Long-term recording of extracellular unitary spikes of the basal ganglia neurons in moving cats.

A technique for long-term recording of unitary spikes of the basal ganglia neurons in moving cats has been introduced. For recording of extracellular unitary spikes teflon-coated platinum/iridium wires of 25 microns diameter (A-M Systems, WA, U.S.A.) are used. A suitable preamplifier using small diodes and FETS is made. A crucial point is to make the head of the preamplifier as small as possible and to connect it to the main part of the preamplifier with soft wires. The same amplitude spikes are picked up by a slicer device and the spikes are converted into square pulses of 1 ms duration. To study the relationship between changes of unitary activities and behavior, a video-tape recording system which includes two cameras, mixing device and editing machine is used. A way of identification of sites of recorded cells is described.