Conditioned-reflex analysis of functional connections of the hippocampus and limbic structures.

Abstract

1. An instrumental defensive conditioned reflex formed to stimulation of the dorsal and ventral hippocampus in dogs also was exhibited by generalization in response to stimulation of several limbic structures of the brain. The generalization effect, assessed on the basis of parameters of the conditioned-reflex motor response, depended on the location of the original stimulation of the hippocampus, the location of the testing electrodes, and the degree of consolidation of the original conditioned reflex. 2. Depending on the degree of consolidation of the conditioned reflex the generalization effect underwent two principal types of transformation: from some structures (lateral hypothalamus, lateral septal nucleus, limbic cortex) potentiation of the generalization effect took place with an increase in the number of tests, whereas in other structures (medial nucleus of the amygdala, medial hypothalamus) it was weakened or disappeared completely. 3. Manifestation of the generalization phenomenon from brain structures not originally involved in conditioned-reflex activity is evidence of the existence of close functional connections between these structures and the hippocampus.