Anatomical substrates of interictal memory deficits in temporal lobe epileptics

Temporal lobe epileptics frequently have as their pathological substrate selective neuron loss of the hippocampus. The extent and pattern of the hippocampal cell loss vary among patients. These patients also exhibit varying degrees of memory loss. We have demonstrated a relationship between the memory loss in left temporal lobe epileptics and their hippocampal lesions. Specifically, we have identified a memory measure, delayed-recall of unrelated word-pairs, that is highly dependent upon integrity of left hippocampus. We have also shown that extensive damage throughout the hippocampus is necessary to consistently impair this measure. These findings are relevant to understanding the memory loss of temporal lobe epileptics as well as providing insight into our understanding of the anatomical basis of memory.