Lasting Behavioral and EEG Changes in Cats Induced by Prolonged Stimulation of Amygdala

Abstract

Social behavior of a colony of eight cats was recorded by time-lapse photography. A picture was taken every 9 seconds for 10 hours daily. Direct observations were also made. Films were analyzed, noting the time spent by each animal in selected patterns of behavior. Permanent cerebral electrodes were implanted in 15 cats and different areas stimulated for half a second every 5 seconds for 1 hour daily for 1–15 days. This type of prolonged stimulation of amygdala increased playful and contactual activities, modified aggressive and sexual behavior and produced other somatic, autonomic and behavioral effects. Local electrical activity was also influenced and seizure-like patterns were persistently recorded. Both behavioral and EEG phenomena were reversible (with 2 exceptions) and reproducible. Similar prolonged stimulation of other cerebral structures (internal capsule, falx cerebri and anterior hypothalamus) did not produce significant results.