Long-term retrograde amnesia ... the crucial role of the hippocampus

For patients with hippocampal pathology, disagreement exists in the literat ure over whether retrograde amnesia is temporally limited or very extensive depending on whether the anatomical damage is restricted to this structure or also involves additional temporal cortex. We report a comprehensive ass essment of retrograde and anterograde memory functions of a severely global amnesic patient (VC). We found that he presented with a remarkably extensi ve and basically ungraded retrograde amnesia. This impairment profoundly af fected four decades preceding the onset of his amnesia and encompassed both non personal and personal facts and events. VC also presented with a sever e anterograde amnesia and a deficit in the acquisition of new semantic know ledge in the post-morbid period. Detailed MRI volumetric measurements revea led gross abnormalities in both hippocampi which were markedly shrunken. Of relevance to the debate on retrograde amnesia were the observations that t he volumes of both entorhinal cortices and the remainder of both temporal l obes were normal. These data suggest that the hippocampus is critical not o nly for the efficient encoding and hence normal recall of new information b ut also for the recall of episodic information acquired before the onset of amnesia. Our results are compatible with the view that retrograde amnesia is both extensive and ungraded when the damage is limited to the hippocampu s. (C) 2000 Elsevier science Ltd. All rights reserved.