Chronic recording of multiple-unit activity from the brain of conscious sheep

A technique is described for recording chronic multiple-unit activity from the brain of conscious sheep. Four to six prefabricated arrays of 6 flexible 70 μm wires were implanted in each of 16 sheep. During implantation the electrode tips were protected with a crystalline glucose sheath, and following implantation the flexible electrode wires allowed the electrode tips to “float” with movements of the brain tissue. The electrodes were connected to a thin recording cable via a “switchboard” mounted on the skull which allowed the experimenter to determine which 4 of the 24–36 electrodes to monitor at any one time.