The Japanese journal of neuropsychology

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ArticleTitle	Controversies on the roles of medial temporal lobe for memory consolidation
Language	J
AuthorList	Toshikatsu Fujii
Affiliation	Division of Neuropsychology, Department of Disability Medicine, Tohoku University Graduate School of Medicine
Publication	Japanese Journal of Neuropsychology: 16 (3), 164-170, 2000
Received
Accepted
Abstract	Memory consolidation refers to the idea that neurophysiological processes occurring after the initial registration of information contribute to the permanent storage of memory. This idea has been supported by the phenomenon of temporally graded (or temporally limited) retrograde amnesia after brain injury. However, the precise roles of medial temporal structures, as well as other memory-related structures, for memory consolidation remain unclear so far. In this article, data on retrograde amnesia after damage mainly to medial temporal lobe were reviewed in terms of lesion profile and the nature/extent of retrograde amnesia. From the data, the following points regarding retrograde amnesia after temporal lobe damage emerged. The bilateral lesions to the medial temporal lobes that include other regions in addition to the hippocampus proper produce extensive retrograde amnesia, the severity and length of which increases as more regions are implicated, often leading to a retrograde amnesia that covers and individual's entire life. Retrograde amnesia is most severe for autobiographical episodes, but is also substantial for knowledge of public figures and events. When damage is limited to the hippocampus proper, the period of retrograde amnesia is very short, though it may be shown to extend further if more sensitive tests were used. Finally, in light of the data reviewed, the author evaluated two different models of memory consolidation, the traditional consolidation model and the multiple trace theory.
Keywords	Medial temporal lobe, Hippocampus, Retrograde amnesia, Memory consolidation