Accurate Localization of Linear Probe Electrode Arrays across Multiple Brains

Area of Science:

• Neuroscience
• Electrophysiology
• Brain Mapping

Background:

• High-density linear electrode arrays, like Neuropixels probes, enable multi-area recordings in rodent brains.
• Aligning recordings across sessions and animals to a standardized coordinate system is essential for data collation.
• Accurate electrode localization is critical for interpreting electrophysiological data within specific brain structures.

Purpose of the Study:

• To evaluate and compare two common workflows for localizing electrodes from linear probe recordings within standardized brain coordinates.
• To assess the accuracy of electrode localization using imaging and atlas registration techniques.
• To validate the localization accuracy using groundtruth experiments with optogenetically tagged neural activity.

Main Methods:

• Utilized two distinct workflows: one based on tissue clearing and selective plane illumination microscopy (SPIM), and another using serial block-face two-photon (SBF2P) microscopy.
• Reconstructed 3D probe tracks from fluorescent imaging of brain tissue.
• Employed electrophysiological features and atlas registration to anchor electrodes to specific brain locations.
• Conducted groundtruth experiments by optogenetically labeling motor cortex outputs (ChR2 and fluorescent protein).

Main Results:

• Both SPIM and SBF2P workflows demonstrated high accuracy in localizing electrodes.
• Groundtruth experiments confirmed sub-0.1-mm accuracy for electrode localization in targeted brain regions.
• Independent localization of light-evoked electrical activity and fluorescence validated the precision of the methods.

Conclusions:

• Two distinct imaging and registration workflows provide accurate electrode localization for high-density electrophysiological recordings in rodents.
• Achieved sub-0.1-mm localization accuracy, facilitating reliable multi-session and multi-animal data integration.
• These validated workflows enhance the precision and interpretability of large-scale neural recordings.