Anticipatory Sustained and Action Potentials in Rats.

摘要

In the rat, 'slow' or sustained electrical potentials of cerebral cortex (nonrhythmic potentials enduring longer than a half second) accompany responses to reinforcements of the rewarding type (milk or electrical stimulation of the medial forebrain bundle). The cortex acquires sustained potential gradients of negative polarity as subjects learn to anticipate rewards. Called anticipatory potential gradients or APGs, they develop as a function of fixed time intervals between rewards (temporal conditioning) or in relation to cues of upcoming reward (simple conditioning). The slopes of the gradients decrease when the rats are trained to long (30 second) anticipatory intervals and increase when trained to shorter (10 second) intervals. If we present the rewards at irregular intervals during a session the APGs disappear entirely. The rats require certainty in the timing in order to preserve their cerebral cortical APGs. Restoration of the APGs to pretrial baselines takes the form of a relative positive shift (subsidence of the negative shift) following the rewards. Keywords: DD1473 only; Slow potentials; Sustained potentials; SP; APG; Temporal conditioning; Simple conditioning; Rats; Cerebral cortex; Electrical reward; Self stimulation; Anticipatory potential gradients; Mass unit potentials; Paradoxical decrement. (KT)