The hippocampal contribution to verbal fluency in patients with temporal lobe epilepsy

We report the effects of hippocampal and non-hippocampal temporal-lobe dysf unction on verbal fluency performance. Quantitative aspects of semantic and phonemic fluency performance were examined in 46 patients with right- or l eft-temporal-lobe epilepsy and 20 healthy controls. A pattern of fewer word s generated on semantic rather than phonemic fluency tasks was found among patients with damage to hippocampal structures. This pattern was not obtain ed in patients with non-hippocampal temporal-lobe damage, suggesting that t he hippocampus plays a crucial role in semantic fluency performance. An int eresting lateralization effect was obtained. Among patients with left tempo ral-lobe involvement, fluency performance was impaired regardless of whethe r the hippocampus was involved. In contrast, among patients with right temp oral-lobe involvement, fluency performance was impaired only when the hippo campus was involved.