A role of amygdala in visual perception and cognition in macaque monkeys (Macaca fuscata and Macaca mulatta)

To elucidate the role of the amygdala in visual perception and cognition, the effects of ablations of the amygdala and inferotemporal cortex on several visual tasks were compared with each other, and also the distribution patterns of the projections between them were investigated. The findings indicate that the inferotemporal cortex plays a critical role in visual perception, cognition and memory, whereas the amygdala is involved fundamentally in controlling emotional and motivational behavior. However, the amygdala is concerned with vision in the following ways: It receives neutral visual information highly processed in the visual cortex, invests the information with emotional and motivational significance through interactions with the cortical and subcortical systems of emotion and motivation, and then it returns the information coded to the visual areas to be re-processed; to be consciously perceived in area TEO, and to be meaningfully cognized, recognized and memorized in areas TE and TEG. Therefore, two channel model regarding the mechanism of visual information processing in the inferotemporal cortex is proposed: A first channel is concerned with processing neutral information, while the second one, with processing meaning information coded emotionally and motivationally in the amygdala. In addition, the present studies demonstrate that area TEG, which is cytoarchitecturally a transitional area between areas TE and TG and whose functional significance has remained unclear, is involved significantly in visual cognition rather than visual perception.