Atypical language representation in epilepsy: implications for injury-induced reorganization of brain function.

This review addresses language function and reorganization associated with various forms of epilepsy. Longstanding epilepsy, particularly types with onset early in life, may be associated with changes in the representation of language function in the brain. As a result of this reorganization, language function may be relatively spared despite injury to areas of the brain that normally subserve these functions. We examine the changes seen in language function in two types of epilepsy: hemispheric epilepsy of childhood and focal epilepsies. Findings from behavioral studies, intracarotid amytal testing, intraoperative cortical testing, and more recent functional imaging studies are reviewed. Studying changes in the representation of language function seen in some forms of epilepsy provides information about brain plasticity with implications for other neurologic diseases, as well as for the neuroscientific understanding of how and when functional reorganization may occur.

Late frontal brain potentials distinguish true and false recognition.

Brain potentials associated with true and false recognition were recorded using a paradigm consisting of categorized color photographs. Two ERP components were identified. A parietal component was most positive for both true and false recognition, less positive for rejection of lures, and least positive for rejection of novel items. A later frontal component was more positive for false recognition, rejection of lures, and misses than for true recognition and rejection of novel items. The authors suggest that the parietal component may reflect the extent to which test items engender recollection of the gist representation of the study list, while the late frontal component may reflect the engagement of effortful post-retrieval processes.