Memory and the region of the mammillary bodies.

The contribution of the mammillary region to several classes of learning and memory has been reviewed. There is considerable evidence that lesions of this region of the brain impair performance on tasks that require memory for locations that an animal has visited, but that the deficit depends both on the amount of damage within the region and the difficulty of the task. Such lesions, however, do not appear to impair performance on a variety of spatial conditional associative learning tasks which require the animal to form an association between a place or a scene and a stimulus embedded within it. In addition, damage to the region of the mammillary bodies does not impair the ability to learn a variety of non-spatial memory tasks. These studies suggest that the mammillary region may play a selective role in certain types of spatial learning and memory.