Increased intraindividual variability (IIV) is a hallmark of disorders of attention. Recent work has linked these disorders to abnormalities in a "default mode" network, comprising brain regions routinely deactivated during goal-directed cognitive tasks. Findings from a study of the neural basis of attentional lapses suggest that a competitive relationship between the "task-negative" default mode network and regions of a "task-positive" attentional network is a potential locus of dysfunction in individuals with increased IIV. Resting state studies have shown that this competitive relationship is intrinsically represented in the brain, in the form of a negative correlation or antiphase relationship between spontaneous activity occurring in the two networks. We quantified the negative correlation between these two networks in 26 subjects, during active (Eriksen flanker task) and resting state scans. We hypothesized that the strength of the negative correlation is an index of the degree of regulation of activity in the default mode and task-positive networks and would be positively related to consistent behavioral performance. We found that the strength of the correlation between the two networks varies across individuals. These individual differences appear to be behaviorally relevant, as interindividual variation in the strength of the correlation was significantly related to individual differences in response time variability: the stronger the negative correlation (i.e., the closer to 180 degrees antiphase), the less variable the behavioral performance. This relationship was moderately consistent across resting and task conditions, suggesting that the measure indexes moderately stable individual differences in the integrity of functional brain networks. We discuss the implications of these findings for our understanding of the behavioral significance of spontaneous brain activity, in both healthy and clinical populations.
"ed , and social processing ( for a review , see Buckner et al . , 2008 ) . Furthermore , the DMN has been shown to be activated during mind wandering ( Mason et al . , 2007 ; Hasenkamp et al . , 2012 ) . Anti - correlation could be interpreted as a clearer distinction between the networks which might result in better effective connectivity ( Clare Kelly et al . , 2008 ; Deco et al . , 2009 ; Lewis et al . , 2009 ) . Following this line of thought , an increased anti - correlation between insSN and the pvDMN might indicate improved sensitivity to mind wandering in more mindful individuals . This anti - correlation - based connectivity between the insSN and pvDMN was particularly related to the FMI , w"
[Show abstract][Hide abstract] ABSTRACT: Mindfulness is attention to present moment experience without judgment. Mindfulness practice is associated with brain activity in areas overlapping with the default mode, salience, and central executive networks (DMN, SN, CEN). We hypothesized that intrinsic functional connectivity (iFC; i.e., synchronized ongoing activity) across these networks is associated with mindfulness scores. After 2 weeks of daily 20 min attention to breath training, healthy participants were assessed by mindfulness questionnaires and resting-state functional MRI. Independent component analysis (ICA) of imaging data revealed networks of interest, whose activity time series defined inter-network intrinsic functional connectivity (inter-iFC) by temporal correlation. Inter-iFC between subnetworks of the DMN and SN—and inter-iFC between subnetworks of the SN and left CEN at trend—was correlated with mindfulness scores. Additional control analyses about visual networks’ inter-iFC support the specificity of our findings. Results provide evidence that mindfulness is associated with iFC between DMN and SN. Data suggest that ongoing interactions among central intrinsic brain networks link with the ability to attend to current experience without judgment.
Frontiers in Human Neuroscience 08/2015; 9. DOI:10.3389/fnhum.2015.00461 · 2.99 Impact Factor
"Interestingly, the posteriorcortical regions of IIV d -associated decreased volume (including parietal regions; supramarginal gyrus) support research on existing models of neuroanatomical networks in attention and executive functioning (Fernandez-Duque and Posner 2001; Posner and Petersen 1990; Kelly et al. 2008). IIV d is not necessarily related to select anatomical regions of the brain, but may reflect compromised regulation and coordination of functional networks (Kelly et al. 2008). This is important because of the increasing evidence of the progressive breakdown in neuronal networks during the course of progressive neurodegenerative diseases (e.g., Zamrini et al. 2011). "
[Show abstract][Hide abstract] ABSTRACT: To characterize the relationship between dispersion-based intra-individual variability (IIVd) in neuropsychological test performance and brain volume among HIV seropositive and seronegative men and to determine the effects of cardiovascular risk and HIV infection on this relationship. Magnetic Resonance Imaging (MRI) was used to acquire high-resolution neuroanatomic data from 147 men age 50 and over, including 80 HIV seropositive (HIV+) and 67 seronegative controls (HIV-) in this cross-sectional cohort study. Voxel Based Morphometry was used to derive volumetric measurements at the level of the individual voxel. These brain structure maps were analyzed using Statistical Parametric Mapping (SPM2). IIVd was measured by computing intra-individual standard deviations (ISD's) from the standardized performance scores of five neuropsychological tests: Wechsler Memory Scale-III Visual Reproduction I and II, Logical Memory I and II, Wechsler Adult Intelligence Scale-III Letter Number Sequencing. Total gray matter (GM) volume was inversely associated with IIVd. Among all subjects, IIVd -related GM atrophy was observed primarily in: 1) the inferior frontal gyrus bilaterally, the left inferior temporal gyrus extending to the supramarginal gyrus, spanning the lateral sulcus; 2) the right superior parietal lobule and intraparietal sulcus; and, 3) dorsal/ventral regions of the posterior section of the transverse temporal gyrus. HIV status, biological, and cardiovascular disease (CVD) variables were not linked to IIVd -related GM atrophy. IIVd in neuropsychological test performance may be a sensitive marker of cortical integrity in older adults, regardless of HIV infection status or CVD risk factors, and degree of intra-individual variability links with volume loss in specific cortical regions; independent of mean-level performance on neuropsychological tests.
Brain Imaging and Behavior 08/2015; DOI:10.1007/s11682-015-9441-1 · 4.60 Impact Factor
"Also, adults with low performance may not be appropriately representative. Not limited by tasks, resting-state fMRI (R-fMRI) is a powerful tool for mapping maturational changes in brain functional organization (Dosenbach et al., 2010) and indexing inter-individual differences in cognition and behavior (Kelly et al., 2008; Koyama et al., 2011). Most R-fMRI studies of verbal WM have focused on adults (Gordon et al., 2014; Jolles et al., 2013; Takeuchi and Kawashima, 2012). "
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