Electrophysiological activity in the central nucleus of the amygdala: emotionality and stress ulcers in rats

Multiple-unit activity in the central nucleus of the amygdala was continuously recorded during 4 hr of restraint stress in rats. Five different activity profiles were found. Two types were associated with stress ulceration: one with increased stomach pathology, and the other with decreased stomach pathology. The same unit profiles were also differentially related to the emotionality characteristics of Wistar-derived rats, as well as to those of the genetically selected lines of Roman high- and low-avoidance rats. The type of profile that had been associated with increased pathology was generally seen in the Roman low-avoidance rats and in the Wistar rats that had been judged to be more emotional, that is, defecated before five "rearings" had occurred in an open-field test. The other unit profile was significantly more frequent in the Roman high-avoidance animals and the less emotional Wistar rats. Low-level electrical stimulation of both types of units produced stomach erosions in all cases. It was concluded that the unit activity in the central nucleus of the amygdala reflects certain emotionality characteristics of rats and also their susceptibility of stress ulcers.