Rabbit and monkey visual cortex: more than a year of recording with up to 64 microelectrodes

In the visual cortex of rabbits and a marmoset monkey, 32 and 64 microwires , respectively, were chronically implanted by an indirect insertion method so that the cortex was penetrated from the white matter. For more than 1 ye ar recordings of action potentials of good quality were obtained at most el ectrodes. Recording stability was judged by spike shape, spike train autoco rrelograms, and spike rates: within recording sessions, stability was essen tially perfect. Periods in which the signals of several electrodes were sta ble could last for several days. A method of in vivo reconstruction of the electrode locations by micro-X-rays and subsequent stereophotogrammetry is presented. The aspect of animal welfare is considered. (C) 2000 Elsevier Sc ience B.V. All rights reserved.