Spatial working memory and intelligence

Previous research utilizing brain imaging techniques has indicated that the prefrontal, parietal and occipital areas all play a role in spatial working memory. Previous psychometric research has indicated a positive relationship between performance on working memory tasks and intelligence. The aim of the present study was to integrate these two lines of research by studying the electrophysiological processes underlying spatial working memory across subjects varying in psychometric intelligence. Steady-state probe topography (SSPT) was used to investigate the cortical activity of 12 average and 12 high IQ volunteers during a spatial working memory task. Holding spatial information in working memory resulted in an increase in the steady-state visual evoked potential (SSVEP) latency in frontal areas, while in parietal and occipital areas there was a decrease in SSVEP latency and an increase in SSVEP amplitude. Increasing the memory load of the working memory task was found to decrease SSVEP latency in the occipital, parietal and right temporal areas and decrease the SSVEP amplitude in the right occipital area. The magnitude of these SSVEP amplitude and latency differences were greater for the high IQ group than for the average IQ group, particularly in posterior areas. These results suggest that the areas of the brain involved in working memory are influenced by individual differences in intelligence.