MICROELECTRODE STUDIES ON THE EVOKED ACTIVITY OF A SINGLE PYRAMIDAL TRACT CELL IN THE SOMATO-SENSORY AREA IN CATS

Abstract

Orthodromically elicited unitary activity of the pyramidal tract cells which were identified by adequate stimulation of the medullary pyramid of cats were analysed by microelectrode techniques and following results were obtained:
I) A pyramidal tract cell in the pericruciate cortex was fired by single shock stimulation of a peripheral skin nerve.
II) Discharge of the cell could be divided into two types. i.e. an initial spike and late spike discharges.
III) Mode of discharge of the cell was not fixed but a cell with short latency at one time fired at another time with long latency under some experimental situations.
IV) Spike discharges of a pyramidal tract cell appeared coincidentally with negative phases of the surface evoked potential.
V) The shortest connection of a corticospinal fiber from the ventrolateral nuclei of the thalamus to the pyramidal tract cell was monosynaptic in nature.