CORTICAL ACTIVITY OF GOOD AND POOR SPATIAL TEST PERFORMERS DURING SPATIAL AND VERBAL PROCESSING STUDIED WITH SLOW POTENTIAL TOPOGRAPHY

Whether essential processing of spatial information is lateralized asy mmetrically in the human cortex is still a matter of debate. In this s tudy, items of an Item Response Theory calibrated test for spatial abi lity were used to ensure stimulus homogeneity and validity. Subjects w ere preselected as extreme groups of good and poor spatializers. Mappi ng of true DC-recorded slow potential shifts (SPSs) resulted in distin ctly discriminable topographies with spatial and verbal-analytic mater ial as well as with spatial performance groups within the spatial bloc k. Left fronto-central negativity maxima in the verbal condition clear ly contrasted with occipito-parietal peak activity in the spatial cond ition. Poor spatializers showed higher amplitudes as well as a tendenc y to asymmetric activity in right parietal (parieto-temporal) areas, w hereas in good spatializers the activity was localized symmetrically i n occipital and occipito-parietal regions. The findings emphasize the importance of the right posterior cortex for spatial processing (negat ivity maxima at occipital and right parietal sites) and suggest a task -specific lower cortical efficiency or, seen from a processing perspec tive, a higher Investment of Cortical Effort (ICE) on the part of poor spatializers. (C) 1997 Elsevier Science B.V.