool in the Sternberg task: letter, word, object, spatial, grating


People high in typical intellectual engagement particularly enjoy deep thought.


Two distribution curves with identical means but different variabilities. The curve with the greater variability (green) yields higher values in both the lowest and highest ends of the range.


Verbal perceptual model


Echolocation  in bats is one model system in neuroethology.


A depiction of the ultrasound signals emitted by a bat, and the echo from a nearby object


Spectrogram  of  Pipistrellus pipistrellus  bat vocalizations during prey approach. The recording covers a total of 1.1 seconds; lower main frequency c. 45 kHz (as typical for a common pipistrelle). About 150 milliseconds before final contact time between and duration of calls are becoming much shorter ("feeding buzz"). Corresponding audio file:


Auditory cortex of a bat  A  FM-FM area    B  CF-CF area    C  Amplitude-sensitive area    D  Frequency-sensitive area    E  DSCF area


Diagram illustrating sound generation, propagation and reception in a toothed whale. Outgoing sounds are cyan and incoming ones are green.


A Palawan swiftlet ( Aerodramus palawanensis ) flies in complete darkness inside the Puerto Princesa subterranean river cave.


The especially long tails on the hindwings of the  African moon moth , a  Saturniid , oscillate in flight, deflecting the hunting bat's attack to the tails and thus enabling the moth to evade capture. [ 94 ]


Wing feathers of a male  club-winged manakin , with the modifications noted by P. L. Sclater in 1860 [ 4 ]  and discussed by Charles Darwin in 1871. [ 5 ]  The bird produces sound with its wings.


The Western  Australian raven  ( Corvus coronoides , ssp.  perplexus ) makes a slow, high-pitched  ah-ah-aaaah  sound. [ 15 ]   Australian raven territorial call ⓘ


A mated pair of  white-naped cranes  ( Antigone vipio ) performing a "unison call", which strengthens the  pair bond  and provides a territorial warning to other cranes


Song-learning pathway in birds [ 68 ]


A timeline for song learning in different species. Diagram adapted from Brainard & Doupe, 2002. [ 88 ]


Song selectivity in HVCx neurons:  neuron activity in response to calls heard (green) and calls produced (red).  a.  Neurons fire when the primary song type is either heard or sung.  b, c.  Neurons do not fire in response to the other song type, regardless of whether it is heard or sung. [ 105 ]


The sonograms of  Luscinia luscinia  and  Luscinia megarhynchos  singing help to distinguish these two species by voice definitely.


Sonogram of the call of a  laughing dove .  Recorded in south India ⓘ


Animated representation of lobstering.


The tail-flip escape behavior was first described in the crayfish  Procambarus clarkii


The moth  Bertholdia trigona  is one of several moth species known to jam the echolocation of its predator


Among the electric fishes are  electric eels ,  knifefish  capable of generating an  electric field , both at low voltage for  electrolocation  and at high voltage to stun their  prey .


The  elephantnose fish  is a weakly electric fish which generates an electric field with its electric organ, detects small variations in the field with its  electroreceptors , and processes the detected signals in the brain to locate nearby objects. [ 12 ]


Impedance matching  in strongly electric fishes. Since seawater conducts far better than freshwater, marine fish operate at much higher currents but lower voltages. [ 13 ]


Anatomy of a strongly electric freshwater fish: the electric eel's three  electric organs . The main organ is long, with a stack of many electrocytes in series to provide a high voltage, matching the high impedance of freshwater.


An  electric ray  (Torpediniformes) showing paired electric organs in the head, and electrocytes stacked vertically within it


When a  glass knifefish  encounters a neighbour with a closely similar frequency, one fish shifts its frequency upward and the other downward in the  jamming avoidance response .


Bufo bufo , the common toad, was used in Jörg-Peter Ewert's studies of toad form vision


Neurons of the optic tectum are integrated in a neural macro-network in which various forebrain structures are involved; see  Vision in toads .  The prey-selective responses of tectal T5.2 neurons probably result from postsynaptic inhibitory input of pretectal thalamic neurons (cf. lines with terminal dots). Furthermore, there is ample evidence suggesting that retino-tectal glutaminergic transfer is controlled by neuropeptide Y (NPY) — released from the axonal terminals of pretectal thalamic TH3 neurons — in a manner of presynaptic inhibition via Y2 receptors.  Pretectal influences mediated by NPY are phylogenetically conserved properties in tetrapod vertebrates. (Combined after Ewert 1974 and 2004)


Eigenmannia virescens  is a weakly electric fish which produces continuous electric discharges.


Two neighboring  Eigenmannia  perform the jamming avoidance response: When two fish with around the same  frequency  meet, one fish shifts its frequency upward and the other shifts its frequency downward.


The  African knifefish  also has a jamming avoidance response,  evolved convergently .


Eigenmannia  sensory coding for jamming avoidance response. The fish avoids interference with its electrolocation signal by changing its frequency when a jamming signal is detected. This is mediated by a T-unit  tuberous receptor  which fires at the signal frequency, and a P-unit tuberous receptor which fires fastest near the peak of the  beat cycle  caused by the interference of two signals with similar frequencies.


A knollenorgan drawn by the German anatomist Viktor Franz, 1921. RC=receptor cell; b.m.= basal membrane; n=nerve. Line at top=skin surface. [ 1 ] The organ is embedded in the skin of  mormyrid  fishes, which actively  electrolocate  by generating brief electrical pulses with their  electric organ . The returns from the pulses, distorted by any nearby objects such as prey, are detected by the knollenorgans distributed around the fish's body.


Thermus aquaticus


Tyto alba , the Barn Owl


Ephaptic inhibition at the mauthner axon cap by PHP cells


Neural oscillatory output


Human brain regions


Spinal cord segment


Basic Neuron


Basic feedback loop


Different types of religious symbols


U.S. Capitol  – oil painting by  Allyn Cox  – The Monroe Doctrine (1823), plus a quote from President  Franklin D. Roosevelt  (1940).


A mother taking care of her child by feeding them.


Kimberlé Crenshaw  introducing her concept of  intersectionality  at one of her lectures


Honey bee ( Apis mellifera )


The round dance uses the position of the sun to indicate the direction from the hive to the food source in the same way that the  waggle dance  does.


The sexual dimorphism in Bibionidae eyes is prominent, with the large dorsal eyes of the male (left) entirely absent in the female (right)


Duplex theory


HRTF


HRIR


Sound localization with manikin


Eurasian eagle-owl in  Poland


Parallel processing pathways in the brain for time and level for sound localization in the owl


Most research on the detection of surface waves has been done on the  striped panchax ,  Aplocheilus lineatus


Capillary wave ripples on Lifjord in  Øksnes Municipality , Norway


A male shows the typical hunting stance of the fishing spider,  Dolomedes minor


The  waggle dance  - the direction the bee moves in relation to the hive indicates direction; if it moves vertically  the direction to the source is directly towards the Sun. The duration of the waggle part of the dance signifies the distance.


Figure-eight-shaped waggle dance of the honeybee ( Apis mellifera ). A waggle run oriented 45° to the right of ‘up’ on the vertical comb (A) indicates a food source 45° to the right of the direction of the sun outside the hive (B). The abdomen of the dancer appears blurred because of the rapid motion from side to side.


Workers of  Apis mellifera carnica  on honeycomb


Günther K.H. Zupanc


Günther Zupanc with German minister  Svenja Schulze  in Berlin in 2015


Günther K.H. Zupanc (left) and  Olaf Scholz  (right), Chancellor of the Federal Republic of Germany, in the city hall of Bremen in 2024


Neural stem cell (radial glia) shown in green


Schematic of the brain areas that are part of the songbird song system


Schematic of avian hippocampus formation, containing the ventral dorsomedial region (DMv), the dorsal dorsomedial region (DMs), the triangular region (Tr) and the V-shaped region, divided into lateral (Vl) and medial (Vm).(Adapted from Barnea et al., 2012) [ 2 ]


Structure of VEGFA trophic factor.


Figure 4: Male zebra finch ( Taeniopygia guttata),  an example of a sensitive period learner


Schematic of seasonal fluctuations of testosterone levels in the HVC and how they modulates survival of newborn RA projecting HVC neurons.(Adapted from Brenowitz and Larson, 2015 [ 10 ] )


Male canary ( Serinus canaria) ,  an example of an open-ended learner


Example of BrdU staining (in green) of radial glia cells expressing doublecortin (DCX - in blue)


Structure of the DCX protein


Aplysia egg mass


An  Aplysia fasciata  (above) and a couple of  Aplysia punctata  (below) grazing in a tide pool in  Póvoa de Varzim ,  Portugal .


Movement of wild-type


Lateral (left) side of an adult-stage hermaphrodite


Tissues of an adult  C.   elegans


Size and morphology of different  C.   elegans  cells


Anatomical diagram of a male  C. elegans


C. elegans  under a microscope


Once he recognizes a hermaphrodite worm, the male nematode begins tracing the hermaphrodite with his tail until he reaches the vulval region. The male then probes the region with his spicules to locate the vulva, inserts them, and releases sperm. [ 27 ]


C. elegans  embryonic development


Anatomy and scale of  C. elegans  developmental stages


Life cycle and developmental stages of  C. elegans


Wild-type  C. elegans  hermaphrodite stained with the fluorescent dye  Texas Red  to highlight the nuclei of all cells


C. elegans  hermaphrodite


C. elegans  adult with GFP coding sequence inserted into a histone-encoding gene by  Cas9 -triggered homologous recombination


Droppings from a  Manduca sexta  larva


Stages of zebrafish development. Photos to scale except adult, which is about 2.5 cm (1 in) long.


A leopard danio


Zebrafish  chromatophores , shown here mediating  background adaptation , are widely studied by scientists.


A zebrafish pigment mutant (bottom) produced by insertional  mutagenesis . [ 10 ]  A wild-type embryo (top) is shown for comparison. The mutant lacks black  pigment  in its  melanocytes  because it is unable to synthesize  melanin  properly.


FDA research used Zebrafish to show the effects of  ketamine  on neurological development.


The development of a single zebrafish retina captured on a light sheet microscope approx. every 12 hours from 1.5 days to 3.5 days after birth of the embryo


The classic Identity theory and anomalous monism in contrast. For the Identity theory, every  token  instantiation of a single mental type corresponds (as indicated by the arrows) to a physical token of a single physical type. Hence there is type-identity. For anomalous monism, the token-token correspondences can fall outside of the type-type correspondences. The result is token identity.


