An approach for long-term, multi-probe Neuropixels recordings in unrestrained rats

The use of Neuropixels probes for chronic neural recordings is not yet widespread, and initial studies leave questions about long-term stability and probe reusability unaddressed. Here, we demonstrate a new approach for chronic Neuropixels recordings over a period of months in freely moving rats. Our approach allows multiple probes per rat and multiple cycles of probe reuse. We found that hundreds of units could be recorded for multiple months, but that yields depended systematically on anatomical position. Explanted probes displayed a small increase in noise compared to unimplanted probes, but this was insufficient to impair future single-unit recordings. We conclude that cost-effective, multi-region, and multi-probe Neuropixels recordings can be carried out with high yields over multiple months in rats or other similarly sized animals. Our methods and observations may facilitate the standardization of chronic recording from Neuropixels probes in freely moving animals.
, Subjects
A total of 18 male Long-Evans rats (Rattus norvegicus) were used in this study. Four of them were BAC transgenic rats expressing Cre recombinase. These rats were used for the purpose of targeting optogenetic constructs to cell types of interest for experiments not described in the present report. These rats came from the following three lines: LE-Tg(Pvalb-iCre)2Ottc (n=1), LE-Tg(Gad1-iCre)3Ottc (n=2), LE-Tg(Drd2-iCre)1Ottc (n=1). These lines were made by the Transgenic Rat Project at the National Institute of Drug Abuse (NIDA) and were obtained from the Rat Resource and Research Center (RRRC) at the University of Missouri.  All rats were water restricted to motivate them to work for water as reward, and obtained a minimum volume of water per day equal to 3% of their body mass. If rats consumed less than this minimum during performance of the task, additional water was offered after training. Rats were kept on a reversed 12-hr light-dark cycle and were trained in their dark..., , # Data from: An approach for long-term, multi-probe Neuropixels recordings in unrestrained rats

[https://doi.org/10.5061/dryad.m63xsj3zw](https://doi.org/10.5061/dryad.m63xsj3zw)

## Description of the data and file structure

All data are stored in MATLAB (.mat) files within the data.zip. There are 135 files in total, each corresponding to a single recording session and named as “subjectID_YYYY_MM_DD_<notes>.mat,” based on the subject ID and the recording date.

Location of each unit

* *brainregion*: brain region of each unit
* *hemisphere*: 'left' or 'right'
* *AP*: Anterior-posterior distance of each unit relative to the bregma skull landmark, in millimeters
* *ML*: medial-lateral distance, similar to above
* *DV*: dorsal-ventral distance, similar to above
* *bank*: The recording electrodes of Neuropixels 1.0 probes are organized into different banks, and this indicates the bank of each unit.
* *electrode*: Neuropixels 1.0 recording site of each unit
* *dist_from_tip_um :* distance...,