Involvement of both prefrontal and inferior parietal cortex in dual-task performance

This PET study explored the neural substrate of bot h dual-task management and integration task using s ingle tasks that are known not to evoke any prefrontal ac tivation. The paradigm included two simple (visual and auditory) discrimination tasks, a dual task and an integration task (requiring simultaneous visual and auditory discrimination), and baseline tasks (passive viewin g and hearing). Data were analyzed using SPM99. As predicted, the comparison of each single task to th e baseline task showed no activity in prefrontal ar eas. The comparison of the dual task to the single tasks dem onstrated left-sided foci of activity in the fronta l gyrus (BA 9/46, BA 10/47 and BA 6), inferior parietal gyrus ( BA 40), and cerebellum. By reference to previous neuroimaging studies, BA 9/46 was associated with t he coordinated manipulation of simultaneously prese nted information, BA 10/47 with selection processes, BA 6 with articulatory rehearsal, and BA 40 with atten tional shifting. Globally similar regions were found for t he integration task, except that the inferior parie tal gyrus was not recruited. These results confirm the hypothesis that the left prefrontal cortex is implicated in d ual-task performance. Moreover, the involvement of a parieta l area in the dual task is in keeping with the hypo thesis that a parieto-frontal network sustains executive functi oning. Theme: Neural basis of behavior