COGNITIVE POTENTIALS-IPSILATERAL CORTICOCORTICAL INTERCONNECTIONS IN PREFRONTAL HUMAN CORTEX ABLATIONS

The research deals with the possible role of the essentially monosynap tic bidirectional corticocortical connections between occipito-temporo -parietal association cortical areas and frontal areas in the genesis of some contingent negative variation (CNV) components, especially on the supramodal dorsolateral prefrontal regions. With standard averagin g and topographic mapping methods of analysis, the multicomponent CNV complex formation was examined in 7 patients with extensive frontal co rtex ablations exactly identified through CT/MRT, examinations, and in 10 normal subjects. On the scalp over the ablated frontocortical area s, no consistent post-warning auditory N100 a-b-c, P200, P300, early a nd late CNV components were recordable. The hypothesis is proposed tha t the bidirectional ipsilateral long-distance pathways which interconn ect uni-polymodal occipito-temporo-parietal cortical areas to prefront al ones, in particular the arcuate-superior longitudinal and superior/ inferior occipito-frontal fasciculi, play an important rob in the gene sis of several CNV complex components, especially the multicomponent p ost-Si auditory N100. The posteroanterior sequential latency differenc es of these neurocognitive components, roughly measured along the scal p or on MRT imagings, is probably accounted for by the transcortical i psilateral conduction time of about 1 cm/ms (10 m/s).