---
license: cc-by-4.0
library_name: xgboost
tags:
  - neuroscience
  - electrophysiology
  - neuropixels
  - brain-region-classification
  - international-brain-lab
---

# Ephys Atlas region classifier (2026_W32, Cosmos)

Predicts the **brain region of each Neuropixels recording channel** from electrophysiological
features alone -- no histology required. Trained by the
[International Brain Laboratory](https://www.internationalbrainlab.com/) on the Ephys Atlas
feature release `2026_W32`.

> **What you can and cannot do without IBL access.** The *model* runs for anyone. Computing
> the *input features* from raw Neuropixels data needs `ibllib` / `ibl-neuropixel`, and the
> raw data itself is IBL-hosted. To try the model immediately, use the bundled sample under
> `example/` -- no account, no raw data, no S3.

## Quickstart

```python
import pandas as pd
from ephysatlas import load_pretrained

model = load_pretrained("int-brain-lab/ea-decoder-channel-xgboost", revision="2026_W32")
df = pd.read_parquet("example/features_sample.parquet")   # or your own features
out = model.predict(df)
print(out[["predicted_acronym", "prediction_probability", "fold_agreement"]].head())
```

`load_pretrained` is the entry point for every ephysatlas model, whatever its family — it reads
`ephysatlas_model.json` and returns the right wrapper. Use it rather than importing a concrete
class, so your code keeps working as the package evolves.

`predict` returns one row per input channel, indexed identically to the input:
`predicted_acronym`, its Allen `predicted_atlas_id`, the fold-averaged
`prediction_probability`, a `fold_agreement` column (fraction of the 5 folds voting
for the winner -- the natural uncertainty signal), and a `p_<acronym>` column per class.

The prediction columns are namespaced so that `df.join(out)` works: the feature table already
carries histology-derived `acronym` / `atlas_id` columns, and predictions must not shadow them.

## Inputs

- **50 features**, listed in `ephysatlas_model.json` under `inputs.features`. Every
  one must be present; `predict` raises and names anything missing.
- Indexed by `(pid, channel)`, one row per recording channel.
- **Must be the denoised aggregated features of vintage `2026_W32`** -- that is, the
  `raw_ephys_features_denoised.pqt` table produced by the Ephys Atlas aggregation pipeline,
  as loaded by `ephysatlas.data.read_features_from_disk`. Units are baked into that table by
  the pipeline (RMS features in dB, `spike_count` in log2), so feeding raw features, or
  features from a vintage whose units differ, produces confident nonsense. Run
  `model.selftest()` to confirm your install reproduces the shipped output before trusting it.

## Performance

Pooled out-of-fold accuracy: **0.5962** over 13 Cosmos regions,
765 insertions. Splits are by insertion (`pid`), so no channel from a test
insertion appears in training. See `confusion_matrix.png`.

## Limitations

- Trained on IBL Neuropixels 1.0 recordings in mouse. Transfer to NP2, other species or
  other rigs is untested.
- Coverage follows IBL brain-wide-map targeting; rare regions are under-represented.
- `Cosmos` is a coarse parcellation. Predictions are per-channel and spatially
  unregularised -- neighbouring channels can disagree.
- Known-misaligned insertions were excluded from training.

## Reproducibility

**Pin the revision.** `revision="2026_W32"` is an immutable tag. Omitting `revision` resolves
to `main`, which tracks whichever model is currently recommended and *will* change when a new
feature vintage is published — fine for a first look, not for anything you publish or re-run.

`ephysatlas_model.json` records the training-time `environment` (xgboost, scikit-learn, numpy,
ephysatlas, python) and `random_seed`. Verify your install reproduces the shipped output:

```python
model.selftest()
```

Note `scikit-learn<1.9` is required (1.9 broke `OneToOneFeatureMixin.get_feature_names_out`,
which the feature transformer relies on).

## Citation

Please cite the International Brain Laboratory Ephys Atlas. Model id `2026_W32_Cosmos_guiltless-orange-mallard`,
feature vintage `2026_W32`.