Brain activity at rest: a multiscale hierarchical functional organization

Abstract

Spontaneous brain activity was mapped with functional MRI (fMRI) in a sample of 180 subjects while in a conscious resting-state condition. With the use of independent component analysis (ICA) of each individual fMRI signal and classification of the ICA-defined components across subjects, a set of 23 resting-state networks (RNs) was identified. Functional connectivity between each pair of RNs was assessed using temporal correlation analyses in the 0.01-to 0.1-Hz frequency band, and the corresponding set of correlation coefficients was used to obtain a hierarchical clustering of the 23 RNs. At the highest hierarchical level, we found two anticorrelated systems in charge of intrinsic and extrinsic processing, respectively. At a lower level, the intrinsic system appears to be partitioned in three modules that subserve generation of spontaneous thoughts (M1a; default mode), inner maintenance and manipulation of information (M1b), and cognitive control and switching activity (M1c), respectively. The extrinsic system was found to be made of two distinct modules: one including primary somatosensory and auditory areas and the dorsal attentional network (M2a) and the other encompassing the visual areas (M2b). Functional connectivity analyses revealed that M1b played a central role in the functioning of the intrinsic system, whereas M1c seems to mediate exchange of information between the intrinsic and extrinsic systems.

Connectomics and Neuroticism: An Altered Functional Network Organization

“…Specifically, we found that the functional network structure of individuals with higher levels of neuroticism is organized less optimally in terms of efficient information processing and consists of weaker functional connections. Furthermore, in high compared with low neurotic individuals, we showed that subnetworks related to emotion and salience processing have a more prominent role in the network organization, while subnetworks related to sensory(-motor) functions and cognitive control have a less prominent role (Doucet et al, 2011;Kinnison et al, 2012;Laird et al, 2011). This is in line with previous studies demonstrating that individuals with higher levels of neuroticism show more difficulties in adaptive emotion regulation (Suls and Martin, 2005;Watson and Hubbard, 1996;Yoon et al, 2013).…”

“…for emotional instability: subnetworks related to emotion and salience processing have a more prominent role in the functional network organization of individuals scoring higher on neuroticism, while subnetworks that potentially control and regulate responses from these subnetworks have a less prominent role (Doucet et al, 2011;Kinnison et al, 2012;Laird et al, 2011). This is in line with evidence showing that high compared with low neurotic individuals experience more intense negative emotions, such as feelings of depression and anxiety, and demonstrate heighted emotional reactivity to negative events (Suls and Martin, 2005;Watson et al, 1994).…”

Brain activity and connectivity during poetry composition: Toward a multidimensional model of the creative process

“…A novel method of functional network connectivity (FNC) analysis has previously been applied to resting‐state data [Allen et al, 2011; Doucet et al, 2011; Jafri et al, 2008]. Here, this FNC method was used in a task‐based study.…”

“…The time courses of remaining 53 components for each subject and condition, which were computed from the group ICA time courses by a PCA‐based back‐reconstruction method [Erhardt et al, 2011], were used for the following FNC analyses [Allen et al, 2011; Doucet et al, 2011; Jafri et al, 2008]. …”

“…The correlation matrix, R , was converted to a distance or linkage matrix, D  = 1− R , indicating dissimilarity between each component pair. Agglomerative hierarchical clustering on these distance values was done to sort the components in a data‐driven fashion, so that those with similar temporal dynamics were placed together in a cluster [Doucet et al, 2011]. The distance between two clusters was the average distance between all pairs of their elements.…”