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.

Brain system for mental orientation in space, time, and person

“…The regions we have identified-precuneus and posterior cingulate cortex, IPL, mPFC and lateral temporal and frontal lobes-have been implicated in self-related aspects of space (navigation) (13)(14)(15)(16)(17), time (autobiographical memory) (18)(19)(20)(21), and person (representation of self and others) (22)(23)(24)(25)(27)(28)(29). In addition, these regions are involved in specifying relations between landmarks in each domain: cognitive mapping of the spatial environment, recency judgments of life-events, and social proximity and hierarchy judgments (13,16,(43)(44)(45)(46).…”

Save the Global: Global Signal Connectivity as a Tool for Studying Clinical Populations with Functional Magnetic Resonance Imaging

“…This phenomenon is characterized by widespread fluctuations, predominantly oscillating at frequencies lower than 0.1 Hz, which appear not only during task performance but also during rest (Cordes et al, 2000(Cordes et al, , 2001Lowe et al, 1998). One common method for analyzing resting-state data is termed functional connectivity (FC), and refers to the inspection of temporal correlations between time courses (TCs) of spatially remote brain areas (Biswal et al, 1995;Calhoun et al, 2009;Salomon et al, 2013).…”

“Self pop-out”: agency enhances self-recognition in visual search

“…this illustrates the complexity of self-recognition (sR) which is a fundamental aspect of our self-consciousness (Bermúdez et al 1998). self-representation is construed from integration of multiple afferent sensory signals including visual, tactile, and proprioceptive information (Jeannerod 2003;lenggenhager et al 2007) and has been associated with several brain mechanisms especially in the default mode network (Gusnard et al 2001;salomon et al 2009;salomon et al 2013). While sR is normally effortless robust and does not require attention, it has been shown to be drastically altered by brain pathology (Blanke and Mohr 2005), psychiatric illnesses (Blakemore et al 2000) and experimental manipulations (Blanke and Metzinger 2009;lenggenhager et al 2007;tsakiris et al 2010;salomon et al 2012).…”