To understand computation at the neural-circuit level, we must record action potentials simultaneously and accurately from many hundreds of neurons at distributed brain locations in freely moving animals, at a scale very different from that of contemporary studies.
Conventional tetrode approaches, available in NORBRAIN1, do not allow for such huge cell samples because each wire has only one recording site, at the tip of the electrode. Silicon probes can have many hundred or thousand sites. NORBRAIN shall offer access to a new generation of high-density high-site-count Neuropixels silicon probes, in order to prepare the ground for studies, in Norway and elsewhere, that directly address the population mechanisms of neural coding in brain circuits. During 2 years of technology development and testing (2021-22), we shall set up several rigs for high density silicon-probe recording (basestations, headstages, computer equipment) in rodents.
Neuropixels probes have 384 densely spaced recording sites per electrode shank, with sites in a tetrode configuration. Probes come with 20 um wide shanks, a 15 mm2 head stage of less than 0.5 g, and on-probe electronic signal buffering and switching circuitry.