The classical Cartesian model of the mind under which body,  world, perception and action are understood as independent


The embodied cognitive model of the mind under which body, world, perception and action are dynamically related with each other


A timeline graph reconstructing historically relevant developments and key contributions that influenced the growth of embodied cognition. To the left are the years in descending order. The legend on the top-right corner indicates how to interpret the connections made.


The scope of embodied cognition and the intertwined relationship that arise between the sciences


The applications of embodied cognition and artificial intelligence


Example of the " change blindness " illusion. These two alternating images contain several differences that most people struggle to find right away. It emphasizes the fact that perception is active and demands attention.


Demonstration of dynamic depictive gestures for the Triangle conjecture


Response times for the positive, negative, and neutral valence conditions in the approach and avoidance experiment. Participants were significantly faster for the "positive toward" condition regardless of the central word's valence.


The approach and avoidance task. The top image depicts the zooming-out effect for avoidance and the bottom image the zooming-in effect for approach (as indicated by the arrows on the computer screen). The smaller images exemplify the approach and avoidance task performed by participants when using either the response pad or the joystick.


Results from a social embodied cognition study that illustrate the relationship between positive emotions, observed behavioral synchrony, and embodied rapport [ 149 ]


Visual Perspective Taking.  VDP1 : From his perspective, the ball is not visible.  VDP2:  The woodpile is on the left of the tree. [ 152 ]


The Mathematics Imagery Trainer for Proportion. A tool to help students learn proportion.


An Atlas robot connecting a hose to a pipe in a  Gazebo   computer simulation


An Atlas robot climbing into a vehicle. The image was recreated in a Gazebo computer simulation.


The experience of  the phantom limb illusion , which occurs after a limb has been amputated


Chalmers on stage for an  Alan Turing Year  event at  De La Salle University , Manila, 27 March 2012


The hard problem is often illustrated by appealing to the logical possibility of inverted visible spectra. If there is no logical contradiction in supposing that one's colour vision could be inverted, it follows that mechanistic explanations of visual processing do not determine facts about what it is like to see colours.


A diagram showing the relationship between various views concerning the relationship between consciousness and the physical world


Structure of a typical  neuron  with  Schwann cells  in the  peripheral nervous system


Diagram showing the major divisions of the vertebrate nervous system


Horizontal section of the head of an adult female human, showing skin, skull, and brain with  gray matter  (brown in this image) and underlying  white matter


Nervous system of a bilaterian animal, in the form of a nerve cord with segmental enlargements, and a "brain" at the front


Area of the human body surface innervated by each spinal nerve


Earthworm nervous system.  Top:  side view of the front of the worm.  Bottom:  nervous system in isolation, viewed from above


Internal anatomy of a spider, showing the nervous system in blue


Simplified diagram of the mollusc nervous system


Major elements in synaptic transmission. An electrochemical wave called an  action potential  travels along the  axon  of a  neuron . When the wave reaches a  synapse , it provokes release of a small amount of  neurotransmitter  molecules, which bind to chemical receptor molecules in the membrane of the target cell.


Illustration of pain pathway, from  René Descartes 's  Treatise of Man


Simplified schema of basic nervous system function: signals are picked up by sensory receptors and sent to the spinal cord and brain, where processing occurs that results in signals sent back to the spinal cord and then out to motor neurons


Human embryo, showing neural groove


Four stages in the development of the neural tube in the human embryo


Layers protecting the brain and spinal cord


Axial section of the Brainstem (Pons) at the level of the Facial Colliculus


The Clivus


Limitation of  abduction  of the right eye. This individual tries to look to his right, but the right eye fails to turn to the side.


The accessory nerve supplies the  sternocleidomastoid  and  trapezius muscles


Right chorda tympani nerve, viewed from lateral side


Binocular geometry. The absolute disparity is the angle between visual lines that intersect at a given point. The relative disparity is the difference between the absolute disparity of 2 points. The Vieth–Müller circle, or horizontal geometrical horopter, is the set of points that have 0-relative disparity to fixation (thus the same absolute disparity as fixation). Geometrically this is a circle passing through the nodal point of the 2 eyes and through fixation. The empirical horopter, measured according to a given criterion such as identical visual directions in the 2 eyes, does not fall on the geometrical horopter. It is concave as short fixation distances, flat at the abathic distance and then convex.


Schematic image of the hypoglossal nerve and innervation targets.


An injured hypoglossal nerve will cause the tongue to  waste away  and the tongue will not be able to stick out straight. The injury here occurred because of  branchial cyst  surgery.  [ 18 ]


Motor nerves wrapped in endoneurium


Neural stem cells seen in green


Normal Brain Development (left), Microcephaly, a type of encephalopathy (right)


Human embryonic stem colonies (A), axonal outgrowths (B)


Mouse Embryonic Stem Cells (mESCs) embryoid bodies (EBs)


Neuroanatomy is the study of the  anatomy  and organisation of the nervous system. Pictured here is a cross-section showing the  gross anatomy  of the  human brain .


J. M. Bourgery 's anatomy of the brain, brainstem, and upper spinal column


Para-sagittal  MRI  of the head in a patient with benign familial  macrocephaly


Nervous system of a generic bilaterian animal, in the form of a nerve cord with segmental enlargements, and a "brain" at the front


A  fundus photograph  showing the back of the retina. The white circle is the beginning of the optic nerve.


The  visual system  and the  somatosensory system  are active even during  resting state fMRI


Activation and response in the sensory nervous system


The  human eye  is the first element of a  sensory system : in this case,  vision , for the  visual system .


Human  ear


Human nose


Human  tongue


Disability-adjusted life year  for sense organ diseases per 100,000 inhabitants in 2002. [ 29 ]      no data      less than 200      200-400      400-600      600-800      800-1000      1000-1200      1200-1400      1400-1600      1600-1800      1800-2000      2000-2300      more than 2300


This figure depicts an example of combination of a forward model and an inverse model. Here the reference input is the target sensory state that controller (inverse model) will use to compute a motor command. The plant ( motor unit ) acts out the motor command which results in a new sensory state. This new sensory state can be compared to the state predicted by the forward model to  obtain an error signal. This error signal can be used to correct the internal model or the current movement.


Dermatome  distribution of the trigeminal nerve


Dermatome distribution of the trigeminal nerve


C = Cervical segment, S = Sacral segment, VPL =  Ventral posterolateral nucleus , SI =  Primary somatosensory cortex , VM =  Ventromedial prefrontal cortex , MD =  Medial dorsal thalamic nucleus , IL =  Intralaminar nucleus , VPM =  Ventral posteromedial nucleus , Main V =  Main trigeminal nucleus , Spinal V =  Spinal trigeminal nucleus


Brainstem nuclei: Red = Motor; Blue = Sensory; Dark blue = Trigeminal nucleus


Onion-skin distribution of the trigeminal nerve


Cortical homunculus


The Cavernous Sinus


Vagus nerve


H&E stained  fibers of the vagus nerve (bottom right) innervate the  sinoatrial node  tissue (middle left)


Human vestibular system of the  semicircular canals  in the inner ear


Cochlea and vestibular system


Push-pull system of the semicircular canals, for a horizontal head movement to the right.


The vestibulo-ocular reflex. A rotation of the head is detected, which triggers an inhibitory signal to the  extraocular muscles  on one side and an excitatory signal to the muscles on the other side. The result is a compensatory movement of the eyes.


Neural pathway  of the vestibular system


Visual cycle


Representation of molecular steps in photoactivation (modified from Leskov et al., 2000 [ 4 ] ). Depicted is an outer membrane disk in a rod.  Step 1 : Incident photon (hν) is absorbed and activates a  rhodopsin  (likewise  photopsin ) by conformational change in the disk membrane to R*.  Step 2 : Next, R* makes repeated contacts with transducin molecules, catalyzing its activation to G* by the release of bound GDP in exchange for cytoplasmic GTP, which expels its β and γ subunits.  Step 3 : G* binds inhibitory γ subunits of the phosphodiesterase (PDE) activating its α and β subunits.  Step 4 : Activated PDE hydrolyzes cGMP.  Step 5 : Guanylyl cyclase (GC) synthesizes cGMP, the second messenger in the phototransduction cascade. Reduced levels of cytosolic cGMP cause cyclic nucleotide gated channels to close preventing further influx of Na +  and Ca 2+ .


The absorption of light leads to an isomeric change in the retinal molecule.


3D reconstruction of five cortical columns in rat vibrissal cortex


Default mode network connectivity. This image shows main regions of the default mode network (yellow) and connectivity between the regions color-coded by structural traversing direction (xyz → rgb). [ 1 ] [ 2 ]


Graphs of the dynamic development of correlations between brain networks. (A) In children the regions are largely local and are organized by their physical location; the frontal regions are highlighted in light blue. (B) In adults the networks become highly correlated despite their physical distance; the default network is highlighted in light red. [ 24 ]  This result is now believed to have been confounded by artifactual processes attributable to the tendency of younger subjects to move more during image acquisition, which preferentially inflates estimates of connectivity between physically proximal regions (Power 2012, Satterthwaite 2012).


Simplified diagram of frontal cortex to striatum to thalamus pathways.


3D Vizualization of the Galves–Löcherbach model simulating the spiking of 4000 neurons (4 layers with one population of inhibitory neurons and one population of excitatory neurons each) in 180 time intervals.


Illustration of the general Galves-Löcherbach model for a neuronal network of 7 neurons, with indices

 I
 =
 {
 1
 ,
 2
 ,
 …
 ,
 7
 }

 {\displaystyle I=\{1,2,\ldots ,7\}}

 . The matrix of 0s and 1s represents the firing history

 X
 [
 −
 ∞

 :

 t
 ]

 {\displaystyle X[-\infty \,{\mathrel {:}}\,t]}

  up to some time

 t

 {\displaystyle t}

 , where row

 i

 {\displaystyle i}

  shows the firings of neuron

 i

 {\displaystyle i}

 .  The rightmost column shows

 X

 i

 [
 t
 −
 1
 ]

 {\displaystyle X_{i}[t-1]}

 . The blue digit indicates the last firing of neuron 3 before time

 t

 {\displaystyle t}

 , which occurred in the time step between

 τ

 3

 [
 t
 ]

 {\displaystyle \tau _{3}[t]}

  and

 τ

 3

 [
 t
 ]
 +
 1

 {\displaystyle \tau _{3}[t]+1}

 . The blue frame encloses all firing events that influence the probability of neuron 3 firing in the step from

 t

 {\displaystyle t}

  to

 t
 +
 1

 {\displaystyle t+1}

  (blue arrow and empty blue box).  The red details indicate the corresponding concepts for neuron 6.


