Functional Connectivity and Working Memory: An EEG Study

Abstract:
Functional integration of neuronal brain activity (i.e., effective functional connectivity among brain regions) has been proposed as an important neural mechanism involved in the performance of cognitive functions. We assessed cortical effective functional connectivity with EEG coherence measurements that were phase-locked to working memory epochs in a non-spatial visual task. This method enabled us to selectively sample only the working memory component of a multi- determined task without using a subtraction technique. Initial results in a small sample suggested that deficits were associated with reduced EEG coherence between frontal and parietal leads only in the right hemisphere. These findings are consistent with other evidence that working memory is mediated by neural circuitry linking frontal and parietal cortices. Our data suggest that functional integration of these regions (particularly in the right hemisphere) is important for adequate performance on working memory tasks. Results derived from a larger number of subjects will be presented.