Mild topographical memory impairment following crossed unilateral lesions of the mediodorsal thalamic nucleus and the inferotemporal cortex.

Monkeys with crossed unilateral lesions of the dorsomedial thalamus and contralateral ablations of the inferotemporal cortex were mildly impaired on acquisition and retention of visual conditional tasks requiring the integration of information about objects and their positions in space. They were not impaired on other conditional and nonconditional tasks. This impairment pattern resembles, qualitatively, that found following crossed unilateral lesions of the anterior thalamus and the inferotemporal cortex or bilateral lesions of the anterior and mediodorsal thalamic nuclei. Although the flow of visual information from the inferotemporal cortex through the hippocampal-fornix-anterior thalamic circuit plays a major part in memory for objects in places, the flow of information between inferotemporal cortex and mediodorsal thalamus, possibly by means of the frontal cortex, also makes some contribution.