Figure 1. Neuron anatomy for network model


Figure 2 Types of brain connectivity


Figure 4(a)Basic telecommunication network


Figure 4(b)Basic MLP technology model  Figure 4. Telecommunication network and neural network topologies


Figure 5 Membrane model


Figure 6 Neuron model


Plot of typical position coding


Neural responses are noisy and unreliable.


A neural pathway connects one part of the  nervous system  to another using bundles of  axons  called tracts. The  optic tract  that extends from the  optic nerve  is an example of a neural pathway because it connects the eye to the brain; additional pathways within the brain connect to the  visual cortex .


Neural pathways of  cerebellar cortex


Pathways in the  ciliary ganglion . Green=Parasympathetic; Red=Sympathetic; Blue=Sensory


Diagram showing cortical pathways


Characteristic spiking behavior of neuron


Neural synapse


A retinal amacrine cell


Effect of noise on non-spiking neuron transmission


Plasticity in the brain affects the strength of neural connections and pathways.


The neuronal soma, axon, and dendrites are involved in nonsynaptic plasticity and affect the plasticity at the synapse


Neurons interact in complex networks that affect the generation of action potentials in other neurons.


Action potential propagation animation


Schematic of phase precession in three  place cells . A rat runs left-to-right and the firing of the cells (shown as colored tick marks) is spatially localized, with the three place fields (represented by the three colors) overlapping. The  local field potential   theta rhythm  is shown at the bottom in black. The  action potentials  of each cell occur earlier and earlier with respect to the theta peak on each successive cycle – this is phase precession. One consequence of this is that within a single theta cycle (blue-shaded rectangle, for example) the cells fire in the same sequence in time as their triggering is organized in space: thus converting a spatial code into a temporal one.


The  phase  of ongoing oscillatory activity is reset.


Neuron in the hippocampus of an epileptic patient


A fictional EEG showing a sleep spindle and  K-complex  in stage 2 sleep.


Synaptic plasticity rule for gradient estimation by dynamic perturbation of conductances


Thiamine pyrophosphate  structure. As a result of nutritional deficiency in those with alcoholic polyneuropathy, low thiamine levels are usually present and have been proposed as a cause of the nerve destruction.


An  intravenous  home  parenteral nutrition  formula may be a part of the treatment plan for those with alcoholic polyneuropathy who also have a nutritional deficiency.


Total recorded alcohol consumption per capita of individuals 15 years or older, in liters of pure alcohol. Alcoholism is the main cause of alcoholic polyneuropathy.


Conversion of  ethanol  to  acetaldehyde . The toxic buildup of acetaldehyde may result in alcoholic polyneuropathy.


John C. Lettsome  noted in 1787  hyperesthesia  and  paralysis  in legs more than arms of patients, a characteristic of alcoholic polyneuropathy.


Chromosome 17


Denervation   atrophy  of type II  muscle fibers


Ankle-foot orthosis


This magnified image of type 2 muscle fibers shows denervation atrophy occurring at the white spaces at the top left and bottom center of the image. The white space represents a disruption of the nerve fibers, resulting in a loss of nerve supply to the muscle fibers.


Illustration depicting areas affected by diabetic neuropathy


Vincristine


Valsalva maneuver


The H 2  receptor antagonist cimetidine


Erythromelalgia in hands of a Scandinavian male, 52, after holding a book).


EM episode in a foot triggered by dipping it in warm water. The EM in this case is caused by an underlaying small fiber neuropathy.


Toes during an EM flareup


Silas Weir Mitchell


Sir Thomas Barlow


The  facial nerve


No Tears: Life With FD, a comic strip created by Mindy Indy, portrays the lives of kids and teenagers living with Familial Dysautonomia.


Autosomal recessive  inheritance


Various patterns of manifestation of Guillain–Barré syndrome


A  scanning electron microscope -derived image of  Campylobacter jejuni , which triggers about 30% of cases of Guillain–Barré syndrome


Guillain–Barré syndrome – nerve damage


Georges Guillain , together with Barré and Strohl, described two cases of self-limiting acute paralysis with peculiar changes in the cerebrospinal fluid. He succeeded his teacher  Pierre Marie  as professor of neurology at the  Salpêtrière  hospital in Paris in 1925. [ 58 ]


Autosomal dominant mode of inheritance


Scheme showing sympathetic and parasympathetic innervation of the pupil and sites of a lesion in Horner's syndrome.


Left-sided Horner's syndrome in a cat as a result of trauma, demonstrating miosis in left pupil.


Illustration of imaging from a CT-guided nerve block. The needle tip has been placed at the top of the pudendal canal to block the pudendal nerve.


Nerve compression in neurapraxia


Several signaling pathways are upregulated following a nerve injury.


This tackle which occurred during an Army versus Navy game is representative of those that occur in  American football .  Neurapraxia is a common injury in all levels of football.


Tetrahydrocannabinol


Histological comparison of a normal nerve and an atrophied nerve using a cross-slice of the sciatic nerve. Left is a normal nerve. Right is an atrophied nerve.


Anatomy of a myelinated nerve cell


Anatomy of a nerve fiber


Carpal tunnel syndrome is caused by compression of the median nerve at the carpal tunnel. The carpal tunnel is formed by the bones of the wrist and the transverse carpal ligament.


Fibrovascular bands are dense bands of scar tissue with a vascular supply that can restrict mobility of the sciatic nerve. Top left is a compressive / bridge-type band, like a seat belt. Top right is an adhesive / horse-strap band, like a leash. Bottom center is undefined distribution that restricts mobility in multiple directions, like a splattering of glue.


Hip adduction is a strengthening exercise for the piriformis muscle. A cable attached at the ankle can be used to adduct the hip, bringing the leg in toward the opposite side of the body. The same equipment can also be used for hip abduction, where the leg starts beside the opposing leg and moves out to the side, away from the body. [ 49 ] [ unreliable medical source? ]


Ultrasound scan (left) and ultrasound-guided injection (right) of the piriformis muscle. Gmax = gluteus maximus; Pm = piriformis muscle; sn = sciatic nerve; S = sacrum; H = hip bone.


Action potential  propagation in myelinated neurons is faster than in unmyelinated neurons(left)


Human T Cell


Micrograph of a muscle biopsy


Methylprednisolone


Person standing and measuring heart rate with a  pulse oximeter  which shows tachycardia of 108 bpm


Results of a tilt table test positive for POTS


Anatomy of the pudendal nerve from the spinal nerve roots to the terminal branches in an adult male.


CT-guided block injection of the pudendal nerve at the pudendal canal.


Humerus - anterior view


Hand tendons


Brachial plexus . C6 and C7 nerves affected most frequently.


Oblique  projectional radiograph  of a man presenting with pain by the  nape  and left shoulder, showing a stenosis of the left  intervertebral foramen  of  cervical spinal nerve 4 , corresponding with the affected  dermatome .


CT scan  of a man presenting with radiculopathy of the left  cervical spinal nerve 7 , corresponding to  spondylosis  with osteophytes between the vertebral bodies C6 and C7 on the left side, causing foraminal stenosis at this level (lower arrow, showing  axial plane ). There is also spondylosis of the  facet joint  between C2 and C3, with some foraminal stenosis at this level (upper arrow), which appears to be asymptomatic.


Cervical traction machine


Sciatica often results in pain radiating down the leg.


Left: Illustration of herniated spinal disc, superior view. Right: MRI showing herniated L5-S1 disc (red arrow tip), sagittal view.


Illustration of fibrovascular bands restricting mobility of the sciatic nerve in multiple directions, like a splattering of glue


Straight leg  test sometimes used to help diagnose a lumbar herniated disc


Thoracic outlet syndrome


Olecranon


Nerve conduction study  (Calculation of  (NCV)


winging of the right scapula


Winging of the left scapula


Scapula-to-scapula scapulopexy, pre- and post-operation in person with FSHD. The scapulas are tethered together into a retracted position with an  Achilles tendon  graft. In the right image, the rhomboid major muscles are distinguishable.


Autonomic nervous system, showing  splanchnic nerves  in middle, and the vagus nerve as "X" in blue. The heart and organs below in list to right are regarded as viscera.


Function of the autonomic nervous system [ 16 ]


A flow diagram showing the process of stimulation of adrenal medulla that makes it release adrenaline, that further acts on adrenoreceptors, indirectly mediating or mimicking sympathetic activity


benign prostatic hyperplasia


Manifestation of Raynaud phenomenon


Myocardial infarction (heart attack)


Demonstration of orthostatic hypotension


heart failure


Demonstration of thickening of airway


Damaged alveoli of a chronic obstructive pulmonary disease patient


Overview of Parasympathetic Nervous System


Ibuprofen  as an NSAID, can cause drug interaction with beta-1 blocker


Mechanism of Action of Alpha -1 blocker


Mechanism of Action of Alpha-2 blocker


Chemical structure of  bethanechol


Chemical structure of  physostigmine


Chemical structure of  atropine


Chemical structure of  terbutaline


Chemical structure of  atenolol


Flowchart showing baroreceptor reflex


Baroreflex activation is distinct from vagal stimulation. It works through an afferent limb which has the double effect of stimulating vagal outflow and attenuating global sympathetic outflow.


Piloerection (goose bumps), the physical part of frisson


A  CT scan  showing evidence of the nasal cycle: the more patent airway is on the right of the image, the swollen turbinates congesting the left


A) Pneumo-optical Probe,  B)  Pneumatic Probe.


Acetylcholine


Norepinephrine


Heart rate (HR) (first row), tidal volume (Vt) (second row), Vt and superimposed HR (third row). The HR modulation is clearly visible: HR increases with inspiration and decreases with expiration.


Heart rate (HR) (first row), ECG signal (ECG) (second row), and respiration (third row) for a newborn subject in a 15-seconds recording. HR expresses oscillations synchronous with respect to respiration.


RSA magnitude estimation based on a multivariate approach based on joint analysis of ECG and respiration. [ 15 ]  The green line shows the heart rate variations averaged over several breathing cycles. This clearly shows the trends that are typical of RSA.


Vagus nerve


H&E stained  fibers of the vagus nerve (bottom right) innervate the  sinoatrial node  tissue (middle left)


Figure 2.  Example of bifurcating axons in the  optic chiasm  (Type II) of a rabbit. a,b,c: bifurcating optic fibres. c: fibre bifurcating in the two opposite optic tracts. d. Commissure of Gudden. e. Fibres that continue in a different depth. (from: Cajal, [ 5 ]  Fig. 6)


Figure 3.  The decussation of the optic radiation in the cortex is an example of a type IV crossing


Nerve cell and organization


Cross-section of a nerve


Micrograph  demonstrating  perineural invasion  of  prostate cancer .  H&E stain .


