Method for acute Neuropixels probe recordings in non-human primates

Abstract

Neuropixels (NP) probes are a significant advance in electrophysiological recording technology that enable monitoring of hundreds of neurons in the brain simultaneously across depth. Application of this technology has been predominately in rodents, however, and widespread use in larger non-human primates (NHPs) such as rhesus macaques has been limited. There are two overarching challenges that impede acute NP implantation in NHPs: (1) traditional microdrive systems that mount to cephalic chambers that are commonly used to access cortical areas for microelectrode recordings are not designed to accommodate NP probes, and (2) NHPs have thick dura mater and tissue growth within the cephalic chambers which poses a challenge for insertion of the extremely fragile NP probe. In this study we present a novel Neuropixels guide tube system that can be adapted to commercial microdrive systems and was developed using a combination of CAD design, 3D printing, and small part machining. Software programs, 3D Slicer and SolidWorks were used to target cortical areas, approximate recording depths and locations, and for in-silico implant testing. Finally, we performed in vivo testing to validate our methodology, successfully implanting and reimplanting NP probes and collecting stable neurophysiological recordings in premotor cortex of a rhesus macaque at rest and during performance of a behavioral reaching task. Once data were collected, we proceeded to evaluate neuronal responses across the NP probe shank to characterize changes in information processing across cortical depth during reach initiation.