An early electrophysiological sign of semantic processing in basal extrastriate areas

Recognition potential (RP), a recently discovered electrophysiological resp onse of the brain, is sensitive to semantic aspects of stimuli. Given its p eak values (about 250 ms), RP may be a good candidate for the study of sema ntic processing during its occurrence. However, its topography and neural g enerators are largely unknown. To improve this state of affairs, high-resol ution electmencephalography and brain electrical source analysis were carri ed out. Results suggest a possible origin of RP in the lingual gyrus, hence reflecting the activity of the basal extrastriate areas. RP therefore appe ars to be a highly valuable tool in the study of those regions considered t o be the "third language areas" tin addition to Broca's and Wernicke's area s, whose precise role in language processing is still largely unknown. Anot her important finding was that RP amplitude in the left hemisphere differed as a function of the semantic category of the stimuli, providing evidence for the sensitivity of this component to semantic categorization, A tentati ve proposal is made with regard to the role of the basal extrastriate areas .