THE CONTRIBUTION OF THE ANTERIOR THALAMIC NUCLEI TO ANTEROGRADE AMNESIA

This paper first reviews the anatomical, pathological, and neuropsychological evidence implicating the anterior thalamic nuclei in memory processes. It is concluded that there is much indirect evidence indicating that anterior thalamic dysfunction is an important factor in anterograde amnesia. More direct evidence for the involvement of the anterior thalamic nuclei in memory processes emerges from two experiments with rats that examined performance of a spatial test of working memory, delayed nonmatching-to-position. The first study revealed that neurotoxic lesions of the anterior thalamic nuclei and radiofrequency lesions of the fornix both produce equivalent performance deficits. In contrast, lesions of the mamillary bodies were without effect. A second study showed that lesions of the fornix and removal of the hippocampus produced very similar deficits. These data indicate that while the involvement of the anterior thalamic nuclei in certain memory functions depends on inputs from the hippocampus, this involvement need not depend on indirect afferents via the mamillary bodies.