Neuropixels Analysis

Neuropixels Data Analysis

Overview

Toolkit for analyzing Neuropixels high-density neural recordings using current best practices from SpikeInterface, the Allen Institute, and the International Brain Laboratory (IBL). It covers the full workflow from raw data to publication-ready curated units.

All examples use the real SpikeInterface API (spikeinterface.full as si) plus the companion curation module (spikeinterface.curation as sc). The skill ships runnable scripts in scripts/ and a copy-and-edit template in assets/ that implement this workflow directly on top of SpikeInterface — there is no separate package to install beyond the dependencies listed under Installation.

When to Use This Skill

This skill should be used when:

• Working with Neuropixels recordings (.ap.bin, .lf.bin, .meta files)
• Loading data from SpikeGLX, Open Ephys, or NWB formats
• Preprocessing neural recordings (filtering, common reference, bad-channel detection)
• Detecting and correcting motion/drift
• Running spike sorting (Kilosort4, SpykingCircus2, Mountainsort5, Tridesclous2)
• Computing quality metrics (SNR, ISI violations, presence ratio, amplitude cutoff)
• Curating units (threshold-based, model-based, or AI-assisted)
• Creating visualizations and exporting to Phy or NWB

Supported Hardware & Formats

Quick Start

Import and configure parallel processing

import spikeinterface.full as si

# Global job kwargs are reused by all parallelizable steps
si.set_global_job_kwargs(n_jobs=-1, chunk_duration="1s", progress_bar=True)

Loading data

# Inspect available streams first
stream_names, stream_ids = si.get_neo_streams("spikeglx", "/path/to/run_g0/")
print(stream_names)  # e.g. ['imec0.ap', 'imec0.lf', 'nidq']

# SpikeGLX (most common) — select the AP stream by name
recording = si.read_spikeglx("/path/to/run_g0/", stream_name="imec0.ap", load_sync_channel=False)

# Open Ephys
recording = si.read_openephys("/path/to/Record_Node_101/")

# For quick iteration, slice the first 60 s
fs = recording.get_sampling_frequency()
recording_sub = recording.frame_slice(0, int(60 * fs))

Full pipeline (bundled script)

The repository ships an end-to-end pipeline built on SpikeInterface:

python scripts/neuropixels_pipeline.py /path/to/spikeglx/data output/ --sorter kilosort4 --curation allen

It performs load → preprocess → drift check → optional motion correction → sorting → postprocessing → quality metrics → curation → export. Read the steps below to run them interactively or customize the pipeline.

Standard Analysis Workflow

1. Preprocessing

Recommended chain, following the SpikeInterface Neuropixels how-to (IBL-style destriping with channel removal + common reference):

rec = si.highpass_filter(recording, freq_min=400.0)
bad_channel_ids, channel_labels = si.detect_bad_channels(rec)
rec = rec.remove_channels(bad_channel_ids)
rec = si.phase_shift(rec)  # ADC phase correction (Neuropixels 1.0)
rec = si.common_reference(rec, operator="median", reference="global")

Save the preprocessed recording (Kilosort needs a binary file, and it speeds up reuse):

rec = rec.save(folder="preprocessed/", format="binary")

2. Check and correct drift

Always inspect drift before sorting:

from spikeinterface.sortingcomponents.peak_detection import detect_peaks
from spikeinterface.sortingcomponents.peak_localization import localize_peaks

noise_levels = si.get_noise_levels(rec, return_in_uV=False)
peaks = detect_peaks(rec, method="locally_exclusive", noise_levels=noise_levels,
                     detect_threshold=5, radius_um=50.0)
peak_locations = localize_peaks(rec, peaks, method="center_of_mass")

# Visualize the drift raster
si.plot_drift_raster_map(peaks=peaks, peak_locations=peak_locations,
                         recording=rec, clim=(-50, 50))

Apply correction if needed (presets: rigid_fast, kilosort_like, nonrigid_accurate, nonrigid_fast_and_accurate, dredge, dredge_fast):

rec_corrected = si.correct_motion(rec, preset="nonrigid_fast_and_accurate", folder="motion/")

3. Spike sorting

# Kilosort4 (recommended, requires a CUDA GPU)
sorting = si.run_sorter("kilosort4", rec_corrected, folder="ks4_output")

# CPU alternatives (internally developed, no external install)
sorting = si.run_sorter("spykingcircus2", rec_corrected, folder="sc2_output")
sorting = si.run_sorter("tridesclous2", rec_corrected, folder="tdc2_output")
sorting = si.run_sorter("mountainsort5", rec_corrected, folder="ms5_output")

# External sorters can run in containers without local install
sorting = si.run_sorter("kilosort2_5", rec_corrected, folder="ks25_output", docker_image=True)

print(si.installed_sorters())

Note: run_sorter uses the folder= argument. The older output_folder= is deprecated.

