LARGE-SCALE CORTICAL NETWORKS AND COGNITION

The well-known parcellation of the mammalian cerebral cortex into a la rge number of functionally distinct cytoarchitectonic areas presents a problem for understanding the complex cortical integrative functions that underlie cognition. How do cortical areas having unique individua l functional properties cooperate to accomplish these complex operatio ns? Do neurons distributed throughout the cerebral cortex act together in large-scale functional assemblages? This review examines the subst antial body of evidence supporting the view that complex integrative f unctions are carried out by large-scale networks of cortical areas. Pa thway tracing studies in non-human primates have revealed widely distr ibuted networks of interconnected cortical areas, providing an anatomi cal substrate for large-scale parallel processing of information in th e cerebral cortex. Functional coactivation of multiple cortical areas has been demonstrated by neurophysiological studies in non-human prima tes and several different cognitive functions have been shown to depen d on multiple distributed areas by human neuropsychological studies. E lectrophysiological studies on interareal synchronization have provide d evidence that active neurons in different cortical areas may become not only coactive, but also functionally interdependent. The computati onal advantages of synchronization between cortical areas in large-sca le networks have been elucidated by studies using artificial neural ne twork models. Recent observations of time-varying multi-areal cortical synchronization suggest that the functional topology of a large-scale cortical network is dynamically reorganized during visuomotor behavio r.