Memory impairments following restricted medial thalamic lesions in monkeys.

Thalamic contributions to memory were assessed in monkeys with lesions placed in the medial portions of either the anterior or posterior thalamus (AMT and PMT, respectively). Both lesions produced a moderate impairment in a test of object recognition memory. Furthermore, all three animals in the PMT group and two out of the three in the AMT group were moderately impaired on a test of object-reward associative memory. Comparison of these results with those of a previous study in which the AMT and PMT regions were removed jointly (Aggleton and Mishkin 1983) suggests that damage in either region can induce a memory loss but that combined damage to both is required to produce a full-blown amnesia.