4. Postprocessing

analyzer = si.create_sorting_analyzer(sorting, rec_corrected, sparse=True,
                                      format="binary_folder", folder="analyzer/")

analyzer.compute("random_spikes", method="uniform", max_spikes_per_unit=500)
analyzer.compute("waveforms", ms_before=1.0, ms_after=2.0)
analyzer.compute("templates", operators=["average", "std"])
analyzer.compute("noise_levels")
analyzer.compute("spike_amplitudes")
analyzer.compute("correlograms", window_ms=50.0, bin_ms=1.0)
analyzer.compute("unit_locations", method="monopolar_triangulation")
analyzer.compute("template_similarity")

metric_names = ["firing_rate", "presence_ratio", "snr", "isi_violation", "amplitude_cutoff"]
analyzer.compute("quality_metrics", metric_names=metric_names)
metrics = analyzer.get_extension("quality_metrics").get_data()

5. Curation by metric thresholds

# Allen-style query (note: column is isi_violations_ratio)
query = "(amplitude_cutoff < 0.1) & (isi_violations_ratio < 0.5) & (presence_ratio > 0.9)"
good_unit_ids = metrics.query(query).index.values

For reusable, multi-threshold logic with allen / ibl / strict presets, use the bundled scripts/compute_metrics.py. See references/AUTOMATED_CURATION.md for details and the Bombcell / UnitMatch tools.

6. Model-based curation (UnitRefine)

SpikeInterface can apply pretrained machine-learning classifiers from Hugging Face via the spikeinterface.curation module. The UnitRefine models were trained on real Neuropixels data (V1, SC, ALM):

import spikeinterface.curation as sc

# 1) noise vs neural
noise_labels = sc.model_based_label_units(
    sorting_analyzer=analyzer,
    repo_id="SpikeInterface/UnitRefine_noise_neural_classifier",
    trust_model=True,
)
neural = analyzer.remove_units(noise_labels[noise_labels["prediction"] == "noise"].index)

# 2) single-unit (sua) vs multi-unit (mua) on the surviving units
sua_mua_labels = sc.model_based_label_units(
    sorting_analyzer=neural,
    repo_id="SpikeInterface/UnitRefine_sua_mua_classifier",
    trust_model=True,
)

Each call returns a DataFrame with prediction and probability (confidence) per unit. trust_model=True (or an explicit trusted=[...] list) is required to load the .skops model — only load models from sources you trust. Models trained on other brain areas/datasets may not transfer; validate against a manually labelled subset.

7. AI-assisted curation (for uncertain units)

When running inside an agent such as Cursor or Claude Code, the agent can directly inspect waveform/correlogram plots and give an expert read — no API setup required. Generate plots and ask the agent to assess isolation quality.

For programmatic vision-model access, read API keys from the environment — never hardcode credentials in analysis scripts (they leak into version control and logs):

import os
from anthropic import Anthropic

client = Anthropic(api_key=os.environ["ANTHROPIC_API_KEY"])  # set this in your shell, not in code

See references/AI_CURATION.md for the full pattern (rendering a unit summary image, building the prompt, and parsing the response).

8. Export results

# Keep only good units, then export
analyzer_clean = analyzer.select_units(good_unit_ids, folder="analyzer_clean/", format="binary_folder")

# Phy for manual review
si.export_to_phy(analyzer_clean, output_folder="phy_export/",
                 compute_pc_features=True, compute_amplitudes=True)

# Figures report
si.export_report(analyzer_clean, "report/", format="png")

# NWB
from spikeinterface.exporters import export_to_nwb
export_to_nwb(analyzer_clean, "output.nwb")

# Metrics table
metrics.to_csv("quality_metrics.csv")

Common Pitfalls and Best Practices

1. Always check drift before spike sorting — drift > ~10 μm meaningfully degrades quality.
2. Use phase_shift for Neuropixels 1.0 to correct ADC sampling offsets.
3. Save the preprocessed recording with rec.save(folder=...) to avoid recomputation (Kilosort also needs a binary file).
4. Use a GPU for Kilosort4 — it is far faster than CPU sorters.
5. Review uncertain units — automated/model-based curation is a starting point, not a verdict.
6. Combine approaches — thresholds for clear cases, model/AI for borderline units.
7. Document thresholds and model repo IDs for reproducibility.
8. Export to Phy for critical experiments — human oversight is valuable.

