title: Deconstructing the default: cortical subdivision of the default mode/intrinsic system during self-related processing.
abstract: Recent brain imaging research has highlighted a new global system of areas termed the Default Mode network (DM), which appears to specialize in intrinsically oriented functions. However, it is still unresolved to what extent this system contains functional subsystems as in the better known sensory and motor cortices. Here, we report that functional subdivisions can be revealed within individual nodes of the DM, such as the Inferior Parietal Lobule (IPL), through the use of different categories of self-oriented tasks. Subjects underwent BOLD fMRI scans during which they were asked to recall self-related positive and negative information in the categories of people and food. These tasks elicited distinct regions of activation within the DM. Importantly, the observed activations were above the activity level in the baseline, no-task condition for these regions. The main subdivision within the DM was observed in the inferior and posterior parietal cortex. Analysis of coherent resting state fluctuations (functional connectivity analysis) revealed that these regions of activation were part of a distinct network of regions within the DM. These results argue against viewing the DM as a unitary system, and are compatible with the notion that, similar to the rest of the cerebral cortex, the DM consists of distinct, functionally specialized subregions.
authors.affiliation: Department of Psychology, Tel Aviv University, Ramat Aviv 69978, Israel; Laboratory of Cognitive Neuroscience, Deptartment of Life Sciences, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Roy
authors.initials: R
authors.lastname: Salomon
authors.forename: Dana Rubi
authors.initials: DR
authors.lastname: Levy
authors.forename: Rafael
authors.initials: R
authors.lastname: Malach
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D012146:Rest / Q000502:physiology; D012649:Self Concept; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: cortical specialization; fMRI; functional connectivity; rest; self-referential processing