Selective neurotoxic amygdala lesions in monkeys disrupt reactivity to food and object stimuli and have limited effects on memory.

Monkeys with bilateral neurotoxic amygdala lesions and normal monkeys were administered tests of emotional reactivity, recognition memory, and reward association memory. There were 3 main findings. First, monkeys with amygdala lesions performed differently than normal monkeys on initial administrations of the emotional reactivity tests and on retests that were given 21-23 months after surgery. Second, they performed like normal monkeys on tests of recognition memory. Third, they were initially impaired on a test of reward association memory, but they were not impaired on a retest that was given 16 months after surgery. These findings underscore the role of the amygdala in aspects of emotional reactivity and reward association memory, but not in recognition memory. In addition, at least some of the behavioral effects of amygdala damage can be long lasting.