Reusable, flexible, and lightweight chronic implants for Neuropixels probes.

Understanding neural processes such as memory formation, learning, or aging requires tracking the activity of neural populations across short and long time scales. Such longitudinal recordings can be achieved with chronically implanted Neuropixels probes. An ideal chronic implant should (1) allow stable recordings of neurons for weeks; (2) be light enough for use in small animals like mice; (3) allow reuse of the probes after explantation. In this initial preprint, we present the "Apollo Implant", an open-source and editable device that meets all these criteria and accommodates up to two Neuropixels 1.0 or 2.0 probes. The assembled implant comprises two modules: a recoverable "payload" module, and a "docking" module that is cemented to the skull. The design is readily adjustable: the distance between probes, angle of insertion, and depth of penetration can all be easily changed. We tested the implant across multiple labs, and in head-fixed and freely moving animals. The number of neurons recorded across days was stable, even after repeated implantations of the same probe. The Apollo implant thus provides an inexpensive, lightweight, and flexible solution for reusable chronic Neuropixels recordings.