Photo of Mathieu Jaboulay courtesy of Romain Rochefeuille


Magnetic Resonance Image of Lumbar Spine courtesy of Nevit Dilmen


Nerve block of cervical spine courtesy of PainDoctorUSA


Peripheral nervous system box diagram


Langley's Classification Tree from his 1921 book  The Autonomic Nervous System


Myelinated   GS efferent fiber  leaving cell body of motor neuron to form a neuromuscular junction


Spinal nerve


Cervical plexus


Anatomical illustration of the  brachial plexus  with areas of roots, trunks, divisions and cords marked. Clicking on names of branches will link to their Wikipedia entry.


The  lumbar plexus  and its branches.


Plan of sacral and coccygeal plexuses.


Distribution of the areas of the sensory roots upon the surface of the body


3D Medical Animation still shot of Lumbosacral Plexus


Typical spinal nerve location


Scheme showing structure of a typical spinal nerve 1.  Somatic efferent . 2.  Somatic afferent . 3,4,5.  Sympathetic efferent . 6,7.  Autonomic afferent .


Cervical nerves


Lumbar plexus and branches


Plan of sacral and pudendal plexuses


Areas of distribution of the cutaneous branches of the posterior divisions of the spinal nerves. The areas of the medial branches are in black, those of the lateral in red


This shows a simulated example of motorcyclist colliding with the floor at an angle, which may damage the brachial plexus nerves. The photo shows how head and shoulder are extremely separated, which may stretch or even tear the nerves in the between area. Protective gear can help prevent nerve damage by providing extra support on the opposite side of the head to prevent over-stretching the neck.


Brachial Plexus relation with the clavicle and the subclavian artery.


Approximate location of the celiac plexus on the  coronal plane


Lower half of right sympathetic cord


Scheme showing sympathetic and parasympathetic innervation of the pupil and sites of lesion in a Horner's syndrome.


Sacral plexus


The  corticospinal tract  is one of the major descending pathways from the  brain  to the α-MNs of the  spinal cord .


Alpha motor neurons are located in lamina IX according to the  Rexed lamina system .


Under the influence of the protein  sonic hedgehog , shown here, cells of the  floor plate  of the developing spinal cord differentiate into alpha motor neurons.


Poliomyelitis , caused by the  poliovirus  seen here, is associated with the selective loss of cells within the ventral horn of the  spinal cord , where α-MNs are located.


Typical recording of a Bereitschaftspotential


Gamma Motor Neurons are derived from the basal plate of the embryo


General depiction of a motor unit, consisting of a motor neuron innervating a group of muscle fibers.


Ion channel linked receptor Ions Ligand  (such as  acetylcholine )  When ligands bind to the receptor, the  ion channel  portion of the receptor opens, allowing ions to pass across the  cell membrane .


Botulinum toxin  injected in human face


Muscle types by fiber arrangement


Types of  pennate muscle . A –  unipennate ;  B –  bipennate ;  C –  multipennate


ATPase staining of a muscle cross section. Type II fibers are dark, due to the alkaline pH of the preparation. In this example, the size of the type II fibers is considerably less than the type I fibers due to denervation atrophy.


Structure of muscle fibre showing a sarcomere under  electron microscope  with schematic explanation.


Diagram of sarcoplasmic reticulum with terminal cisternae and  T-tubules .


Human embryo  showing  somites  labelled as  primitive segments .


Classes of levers present in the human skeletal muscular system


When a sarcomere contracts, the Z lines move closer together, and the I band becomes smaller. The A band stays the same width. At full contraction, the thin and thick filaments overlap.


Contraction in more detail


(a) Some ATP is stored in a resting muscle. As contraction starts, it is used up in seconds. More ATP is generated from creatine phosphate for about 15 seconds. (b) Each glucose molecule produces two ATP and two molecules of pyruvic acid, which can be used in aerobic respiration or converted to  lactic acid . If oxygen is not available, pyruvic acid is converted to lactic acid, which may contribute to  muscle fatigue . This occurs during strenuous exercise when high amounts of energy are needed but oxygen cannot be sufficiently delivered to muscle. (c) Aerobic respiration is the breakdown of glucose in the presence of oxygen (O2) to produce carbon dioxide, water, and ATP. Approximately 95 percent of the ATP required for resting or moderately active muscles is provided by aerobic respiration, which takes place in mitochondria.


Exercise-induced signaling pathways in skeletal muscle that determine specialized characteristics of slow- and fast-twitch muscle fibers


Jogging  is one form of aerobic exercise.


In  muscular dystrophy , the affected tissues become disorganized and the concentration of  dystrophin  (green) is greatly reduced.


Prisoner of war exhibiting muscle loss as a result of  malnutrition .


Skeletal muscle cell types include: very large multinuclear  muscle fiber cells ; small  endothelial cells  that line the inside of capillary blood vessels; small fibro-adipogenic progenitor cells (FAPs) which are muscle-fiber-adjacent multipotent mesenchymal stem cells that under different conditions can differentiate into adipocytes, fibroblasts or osteocytes.  Also shown are pericytes situated on the outer surface of blood capillaries where they interact with the underlying endothelial cells.  In addition,  satellite cells  are shown that can fuse with muscle fibers and contribute new myonuclei to muscle fibers, grow into  new myocytes , or support focal membrane damage repair. [ 98 ]


Regulation of transcription in mammals.   An active enhancer regulatory region is enabled to interact with the promoter region of its target gene by formation of a chromosome loop. This can allow initiation of messenger RNA (mRNA) synthesis by RNA polymerase II (RNAP II) bound to the promoter at the transcription start site of the gene. The loop is stabilized by one architectural protein anchored to the enhancer and one anchored to the promoter, and these proteins are joined together to form a dimer (red zigzags). Specific regulatory transcription factors bind to DNA sequence motifs on the enhancer. General transcription factors bind to the promoter. When a transcription factor is activated by a signal (here indicated as phosphorylation shown by a small red star on a transcription factor on the enhancer), the enhancer is activated and can now activate its target promoter. The active enhancer is transcribed on each strand of DNA in opposite directions by bound RNAP IIs. Mediator (a complex consisting of about 26 proteins in an interacting structure) communicates regulatory signals from the enhancer DNA-bound transcription factors to the promoter.


A  nucleosome  with  histone  tails set for transcriptional activation ....DNA in the nucleus generally consists of segments of 146  base pairs  of DNA wrapped around  nucleosomes  connected to adjacent nucleosomes by  linker DNA .  Nucleosomes consist of four pairs of histone proteins in a tightly assembled core region plus up to 30% of each histone remaining in a loosely organized  polypeptide  tail (only one tail of each pair is shown). The pairs of histones, H2A, H2B, H3 and H4, each have  lysines  (K) in their tails, some of which are subject to post-translational modifications consisting, usually, of acetylations [Ac] and methylations {me}. The lysines (K) are designated with a number showing their position as, for instance, (K4), indicating lysine as the 4th amino acid from the amino (N) end of the tail in the histone protein. The particular acetylations [Ac] and methylations {Me} shown are those that occur on nucleosomes close to, or at, some DNA regions undergoing transcriptional activation of the DNA wrapped around the nucleosome.


The  patellar reflex  is an example of the stretch reflex.


Part of the causal chain leading to  Alzheimer's disease


Deaths due to neurological conditions per million persons 2012     18-52    53-68    69-84    85-99    100-131    132-157    158-186    187-243    244-477    478-1,482


Some of the fields that contribute to understanding mental functioning


Table from the 2010  DrugScience  study ranking various drugs (legal and illegal) based on statements by drug-harm experts. This study rated alcohol the most harmful drug overall, and the only drug more  harmful to others  than to the users themselves. [ 4 ]


Acute confusional state caused by alcohol withdrawal, also known as  delirium tremens


Chromosome 15


Melatonin


"Boy with a Puppet" or "A child with a drawing", circa 1520, by  Giovanni Francesco Caroto ; the portrait motivated the initial naming of Angelman syndrome as  puppet syndrome . [ 45 ]


People with Asperger syndrome often display restricted or specialized interests, such as this boy's interest in stacking cans.


Functional magnetic resonance imaging  provides some evidence for mirror neuron theory. [ 79 ]


Students and families walk to support Autism Awareness Month.


The  trigeminal nerve .


The mythical Oedipus gouged his eyes out.


Different sections of semicircular canals.  utricle  and  saccule  are indicated by circles.


Basilar invagination in an infant with  Wolf–Hirschhorn syndrome .


Thyroid transcription factor associated with BHC


Motor cortex region involved in the learning retention


Left eye showing proptosis.


Visual field of homonymous hemianopia


Fluorescein angiography can reveal arteriovenous malformations.


A coup injury occurs under the site of impact with an object, and a contrecoup injury occurs on the side opposite the area that was hit.


Bromide rash


BVVL has autosomal recessive pattern of inheritance


Electroencephalogram (EEG) displaying burst suppression patterns. Onset of bursts are indicated by solid arrows; offset, by open arrows. In both A and B, the interval between each vertical dotted line is one second.


Patients with a high burst suppression ratio (yellow circles) show significantly better recovery from coma (traumatic etiologies) as measured by the Glasgow Outcome Scale extended (GOSe) 6 months post-injury (histogram on vertical axis). Figure from Frohlich et al. 2021 Frontiers in Neurology.


A clinical photograph showing a patient with the flexed posture. It can be abated when lying down. [ 1 ]


Alexandre-Achille Souques was one of the first major researchers of camptocormia and created the definition and name used for the condition to this day.


Spinal-muscle biopsy showing intense endomysial deposit of  fibrosis  (green) and fatty infiltration. Also observable is irregular distribution of involuted muscle fibers. (Trichrome, original magnification ×9100) [ 2 ]


Thymatron IV used for electroconvulsive therapy


Typical  deep brain stimulation  setup


Diplopia is a symptom that individuals with cerebellar degeneration may experience.


Diagram of two different nerve cells. The diagram on the left shows a nerve cell that is healthy and normally-functioning. The diagram on the right shows a nerve cell with a damaged myelin sheath, being the cause of multiple sclerosis.


Magnetic resonance imaging scans of two different brains. The scan of the brain on the left indicates a weakened, deteriorated cerebellum of a human with cerebellar degeneration. The scan of the brain on the right indicates a healthy, normally-functioning cerebellum of a human.