Key Parameters to Adjust

Preprocessing

• freq_min: highpass cutoff (300–400 Hz typical)
• detect_bad_channels: returns (bad_channel_ids, channel_labels)

Motion Correction

• preset: nonrigid_fast_and_accurate (balanced), nonrigid_accurate (severe drift), dredge (state of the art)

Spike Sorting (Kilosort4)

• batch_size: samples per batch (60000 default)
• nblocks: drift blocks (increase for long, drifty recordings)
• Th_universal / Th_learned: detection thresholds (lower = more spikes)

Quality Metrics

• snr: signal-to-noise cutoff (3–5 typical)
• isi_violations_ratio: refractory violations (0.01–0.5)
• presence_ratio: recording coverage (0.5–0.95)

Bundled Resources

scripts/explore_recording.py

Quick inspection of a recording (streams, channels, duration, bad channels):

python scripts/explore_recording.py /path/to/data

scripts/preprocess_recording.py

Automated preprocessing:

python scripts/preprocess_recording.py /path/to/data --output preprocessed/

scripts/run_sorting.py

Run spike sorting:

python scripts/run_sorting.py preprocessed/ --sorter kilosort4 --output sorting/

scripts/compute_metrics.py

Compute quality metrics and apply curation:

python scripts/compute_metrics.py sorting/ preprocessed/ --output metrics/ --curation allen

scripts/export_to_phy.py

Export to Phy for manual curation:

python scripts/export_to_phy.py metrics/analyzer --output phy_export/

scripts/neuropixels_pipeline.py

Complete end-to-end pipeline (see Quick Start).

assets/analysis_template.py

Complete, editable analysis template. Copy and customize:

cp assets/analysis_template.py my_analysis.py
# Edit the PARAMETERS section, then run
python my_analysis.py

Detailed Reference Guides

Installation

Requires Python ≥ 3.10. Using uv is recommended.

# Core packages (SpikeInterface bundles the curation/model tooling)
uv pip install "spikeinterface[full]" probeinterface neo

# Spike sorters
uv pip install kilosort          # Kilosort4 (CUDA GPU required)
uv pip install spykingcircus     # SpykingCircus (legacy; SpykingCircus2 ships with SpikeInterface)
uv pip install mountainsort5     # Mountainsort5 (CPU)

# Model-based curation (UnitRefine) downloads from Hugging Face
uv pip install "huggingface_hub" skops

# Optional: AI-assisted visual curation
uv pip install anthropic

# Optional: IBL tools and Bombcell
uv pip install ibl-neuropixel ibllib bombcell

For reproducible environments, pin versions (current as of 2026-06: spikeinterface==0.104.3, kilosort==4.1.7, probeinterface==0.3.2, neo==0.14.4). Unpinned installs are fine for quick experimentation but should be pinned in production pipelines.

Project Structure

project/
├── raw_data/
│   └── recording_g0/
│       └── recording_g0_imec0/
│           ├── recording_g0_t0.imec0.ap.bin
│           └── recording_g0_t0.imec0.ap.meta
├── preprocessed/           # Saved preprocessed recording
├── motion/                 # Motion estimation results
├── sorting_output/         # Spike sorter output
├── analyzer/               # SortingAnalyzer (waveforms, metrics)
├── phy_export/             # For manual curation
├── ai_curation/            # AI analysis reports
└── results/
    ├── quality_metrics.csv
    ├── curation_labels.json
    └── output.nwb

Additional Resources

• SpikeInterface Docs: https://spikeinterface.readthedocs.io/
• Neuropixels Tutorial: https://spikeinterface.readthedocs.io/en/stable/how_to/analyze_neuropixels.html
• Model-based Curation Tutorial: https://spikeinterface.readthedocs.io/en/stable/tutorials/curation/plot_1_automated_curation.html
• UnitRefine Models (Hugging Face): https://huggingface.co/SpikeInterface
• Kilosort4 GitHub: https://github.com/MouseLand/Kilosort
• IBL Neuropixel Tools: https://github.com/int-brain-lab/ibl-neuropixel
• Allen Institute ecephys: https://github.com/AllenInstitute/ecephys_spike_sorting
• Bombcell (Automated QC): https://github.com/Julie-Fabre/bombcell
• Awesome Neuropixels: https://github.com/Julie-Fabre/awesome_neuropixels