TY - JOUR T1 - Long term recordings with immobile silicon probes in the mouse cortex JF - bioRxiv DO - 10.1101/021691 SP - 021691 AU - Michael Okun AU - Matteo Carandini AU - Kenneth D. Harris Y1 - 2015/01/01 UR - http://biorxiv.org/content/early/2015/06/29/021691.abstract N2 - One of the main experimental approaches in systems neuroscience involves extracellular chronic recording of population activity in awake animals, especially behaving rodents. Such chronic recordings were initially performed with single electrodes and tetrodes, and are now increasingly commonly performed with high-density, high-count silicon probes. There is a widespread belief that successful long-term chronic recording requires that one attaches the probes to microdrives that can advance them into the brain and isolate them from mechanical forces. Contrary to these expectations, here we report that it is possible to obtain high quality recordings in both head-fixed and freely moving animals for several months following the implantation of immobile chronic probes. We implanted these probes into the primary visual cortex of mice and obtained highly reproducible responses from well-isolated single units. Although electrode drift could not be completely eliminated, a substantial number of neurons retained their waveform across days. Thus, immobile silicon probes represent a straightforward and reliable technique to obtain stable, long-term population recordings in mice, and follow the activity of multiple isolated neurons over the course of days. ER -