Instrumental conditioning of sensorimotor cortex EEG spindles in the waking cat

Abstract

The spontaneous occurrence of a 12–20 cps slow-wave spindle recorded from sensorimotor cortex in waking food-deprived cats was systematically reinforced by presentation of milk. This specific EEG pattern was detected by a filter-relay system, the discharge of which was capable of activating the feeding apparatus within an experimental behavior chamber. After several sessions, with 50 reinforcements per session, this sensorimotor rhythm appeared more frequently and demonstrated a regular temporal pattern of occurrence. The consistent behavioral correlate of this EEG response was the assumption of stereotyped postures, characterized by a complete cessation of spontaneous activity. Withholding milk reinforcement resulted in a considerable enhancement of the sensorimotor rhythm during the initial period of extinction. Such changes were not observed, however, when other patterns of sensorimotor cortex electrical activity were reinforced in a similar manner. We conclude that, in the present experiments, it was possible to establish a conditioned sensorimotor cortex slow-wave response of the instrumental type, and that this sensorimotor rhythm has functional significance as a conditioned “central state” related to the inhibition of phasic motor behavior.