The TD drive - A parametric, open-source implant for multi-area electrophysiological recordings in behaving and sleeping rats

Intricate interactions between multiple brain areas underlie most functions attributed to the brain. The process of learning, as well as formation and consolidation of memories are two examples that rely heavily on functional connectivity across the brain. In addition, investigating hemispheric similarities and/or differences goes hand in hand with these multi-area interactions. Electrophysiological studies trying to further elucidate these complex processes thus depend on recording brain activity at multiple locations simultaneously and often in a bilateral fashion. Presented here is a 3D-printable implant for rats, named TD drive, capable of symmetric, bilateral wire electrode recordings, currently in up to ten distributed brain areas simultaneously. The open-source design was created employing parametric design principles, allowing prospective users to easily adapt the drive design to their needs by simply adjusting high-level parameters, such as anterior-posterior and medio-lateral coordinates of the recording electrode locations. The implant design was validated in n = 20 Lister Hooded rats that performed different tasks. The implant was compatible with tethered sleep recordings and open field recordings (Object Exploration) as well as wireless recording in a large maze (HexMaze 9×5 m) using two different commercial recording systems and headstages.

In sum, presented here is the adaptable design and assembly of a new electrophysiological implant facilitating fast preparation and implantation.