Specialization in the default mode: Task-induced brain deactivations dissociate between visual working memory and attention
Mayer, J. S.1, Roebroeck, A.2, Maurer, K.1, and Linden, D. E. J.3
1Klinik für Psychiatrie, Psychosomatik und Psychotherapie, Goethe-Universität, Frankfurt am Main; 2Faculty of Psychology & Neuroscience, University of Maastricht; 3School of Psychology, University of Wales, Bangor
The default mode hypothesis suggests the existence of an organized mode of brain function that is present as default state and suspended during goal-directed behaviors. We tested this hypothesis by comparing common and selective patterns of fMRI BOLD deactivation in response to the demands on visual attention and working memory (WM). Task-induced deactivations appeared within regions of the default mode network (DMN) with a segregation of areas that were additively deactivated by an increase in the demands on both attention and WM, and areas that were selectively deactivated by either high attentional demand (left lateral temporal and lateral and medial prefrontal cortex) or WM load (right medial-parietal, lateral temporo-parietal, and medial prefrontal cortex). Moreover, during WM encoding deactivated regions showed task-specific functional connectivity. Thus, the DMN can be subdivided into brain regions that deactivate indiscriminately in response to cognitive demand and a part whose deactivation depends on the specific task.