Relationship between electrical potentials of the hippocampus, amygdala, and neocortex during instrumental conditioned reflexes.

Abstract

1. The action of the start-up signal for the conditioned alimentary instrumental reflex results in an increase in the frequency of the theta rhythm to 1.1–2.2 Hz in the hippocampus, an amplification of the theta rhythm in the sensorimotor cortex, and also an amplification of the delta wave in the amygdala, in the frontal cortex, and in the sensorimotor cortex. The alpha, beta 1, and beta 2 frequencies are weakened during this process in all of the structures just referred to. During a period of autostimulation of the emotionally positive zones, the theta rhythm in the hippocampus increases in frequency to 0.7–1.0 Hz; this rhythm is amplified without any change in frequency in the amygdala and sensorimotor cortex. The delta waves were amplified in all of the structures studied; the beta 1 and beta 2 waves were weakened. The alpha waves were amplified only in the hippocampus and in the sensorimotor cortex. 2. The coherence functions reach high values in the delta and theta bands of the biopotentials of the frontal cortex and the hippocampus, the amygdala, and the sensorimotor cortex, but the coherence functions between the biopotentials of the hippocampus and amygdala do not change substantially. 3. Synchronously acting systems are formed in the delta and theta bands of electrical activity during the stage of stabilized motor habits for goal directed behavior; these systems include the frontal cortex-amygdala, the frontal cortex-hippocampus, and the sensorimotor cortex-amygdala systems. In this case, the amygdala and the hippocampus interact with one another only slightly in all of the frequency bands studied; this apparently reflects the different roles of these structures in the organization of behavioral acts.