Coronal CT of the brain showing a choroidal fissure cyst


Structure of a typical neuron with  Schwann cells  in the  peripheral nervous system


Cockayne syndrome has an  autosomal recessive  pattern of  inheritance .


Johnny Head-in-Air is an absent-minded boy who seems unaware of his surroundings.


Animation of cortical spreading depression


Cortical spreading depression seen using intrinsic optical signal imaging in  gyrencephalic  brain. Speed 50x. [ 1 ]


Hemodynamic changes observed after  MCA  occlusion in IOS. The video has a speed of 50x to better appreciate the SDs through human eye. Pictures are dynamically subtracted to a reference picture 40 s before. First we see the initial area of change at the exact moment where the left MCAs are occluded. The area is highlighted with a white line. Later we appreciate the signal produced by SDs. [ 2 ]


Drawing by  Donald Ogden Stewart  published in 1921 showing Little Elmer's father with DTs and seeing pink elephants


Huyghe Brewery 's flagship beer is  Delirium Tremens , a golden ale.


Guillain–Barré syndrome – demyelination


Daniel Radcliffe, actor, has dyspraxia.


Weight loss from diencephalic syndrome


Punding , a possible symptom of DDS, is the repetition of complex motor behaviors such as collecting or arranging objects.


A slot machine, commonly used for gambling.


The dopamine transporter protein, pictured here, is mutated in DTDS patients.


Dysgraphia can be difficult to diagnose because the handwriting starts out clear and slowly degrades, making the writer appear lazy.


Figure 1.  Schematic structure of K V 1.1 with the episodic ataxia type 1 mutations noted in red.


Figure 2.  Schematic structure of Ca V 2.1 with the episodic ataxia type 2 mutations noted in red.


Kaiser   Wilhelm II  was affected by Erb's palsy in his left arm.


Some of the steps in the manufacture of felt hats are illustrated in this image from 1858.


A man working in hat manufacture with no protective equipment, putting him at risk for mercury poisoning


Picture postcard of a hat factory in Danbury (postmarked 1911)


While the name of Lewis Carroll's Mad Hatter may contain an  allusion  to the hatters' syndrome, the character itself appears to have been based on an eccentric furniture dealer.


Convulsive symptoms of ergotism


Claviceps purpurea  fungal  sclerotium  growing on barley


Ergot in  barley


Detail from the painting  Temptation of St Anthony  by  Matthias Grünewald , showing a patient with advanced ergotism


" Right hemisphere of the brain "


Figure from a paper by J. Driver and P. Vuilleumier explaining the effect of grouping on extinction reduction.


Facial characteristics of a child with FAS


A  label on alcoholic drinks  promoting zero alcohol during  pregnancy


Smooth philtrum seen on a six-month-old baby with FAS


Beer Street  and  Gin Lane , William Hogarth (1751)


Human lower leg anatomy


An AFO (ankle foot orthosis) brace is a type of orthotic used to support the foot and ankle.


Dynamic advanced orthosis for drop foot


Animation of the frontal lobe, shown in red


Animation of the cerebellum, shown in red


The M2 pathway is shown in red, originating in the pre-motor cortex. The PrL pathway is shown in purple, originating in the medial prefrontal cortex


Intermediate magnification  micrograph  showing giant cell arteritis in a  temporal artery  biopsy. The arterial lumen is seen on the left. A giant cell is seen on the right at the interface between the thickened  intima  and  media .   H&E stain


Histopathology of giant cell vasculitis in a cerebral artery. Elastica-stain.


Major Gulf War engagements in which DU rounds were used


Louis Jones Jr . claimed Gulf War syndrome as a defense in his murder trial


Lesions lips, patient with hemorrhagic hereditary telangiectasia.


Tongue telangiectases as seen in a person with hereditary hemorrhagic telangiectasia


A very large arteriovenous malformation in the left hemisphere (on the right in this image) of the brain.


Hereditary hemorrhagic telangiectasia has an autosomal dominant pattern of inheritance.


A schematic representation of the TGF-β signaling pathway. Endoglin (yellow) is needed for signalling. The ligand (blue) binds to the receptor complex; red indicates a type II receptor protein, which activates a type I receptor protein (turquoise) such as alk-1, which in turn phosphorylates a SMAD-based nuclear transcription factor (green and purple).


A vascular lesion in the digestive tract, being treated with argon plasma coagulation.


CT-scan of vascular malformations in the liver in a patient with hereditary hemorrhagic telangiectasia causing an inhomogeneous perfusion pattern.


The  Netherlands Antilles , where HHT is more common than anywhere in the world, located off the coast of Venezuela.


Foot showing features of HMSN:  pes cavus  and clawing of the toes


Myelinated neuron


Ankle foot orthosis


The  basal ganglia  are involved in hyperkinesia.


Samuel Alexander Kinnier Wilson , the neurologist most known for his description of what came to be known as  Wilson's disease .


A healthy, neuropathic, and myopathic electromyogram, respectively.


Scientifically accurate atomic model of the external structure of SARS-CoV-2. Each "ball" is an atom.


Structure of the olfactory epithelium. SARS-CoV-2 infects the support cells (sustentacular cells), which injures the olfactory neurons in the olfactory epithelium leading to loss of smell. New olfactory neurons regenerate from the basal cells.


Impact of COVID-19 on neurological and psychiatric outcomes in the subsequent 6 months compared with other respiratory tract infections [ 16 ]


The cerebellum is highlighted in purple.


A  radiography  during an intervention of  deep brain stimulation


Eukaryote cells sort misfolded proteins into two quality control compartments: JUNQ and IPOD, based on their ubiquitination state.


Eukaryote cells sort misfolded proteins, based on their ubiquitination state, into two quality control compartments:  1. JUNQ (green), which is tethered to the  nucleus  (orange) 2. IPOD(green), which is tethered to the  vacuole  (black shadow)


A JUNQ inclusion viewed by a ubiquitinated VHL protein(green), is tethered to the  nucleus  (orange).


An IPOD inclusion viewed by a non-ubiquitinated VHL protein(red), tethered to the  vacuole  (green).


' Graph 1'  Represents data that  shows how Lafora disease has been distributed throughout not just the United States but the world as a whole. This particular graph shows  250 families that have been affected by Lafora Disease. [ 19 ]


' Graph 2'  Represents data that shows how the gene mutation for both EPM2A and EPM2B has been distributed around the world. The data goes to show that there are more cases caused by EPM2B than there are for EPM2B (NHLRC1). [ 19 ]


Lafora disease has an  autosomal recessive  pattern of inheritance. [ 18 ]  EPM2A gene found on chromosome 6q24 and NHLRC1 gene found on chromosome 6p22.3. [ 20 ]


Gonzalo Rodríguez Lafora , discoverer of the disease


Two healthy mitochondria from mammalian lung tissue as shown by electron microscopy


The autosomal recessive pattern of inheritance seen in some cases of Leigh syndrome


The  X-linked recessive  pattern of inheritance seen occasionally in cases of Leigh syndrome


Chemical structure of methylprednisolone. Corticosteroids are used during acute multiple sclerosis relapses.


Disease-modifying treatments are expensive and most require frequent (up-to-daily) injections, under the skin or into the muscle. Newer treatments feature intravenous (IV) infusions (shown above) at 1 to 3-month intervals.


Injectable medications can produce irritation or bruises at injection site. The bruise depicted was produced by a subcutaneous injection.


Irritation zone after injection of glatiramer acetate.


Chemical structure of mitoxantrone


Supervised physical therapy may be helpful to overcome some symptoms.


Chemical structure of  alemtuzumab


Lateral cutaneous nerve of thigh  and other structures passing between the left inguinal ligament and ilium, frontolateral view of the right side of the pelvis.


Mevalonic acid


The biosynthesis of isoprenoids


Mevalonate pathway


Mevalonate kinase deficiency has an autosomal recessive pattern of  inheritance .


Amsler grid as it might appear to someone with micropsia as a result of  age-related macular degeneration .


An  MRI  image of a brain tumor occupying the left  temporal  and  parieto - occipital  regions of the brain.


Chilean writer Ana María Haebig has Moebius Syndrome


Sagittal  magnetic resonance imaging  scan showing a markedly underdeveloped ( hypoplastic ) tongue


Mentally disabled woman with features indicative of Muenke syndrome


Muenke Syndrome is inherited in an  autosomal dominant  pattern.


Typical time frames of post-exertional malaise after normal daily activities


Results of a study on the  quality of life  of individuals with ME/CFS, showing it to be lower than in 20 other chronic conditions


When people with ME/CFS exercise on consecutive days, their performance declines on the second day, unlike those with  unexplained chronic fatigue  (ICF).


Could You Have ME/CFS?  handout from the US Centers for Disease Control and Prevention


A heart rate monitor can be helpful for energy management.


Incidence rates by age and sex, from a 2014 study in Norway


Presentation of a petition to the  National Assembly for Wales  relating to ME support in South East Wales


The blue ribbon is used for ME/CFS awareness.


Graph of ME/CFS papers published by year:    Papers mentioning ME or CFS    Papers whose title mentions ME/CFS


According to a 1922  osteopath , the  Venus de Milo  was "neurasthenic as her stomach was not in the proper position". [ 13 ]


Comparison of brain tissue between healthy individual and Alzheimer's disease patient, demonstrating extent of neuronal death


Risks from viral exposures according to one biobank study [ 58 ]


A child with  Down syndrome


CT scan  showing  epidural hematoma , a type of traumatic brain injury (upper left)


MRI


Map of England


Café au lait spot  characteristic of NF1


Diagnostic criteria of neurofibromatosis type I, requiring at least 2 of the mentioned items. [ 6 ]


MRI image showing malignant peripheral nerve sheath tumor in the left tibia in neurofibromatosis type-1


NF-1 is inherited in an  autosomal dominant  fashion, although it can also arise due to spontaneous mutation.


NF-2 may be inherited in an  autosomal dominant  fashion, as well as through random mutation.


Micrograph  of a  schwannoma , a tumor seen in neurofibromatosis type II.  HPS stain .


Schwannoma of the N. Vestibularis


Meningiomas in a person with NFII


NF-2 Locus


Left image :  MRI  findings (T1-weighted images) in a patient with neurosacoidosis showing thickening of  infundibulum  and both  optic nerves  (white signal marked with yellow arrows; width 6 mm).   Right image : MRI brain with contrast showing near resolution of enhancement after treatment.


Nystagmus as seen in a case of  ocular albinism


Fast-phase horizontal eye movement vision


Fast-phase vertical eye movement vision


A diagram of the  caloric reflex test , which tests the  vestibulo-ocular reflex  (VOR) by irrigating the ear canal with warm or cold water to induce physiological nystagmus.


