Unit-activity in the central amygdalar nucleus of rats in response to immobilization--stress

Multiple-unit activity in the central nucleus of the amygdala of rats was measured during immobilization and during presentations of a white-noise stimulus that had been paired with the restraint treatment. Results showed that some units responded with an increase, others with a decrease in firing rate during immobilization. Several units also showed "conditioned" rate changes to the auditory stimulus. A behavioral assessment of the presumed conditioned aversive properties of the stimulus showed that the rats which had experienced the pairing of restraint and the noise stimulus escaped faster when presented with the stimulus than the unpaired controls. It is suggested that the central amygdala might be part of a system in which stressful inputs influence autonomic functions.