THE CONTRIBUTION OF THE ANTERIOR THALAMIC NUCLEI TO ANTEROGRADE AMNESIA

This paper first reviews the anatomical, pathological, and neuropsycho logical evidence implicating the anterior thalamic nuclei in memory pr ocesses. It is concluded that there is much indirect evidence indicati ng that anterior thalamic dysfunction is an important factor in antero grade amnesia. More direct evidence for the involvement of the anterio r thalamic nuclei in memory processes emerges from two experiments wit h rats that examined performance of a spatial test of working memory, delayed nonmatching-to-position. The first study revealed that neuroto xic lesions of the anterior thalamic nuclei and radiofrequency lesions of the fornix both produce equivalent performance deficits. In contra st, lesions of the mamillary bodies were without effect. A second stud y showed that lesions of the fornix and removal of the hippocampus pro duced very similar deficits. These data indicate that while the involv ement of the anterior thalamic nuclei in certain memory functions depe nds on inputs from the hippocampus, this involvement need not depend o n indirect afferents via the mamillary bodies.