MRIs of a normal individual (left) and a patient with microcephaly caused by genetic mutation (right)


Electroencephalogram (EEG) displaying burst suppression patterns. Onset of bursts are indicated by solid arrows; offset, by open arrows. In both A and B, the interval between each vertical dotted line is one second


Figure 2: This image shows the three different types of aortic dissection.


Figure 3: A visualization of the aorta (4) in relation to the pulmonary artery (5).


The eponymous objects


Site of speech processes that sit on the Perisylvian Fissure


Man with facial paralysis on his right side


Image of arachnoid cyst


CT scan with MCA infarction


image of cerebral angiography


Middle cranial fossa


Image of brain MRI.


Friedrich Albert von Zenker


A mirror box used for treating phantom limbs, developed by V.S. Ramachandran


Structure of Venlafaxine


Misfolded proteins can form protein aggregates or  amyloid fibrils , get  degraded , or refold back to its  native structure .


Micrograph of amyloid in a section of  liver  that has been stained with the dye Congo red and viewed with crossed polarizing filters, yielding a typical orange-greenish birefringence. 20X microscope objective; the scale bar is 100 microns (0.1mm).


Micrograph of immunostained  α-synuclein  (brown) in  Lewy bodies  (large clumps) and Lewy neurites (thread-like structures) in the cerebral cortex of a patient with  Lewy body disease , a  synucleinopathy . 40X microscope objective.


Progressive neuropathy can lead to irreversible damage, early identification of asymptomatic neuropathy may prevent loss of limb.


Animals with "dumb" rabies appear depressed, lethargic, and uncoordinated


A young girl about to receive PEP after being bitten by an animal thought to be rabid


Map of rabies-free countries and territories


Rabies cases in humans and domestic animals – United States, 1938–2018


Two dogs with the paralytic, or dumb, form of rabies


Diagram illustrating the locations of extraocular muscles and ocular cranial nerves. Paresis of the oculomotor nerve (CNIII) reduces the strength of  medial rectus ,  superior rectus ,  inferior rectus , and  inferior oblique  muscles, while trochlear nerve (CNIV) and abducens nerve (CNVI) paralysis affect  superior oblique muscle  and  lateral rectus muscle  respectively.


Physical examination showing ophthalmoplegia affecting the left eye. The central image represents forward gaze while other images represents different direction of gaze. Drooping of eyelids  (ptosis ) and nonaligned eyes ( strabismus ) are observed, showing paresis of CNIII, CNIV and CNVI.


Artist's depiction of a scintillating scotoma, exhibiting a flashing visual pattern similar to  dazzle camouflage  used during WWI.


An artist's depiction of a scintillating scotoma with a bilateral arc


In teichopsia, migraine sufferers see patterns in the shape of the walls of a  star fort .


The vestibular system is stimulated through hanging equipment such as tire swings.


Human body temperature scale, showing the body temperature of what is considered hypothermia.


Hyperhidrosis


Location of the corpus callosum within the human brain.


Coronal sections of human brain labeling the basal ganglia.


Target molecules of botulinum (BoNT) and tetanus (TeNT) toxins inside the axon terminal. [1]


Insertion of electrode during surgery


Motor track


Baclofen


Doppler ultrasound of subclavian steal phenomenon


Angiogram of subclavian steal phenomenon before and after stent placement


CT angiography of subclavian steal phenomenon


Erythema marginatum


Penicillin


Lifecycle of  T. solium . Red arrows indicate pig; blue arrows human.


MRI sagittal image of sacral and dorso-lumbar perineural cysts.


Timothy syndrome has an autosomal-dominant pattern of inheritance.


Syndactyly  in a  2 + 1 / 2  -year old girl with Timothy syndrome


A reconstruction of the vertebral arteries from a CT scan, seen from the front. From the bottom, V1 is from the subclavian artery to the foramina, V2 is from the foramina to the second vertebra, V3 is between the foramina until entry into the skull, and V4 is inside the skull embedded in the  dura mater . They merge into the basilar artery, which then divides into the  posterior cerebral artery .


Magnetic resonance angiogram of the neck vessels in a person with Ehlers-Danlos syndrome type IV; it shows a dissection of the left internal carotid artery, dissection of both vertebral arteries in their V1 and V2 segments and a dissection of the middle and distal third of the right subclavian artery. Such striking episodes of dissection are typical for this "vascular" subtype of Ehlers-Danlos syndrome.


Aspirin (tablets pictured) is commonly used after stroke. In vertebral artery dissection it appears as effective as anticoagulation with warfarin.


Girl with Wilson's disease showing neurological symptoms


A brown ring on the edge of the iris ( Kayser–Fleischer ring ) is common in Wilson's disease, especially when neurological symptoms are present.


Wilson's disease has an autosomal recessive pattern of inheritance.


Normal absorption and distribution of copper: Cu = copper, CP =  ceruloplasmin , green = ATP7B carrying copper


Location of the basal ganglia, the part of the brain affected by Wilson's disease


Ceruloplasmin


Active electrolocation. Conductive objects concentrate the field and resistive objects spread the field.


Nervous system organization - the motor and sensory systems


An illustration of the route of ASMR's tingling sensation [ 1 ]


Virginia Woolf's novel  Mrs Dalloway  contains a passage describing something that may be comparable to ASMR.


Animal grooming has been interpreted as a form of bonding.


Search Examples of bitter compounds in BitterDB


A  2-D model  of cortical  sensory  homunculus


A 2-D cortical  motor  homunculus


3-D sensory and motor homunculus models at the  Natural History Museum, London


Flotation tank with flip top lid opened


The  elephantnose fish  is a weakly electric  mormyrid  fish which generates an  electric field  with its  electric organ  and then uses its electroreceptive  knollenorgans  and mormyromasts to locate nearby objects by the distortions they cause in the electric field. [ 1 ]


Hans Lissmann  discovered electroreception in 1950 through his observations of  Gymnarchus niloticus . [ 2 ]


Electric eels  create  electric fields  powerful enough to stun prey using modified  muscles . Some weakly electric knifefishes appear to mimic the electric eel's discharge patterns; this may be  Batesian mimicry , to deceive predators that they are too dangerous to attack. [ 20 ]


The  platypus  is a  monotreme  mammal that has secondarily acquired electroreception. Its receptors are arranged in stripes on its bill, giving it high sensitivity to the sides and below; it makes quick turns of its head as it swims to detect prey. [ 37 ] [ 38 ]


Arthropods  like these  northern prawn , and some mammals, detect water movement with sensory hairs such as  whiskers ,  bristles  or  antennae


Lateral line on an  Atlantic cod


Tactile receptors.


A child bites into a  watermelon , experiencing mouthfeel sensations such as juiciness


Schematic diagram of the experimental set-up in the rubber hand illusion task.


Superior colliculus


Light microscope photograph of a muscle spindle. HE stain.


Prismatic reversing glasses (upside down goggles with two prisms)


Modern version of inverting mirrors with harness


Mechanism of nociception via  sensory afferents


This diagram linearly (unless otherwise mentioned) tracks the projections of all known structures that allow for pain, proprioception, thermoception, and chemoception to their relevant endpoints in the human brain. Click to enlarge.


Example of a hot plate assay performed on a rat


Example of a traditional set-up for the tail flick assay


A US  Food and Drug Administration  sensory analyst sniffs  canned mackerel  to check for spoilage.


Portrait of  René Descartes  by  Jan Baptist Weenix , 1647–1649


Regions of the cerebral cortex associated with pain


Mechanism of nociceptive pain


The  breaking wheel  was a torture method used for  public execution  by breaking the bones of a criminal or  bludgeoning  them to death.


The  Mawé people  of Brazil intentionally use  bullet ant  stings as a  rite of passage  into manhood.


The second neuron in the figure depicts an encapsulated nerve ending.


The image on the left side depicts the dorsal column pathway for vibration perception.


The peripheral nervous system with an enlarged depiction of an afferent neuron.


The central nervous system


The  Necker cube  and  Rubin vase  can be perceived in more than one way.


Humans are able to make a very good guess on the underlying 3D shape category/identity/geometry given a silhouette of that shape.  Computer vision  researchers have been able to build computational models for perception that exhibit a similar behavior and are capable of generating and  reconstructing 3D shapes  from single or multi-view depth maps or silhouettes. [ 1 ]


Cerebrum lobes


Anatomy of the human ear. (The length of the auditory canal is exaggerated in this image.)    Brown is  outer ear .      Red is  middle ear .      Purple is  inner ear .


Though the phrase "I owe you" can be heard as three distinct words, a  spectrogram  reveals no clear boundaries.


Law of Closure. The human brain tends to perceive complete shapes even if those forms are incomplete.


Spinal cord tracts - tracts of the DCML pathway shown upper right.


Neural connections in the DCML pathway.


The first-order neuron is a  pseudounipolar neuron  (shown left), with a single  axon  originating from the  cell body  then splitting into two branches. The body is situated in the dorsal root ganglion, with one axon traveling peripherally to tissue, and one traveling into the dorsal column. On the right is a  bipolar neuron .


Prepulse inhibition: preceding stimulus attenuates the  startle response .


PPI and startle reflex apparatus for mice


PPI measurement in human.


Prey have adaptations such as  cryptic coloration  in this  Alaskan hare  which help them  avoid predators .


Experiments on  blue jays  suggest they form a search image for certain prey.


This  ladybeetle  ( Calvia decemguttata ) is easily spotted, but its conspicuous colors are a sign of its  unpalatability , with which experienced predators would probably be familiar.


Schematics and images of types of limb proprioceptor neurons in mammals (top) and insects (bottom) [ 1 ]


Graphical representation of  range fractionation . In this diagram, 10 sensory neurons respond to fraction of the entire range of intensities of stimulus (blue, bottom). Together, all 10 of these neurons comprise the range of perceived stimuli", which is all of the discernable stimulus intensities to the system. Neuron response is indicated by "Sensory Neuron Activity" (or, Action Potential Firing Rate). The range of a single sensory neuron is indicated in yellow. In this depiction, low-intensity stimuli (light blue, left) would activate a single sensory neuron, whereas high-intensity stimuli (dark blue, right) may activate 3-4 neurons. The collective firing pattern of the sensory neurons will inform the nervous system about the stimulus properties.


On center and off center  retinal ganglion cells  respond oppositely to light in the center and surround of their receptive fields. A strong response means high frequency firing, a weak response is firing at a low frequency, and no response means no action potential is fired.


