Preferential impairment of avoidance performances in amygdala-lesioned mice.

To clarify the role of the amygdala in the fulfillment of memory and/or learning, amygdala-lesioned mice were tested in passive and active avoidance performances and also in spatial learning tasks. Although the lesioned animals showed deteriorated performances in both passive and active avoidance tests, they executed the spatial learning tasks as well as the control mice. The learning deficit was prominent in the process of memory acquisition of passive and active avoidance tasks, suggesting that the amygdala might be involved in the acquisition processes of these avoidance tests. The locomotor activities of the lesioned animals were slightly increased, but there was no significant difference compared with the control mice. These findings indicate that the amygdala plays a crucial role preferentially in the avoidance learning rather than the spatial learning.