A computer emulation of "edge detection" using retinal receptive fields. On-centre and off-centre stimulation is shown in red and green respectively.


Neurons of a convolutional layer (blue), connected to their receptive field (red)


CNN layers arranged in three dimensions


Sensation consists of signal collection and transduction.


Human power exponents and Steven's Power Law


Philippe Mercier -  The Sense of Taste - Google Art Project


The sense of smell. Bequest of  Mrs E.G. Elgar , 1945  Museum of New Zealand Te Papa Tongarewa .


Balance skill development in children


Balance training using  medicine balls


Diagram of  vestibular system


This figure shows nerve activity associated with rotational-induced  physiologic nystagmus  and spontaneous nystagmus resulting from a lesion of one labyrinth. Thin straight arrows show direction of slow components, thick straight arrows show direction of fast components, and curved arrows show direction of  endolymph  flow in the horizontal  semicircular canals . The three semicircular canals are marked AC (anterior canal), PC (posterior canal), and HC (horizontal canal).


This diagram linearly (unless otherwise mentioned) tracks the projections of all known structures that allow for balance and acceleration to their relevant endpoints in the human brain.


Another diagram showing neural pathway of  vestibular /balance system. Arrows show the direction of information relay.


Illustration of the flow of fluid in the ear, which in turn causes displacement of the top portion of the hair cells that are embedded in the jelly-like cupula. Also shows the  utricle  and  saccule  organs that are responsible for detecting linear acceleration, or movement in a straight line.


Vestibular sense system, the "sixth sense"


Sensory inclusive bag for people with  sensory processing disorders


Sensory inclusive bag contents:  Noise-cancelling headphones ,  KultureCity  VIP tag,  fidget toy  and verbal cue card


A subject wearing an electroencephalography cap, a conventional technique for measuring one's reactivity using sensory gating.


Ad hoc  use of  sensory deprivation ; using a  kippah  to block light during an unexpected moment of hypersensitivity.


CT scan  slice of the brain showing a right- hemispheric   ischemic  stroke (left side of image).


The cortical homunculus, or the visual representation of how your brain sees your body, was discovered by Wilder Penfield


The  visual system  and the  somatosensory system  are active even during  resting state fMRI


Activation and response in the sensory nervous system


The  human eye  is the first element of a  sensory system : in this case,  vision , for the  visual system .


Human  ear


Human nose


Human  tongue


Disability-adjusted life year  for sense organ diseases per 100,000 inhabitants in 2002. [ 29 ]      no data      less than 200      200-400      400-600      600-800      800-1000      1000-1200      1200-1400      1400-1600      1600-1800      1800-2000      2000-2300      more than 2300


1:posterior segment 2:ora serrata 3:ciliary muscle 4:ciliary zonules 5:Schlemm's canal 6:pupil 7:anterior chamber 8:cornea 9:iris 10:lens cortex 11:lens nucleus 12:ciliary process 13:conjunctiva 14:inferior oblique muscule 15:inferior rectus muscule 16:medial rectus muscle 17:retinal arteries and veins 18:optic disc 19:dura mater 20:central retinal artery 21:central retinal vein 22:optic nerve 23:vorticose vein 24:bulbar sheath 25:macula 26:fovea  27:sclera 28:choroid 29:superior rectus muscle 30:retina


Diagrammatic vertical section through the eye of teleost fish. Fish have a  refractive index  gradient within the lens which compensates for  spherical aberration . [ 4 ]  Unlike humans, most fish adjust  focus  by moving the lens closer or further from the  retina . [ 5 ]  Teleosts do so by contracting the retractor lentis muscle.


A  three-spined stickleback  with stained neuromasts


The shape of the  hammerhead shark 's head may enhance olfaction by spacing the nostrils further apart.


Electromagnetic field receptors (ampullae of Lorenzini) and motion detecting canals in the head of a shark


Active electrolocation. Conductive objects concentrate the field and resistive objects spread the field.


Hooked  sailfish


This figure depicts an example of combination of a forward model and an inverse model. Here the reference input is the target sensory state that controller (inverse model) will use to compute a motor command. The plant ( motor unit ) acts out the motor command which results in a new sensory state. This new sensory state can be compared to the state predicted by the forward model to  obtain an error signal. This error signal can be used to correct the internal model or the current movement.


Sensory-specific satiety is illustrated when diners at a buffet eat a larger quantity of food than those eating a single dish, even when the single dish is provided in quantities as much as the diner desires.


The sexual dimorphism in Bibionidae eyes is prominent, with the large dorsal eyes of the male (left) entirely absent in the female (right)


Parts of human spinal cord          1    central canal      2    posterior median sulcus      3    gray matter      4    white matter      5    dorsal root (left), dorsal root ganglion (right)      6    ventral root      7    fascicles      8    anterior spinal artery      9    arachnoid mater      10    dura mater


Sectional organization of spinal cord


Diagram of the spinal cord showing segments


Spinal cord segments and  spinal nerves , spinal cord detail, and spinal  meninges  and  conus medullaris


Spinal cord enlargements


Spinal cord seen in a midsection of a five-week-old embryo


Spinal cord seen in a midsection of a three-month-old fetus


Spinal cord tracts ascending tracts shown in blue


The anterior and lateral spinothalamic tracts labelled at lower right as tracts of the anterolateral system.


Location of visual, auditory and somatosensory perception in the superior colliculus of the brain. Overlapping of these systems creates multisensory space.


Schematic diagram of the human eye.


Diagram of the human ear.


The prominent barcode pattern on this  Ferrari F10   Formula 1  car served as advertising for  Marlboro .


Taste bud


The diagram above depicts the signal transduction pathway of the sweet taste. Object A is a taste bud, object B is one taste cell of the taste bud, and object C is the neuron attached to the taste cell. I. Part I shows the reception of a molecule. 1. Sugar, the first messenger, binds to a protein receptor on the cell membrane. II. Part II shows the transduction of the relay molecules. 2. G Protein-coupled receptors, second messengers, are activated. 3. G Proteins activate adenylate cyclase, an enzyme, which increases the cAMP concentration. Depolarization occurs. 4. The energy, from step 3, is given to activate the K+, potassium, protein channels.III. Part III shows the response of the taste cell. 5. Ca+, calcium, protein channels is activated.6. The increased Ca+ concentration activates neurotransmitter vesicles. 7. The neuron connected to the taste bud is stimulated by the neurotransmitters.


The diagram depicts the signal transduction pathway of the sour or salty taste. Object A is a taste bud, object B is a taste receptor cell within object A, and object C is the neuron attached to object B.  I. Part I is the reception of hydrogen ions or sodium ions.  1. If the taste is sour, H +  ions, from acidic substances, pass through H +  channels. Depolarization takes place  II. Part II is the transduction pathway of the relay molecules. 2. Cation, such as K + , channels are opened.  III. Part III is the response of the cell.  3. An influx of Ca +  ions is activated.  4. The Ca +  activates neurotransmitters.  5. A signal is sent to the neuron attached to the taste bud.


The diagram depicted above shows the signal transduction pathway of the bitter taste. Bitter taste has many different receptors and signal transduction pathways. Bitter indicates poison to animals. It is most similar to sweet. Object A is a taste bud, object B is one taste cell, and object C is a neuron attached to object B. I. Part I is the reception of a molecule.1. A bitter substance such as quinine, is consumed and binds to G Protein-coupled receptors.II. Part II is the transduction pathway 2. Gustducin, a G protein second messenger, is activated. 3. Phosphodiesterase, an enzyme, is then activated. 4. Cyclic nucleotide, cNMP, is used, lowering the concentration 5. Channels such as the K+, potassium, channels, close. III. Part III is the response of the taste cell. 6. This leads to increased levels of Ca+. 7. The neurotransmitters are activated. 8. The signal is sent to the neuron.


Taste buds and papillae of the human tongue


Taste receptors of the human tongue


Signal transduction  of taste receptors


Active brain areas in taste perception


This diagram linearly (unless otherwise mentioned) tracks the projections of all known structures that allow for taste to their relevant endpoints in the human brain.


Thalamic nuclei.  Metathalamus  labelled MTh. (Left thalamus viewed from left.)


Nuclei of right thalamus (viewed from above right)


Medial nuclei of the left thalamus.  Key: CeM  Central Medial . CL  Central Lateral . CM  CentroMedian . MD  Medial Dorsal . MV MedioVentral= Reuniens . Pf  Parafascicular . (Lateral view shows sagittal section through left thalamus)


Lateral nuclei of the left thalamus.  Key: VA  Ventral Anterior . VL  Ventral Lateral . VM  Ventral Medial . VPI Ventral PosteroInferior. VPL  Ventral PosteroLateral . VPM  Ventral PosteroMedial . (Medial view shows sagittal section through left thalamus.)


The thalamus is connected to the spinal cord via the  spinothalamic tract


Positions of the pit organs (arrowed in red) on a python, relative to its nostril (black arrow)


The Thinker  by  Auguste Rodin  (1840–1917) in the garden of the  Musée Rodin , Paris


Man thinking on a train journey


A muscle spindle, with γ motor and Ia sensory fibers


Human vestibular system of the  semicircular canals  in the inner ear


Cochlea and vestibular system


Push-pull system of the semicircular canals, for a horizontal head movement to the right.


The vestibulo-ocular reflex. A rotation of the head is detected, which triggers an inhibitory signal to the  extraocular muscles  on one side and an excitatory signal to the muscles on the other side. The result is a compensatory movement of the eyes.


Neural pathway  of the vestibular system


This diagram linearly (unless otherwise mentioned) tracks the projections of all known structures that allow for vision to their relevant endpoints in the human brain. Click to enlarge the image.


Representation of optic pathways from each of the 4 quadrants of view for both eyes simultaneously


The  human eye  (horizontal section) The image projected onto the retina is inverted due to the optics of the eye.


S. Ramón y Cajal ,  Structure of the  Mammalian  Retina, 1900


Information flow from the  eyes  (top), crossing at the  optic chiasma , joining left and right eye information in the  optic tract , and layering left and right visual stimuli in the  lateral geniculate nucleus .  V1  in red at bottom of image. (1543 image from  Andreas Vesalius '  Fabrica )


Six layers in the  LGN


Scheme of the  optic tract  with image being decomposed on the way, up to simple cortical cells (simplified)


Visual cortex :  V1; V2; V3; V4; V5 (also called MT)


Visual cortex is active even during  resting state fMRI .


Intraparietal sulcus  (red)


Visual pathway lesions    From top to bottom:   1. Complete loss of vision, right eye   2.  Bitemporal hemianopia    3.  Homonymous hemianopsia    4.  Quadrantanopia    5&6. Quadrantanopia with  macular sparing


Figure 2.  Example of bifurcating axons in the  optic chiasm  (Type II) of a rabbit. a,b,c: bifurcating optic fibres. c: fibre bifurcating in the two opposite optic tracts. d. Commissure of Gudden. e. Fibres that continue in a different depth. (from: Cajal, [ 5 ]  Fig. 6)


Figure 3.  The decussation of the optic radiation in the cortex is an example of a type IV crossing


Peripheral nervous system box diagram


Langley's Classification Tree from his 1921 book  The Autonomic Nervous System


Myelinated   GS efferent fiber  leaving cell body of motor neuron to form a neuromuscular junction


Nerve cell and organization


Cross-section of a nerve


Micrograph  demonstrating  perineural invasion  of  prostate cancer .  H&E stain .


Spinal nerve


Cervical plexus


Anatomical illustration of the  brachial plexus  with areas of roots, trunks, divisions and cords marked. Clicking on names of branches will link to their Wikipedia entry.


The  lumbar plexus  and its branches.


Plan of sacral and coccygeal plexuses.


Distribution of the areas of the sensory roots upon the surface of the body


3D Medical Animation still shot of Lumbosacral Plexus


Typical spinal nerve location


Scheme showing structure of a typical spinal nerve 1.  Somatic efferent . 2.  Somatic afferent . 3,4,5.  Sympathetic efferent . 6,7.  Autonomic afferent .


Cervical nerves


Lumbar plexus and branches


Plan of sacral and pudendal plexuses


Areas of distribution of the cutaneous branches of the posterior divisions of the spinal nerves. The areas of the medial branches are in black, those of the lateral in red


Dissection of a human brain with labels showing the clear division between white and gray matter.


Diagram of the columns and of the course of the fibers in the spinal cord. Sensory synapses occur in the dorsal spinal cord (above in this image), and motor nerves leave through the ventral (as well as lateral) horns of the spinal cord as seen below in the image.


Different ways in which the CNS can be activated without engaging the cortex, and making us aware of the actions. The above example shows the process in which the pupil dilates during dim light, activating neurons in the spinal cord. The second example shows the constriction of the pupil as a result of the activation of the Eddinger-Westphal nucleus (a cerebral ganglion).


A map over the different structures of the nervous systems in the body, showing the CNS,  PNS ,  autonomic nervous system , and  enteric nervous system .


Human brain in the  sagittal plane


Ventricles of the brain


Tau protein  disorders cause  microtubule  destruction and formation of  neurofibrillary tangles .


Major dopamine pathways. As part of the  reward pathway , dopamine is manufactured in nerve cell bodies located within  VTA  and is released in the  nucleus accumbens  and the  prefrontal cortex . The motor functions of dopamine are linked to a separate pathway, with cell bodies in the  substantia nigra  that manufacture and release dopamine into the  striatum .


Dopamine and serotonin functions and pathways


Expression of  glutamate transporter 1  in  glial cell  facilitates reuptake of glutamate and decreases extracellular glutamate concentration


The cerebrospinal fluid circulates in the  subarachnoid space  around the brain and  spinal cord , and in the  ventricles  of the brain


Life expectancy in the USA by race [ 97 ]


Life expectancy in the USA by race and sex, with calculated sex gap [ 97 ]


Astrocytes (green) in the context of neurons (red) in a mouse cortex  cell culture


23-week-old fetal brain culture human astrocyte


Astrocytes (red-yellow) among neurons (green) in the living cerebral cortex


Astrocytes are depicted in red. Cell nuclei are depicted in blue. Astrocytes were obtained from brains of newborn mice.


Metabolic interactions between astrocytes and neurons [ 17 ]


Astrocyte endfeet processes surrounding a blood vessel


Fig. 6 The conjectured switching role of glia in the biological neural detection scheme as suggested by Nossenson et al. [ 37 ] [ 38 ]


Part of a network of  capillaries  supplying brain cells


The astrocytes type 1 surrounding capillaries in the brain


Sketch showing constitution of blood vessels inside the brain


Updated leptin–melanocortin model


Figure 6-1(a).  (Panel A) Expression of polysialic acid form of neural cell adhesion molecule (PSA-NCAM) in the hippocampus of rats that were irradiated (IR) with 2.5 Gy of 56Fe high-energy radiation and control subjects as measured by % density/field area measured. (Panel B) PSA-NCAM staining in the dentate gyrus of representative irradiated (IR) and control (C) subjects at 5x magnification. [ 44 ]


Figure 6-1(b).  Numbers of proliferating cells (left panel) and immature neurons (right panel) in the dentate SGZ are significantly decreased 48 hours after irradiation. Antibodies against Ki-67 and doublecortin (Dcx) were used to detect proliferating cells and immature neurons, respectively. Doses from 2 to 10 Gy significantly (p < 0.05) reduced the numbers of proliferating cells. Immature neurons were also reduced in a dose-dependent fashion (p<0.001). Each bar represents an average of four animals; error bars, and standard error. [ 41 ]


Figure 6-2.  Dose response for oxidative stress after 56Fe-ion irradiation. Hippocampal precursors that are subjected to 56Fe-ion irradiation were analyzed for oxidative stress 6 hours after exposure. At doses ≤1 Gy a linear dose response for the induction of oxidative stress was observed. At higher 56Fe doses, oxidative stress fell to values that were found using lower-LET irradiations (X rays, protons). Experiments, which represent a minimum of three independent measurements (±SE), were normalized against unirradiated controls set to unity. ROS levels induced after 56Fe irradiation were significantly (P < 0.05) higher than controls. [ 49 ]


Figure 6-3.  ED 50  for CTA as a function of LET for the following radiation sources:  40 Ar = argon ions,  60 Co = Cobalt-60 gamma rays, e −  = electrons,  56 FE = iron ions,  4 He = helium ions, n 0  = neutrons,  20 Ne = neon ions. [ 62 ]


Figure 6-4.  Radiation-induced disruption in CTA. This figure shows the relationship between exposure to different energies of  56 FE and  28 Si particles and the threshold dose for the disruption of amphetamine-induced CTA learning. Only a single energy of  48 Ti particles was tested. The threshold dose (cGy) for the disruption of the response is plotted against particle LET (keV/μm). [ 66 ]


Figure 6-5.jpg  High-LET radiation effects on operant response. This figure shows the relationship between the exposure to different energies of  56 Fe and  28 Si particles and the threshold dose for the disruption of performance on a food-reinforced operant response. Only a single energy of  48 Ti particles was tested. The threshold dose (cGy) for the disruption of the response is plotted against particle LET (keV/μm). [ 66 ]


Figure 6-6.  Brain-region-specific calcium-dependent protein kinase C expression was assessed in control and irradiated rats using standard Western blotting procedures. Values are means ± SEM (standard error of mean). [ 69 ]


Figure 6-7.  LET dependence of RBE of radiation in producing emesis or retching in a ferret. B = bremsstrahlung; e −  =  electrons; P = protons;  60 Co = cobalt gamma rays; n 0  = neutrons; and  56 Fe = iron.


Figure 6-9.  Model of plaque formation and neuronal death in Alzheimer's disease. From Edelstein-Keshet and Spiros, 2002: Top row: Formation of a plaque and death of neurons in the absence of glial cells, when fibrous amyloid is the only injurious influence. The simulation was run with no astrocytes or microglia, and the health of neurons was determined solely by the local fibrous amyloid. Shown above is a time sequence (left to right) of three stages in plaque development, at early, intermediate, and advanced stages. Density of fibrous deposit is represented by small dots and neuronal health by shading from white (healthy) to black (dead). Note radial symmetry due to simple diffusion. Bottom row: Effect of microglial removal of amyloid on plaque morphology. Note that microglia (small star-like shapes) are seen approaching the plaque (via chemotaxis to soluble amyloid, not shown). At a later stage, they have congregated at the plaque center, where they adhere to fibers. As a result of the removal of soluble and fibrous amyloid, the microglia lead to irregular plaque morphology. Size scale: In this figure, the distance between the small single dots (representing low-fiber deposits) is 10 mm. Similar results were obtained for a 10-fold scaling in the time scale of neuronal health dynamics. [ 71 ]


A flask containing human cerebral organoids


Instructive growth factors regulating fate decisions in embryonic NCSCs


This flow chart outlines the basic steps to create a cerebral organoid. The process takes a span of months and the size of the organoid is limited to the availability of nutrients.


An efference copy is used to generate the predicted sensory input which estimates the (somato)sensory consequences of a motor command (top row). The sensory consequences of the executed motor command (bottom row) are used to compare with the corollary discharge to inform the CNS about external actions.


Efference copies as used in speech production: motor and auditory efference copies serve to allow for rapid comparison with motor and auditory consequences.


In the  mormyrid electric fish  corollary discharges enables the  knollenorgan  sensor (KS) to detect the  electric organ discharges  of other fish without also detecting their own self generated electric organ discharges.


Astrocytes stained for GFAP (green) and aquaporin-4 (purple)


Meningeal lymphatic vessels run parallel to the  dural venous sinuses .


Example of a meningeal whole-mount taken from an adult mouse. [ 12 ]  Laying the whole-mount on a glass slide allows for histological analysis of the entire dura, including the superior sagittal and transverse sinuses.


Human meningeal lymphatic vessels using  magnetic resonance imaging  (MRI) with  gadobutrol  as  constrast agent  which in the dura mater leaks out of blood vessels and collects inside lymphatic vessels, that show up as bright white areas on brain scans. [ 13 ] [ 14 ]


Confocal micrograph of meningeal lymphatic vessels and trafficking immune cells. LYVE1 (green), CD3e (red), and DAPI (blue) are shown.


Cross-section of the middle pons (at the level of cranial nerve V).


Cross-section of the inferior pons (at the level of the facial genu).


History of cerebral organoid to myelinoid generation protocols


General workflow for generating myelin organoids.


Timeline of small molecules & growth factors for myelinoid differentiation and generation.


Precentral gyrus sensory homunculus


Facial view of an infant with macrocephaly


Diagram illustrating the theorized causes of NAA accumulation in spongy degeneration patients and its consequences


Small volume of amniotic fluid is extracted via  amniocentesis  with a  syringe .


Molecular view of gene therapy using an adenovirus vector


The iceberg metaphor proposed by G. T. Fechner is often used to provide a visual representation of Freud's theory that most of the human mind operates unconsciously. [ 31 ]