Subcortical Anatomy of the Default Mode Network: a functional and structural connectivity study

Abstract

Most existing research into the default-mode network (DMN) has taken a corticocentric approach. Despite the resemblance of the DMN with the unitary model of the limbic system, the anatomy and contribution of subcortical structures to the network may be underappreciated due to methods limitation. Here, we propose a new and more comprehensive neuroanatomical model of the DMN including the basal forebrain and anterior and mediodorsal thalamic nuclei and cholinergic nuclei. This has been achieved by considering functional territories during interindividual brain alignment. Additionally, tractography of diffusion-weighted imaging was employed to explore the structural connectivity of the DMN and revealed that the thalamus and basal forebrain had high importance in term of values of node degree and centrality in the network. The contribution of these neurochemically diverse brain nuclei reconciles previous neuroimaging with neuropathological findings in diseased brain and offers the potential for identifying a conserved homologue of the DMN in other mammalian species.

Optogenetic Stimulation of Basal Forebrain Parvalbumin Neurons Activates the Default Mode Network and Associated Behaviors

“…Several studies have provided correlative evidence for an involvement of the BF in DMN-related state transitions. For example, fMRI studies in humans have highlighted robust functional connectivity between BF and cortical areas of the DMN (Alves et al, 2018(Alves et al, , 2019Markello et al, 2018). These findings thus provide structural evidence that is highly consistent with the functional impact of the BF on DMN areas reported in the present study.…”

“…These findings thus provide structural evidence that is highly consistent with the functional impact of the BF on DMN areas reported in the present study. Furthermore, the BF exhibits a particularly high centrality among DMN member structures (Alves et al, 2018(Alves et al, , 2019, potentially consistent with a role of the BF in actively triggering DMN state transitions. Simultaneous recordings from BF and the ACC, an important cortical DMN node, have not only described coherent oscillations among these two areas but also presented evidence for directional coupling from BF to cortex (Nair et al, 2016(Nair et al, , 2018, also suggesting potential involvement of the BF in triggering state transitions.…”

“…Finally, ACC involvement in a rodent DMN has also been shown, both structurally and functionally in mice using fMRI and axonal tracing (Stafford et al, 2014), suggesting that a functional DMN that includes ACC is a general property of the rodent brain. Based on correlative evidence, we therefore hypothesized that the BF may indeed be a subcortical node of the DMN; a notion that is supported by functional imaging studies in macaques and humans (Alves et al, 2018(Alves et al, , 2019Turchi and Sarter, 1997). The BF parvalbumin positive (PV + ) GABAergic corticopetal projection neurons are the most likely candidates for the anatomical substrate of BF participation in DMN regulation.…”

White Matter Changes With Rehabilitation in Children With Developmental Coordination Disorder: A Randomized Controlled Trial

“…Consistent with behavioral evidence of self-regulation mediating CO-OP’s effect (Jokić et al, 2013 ), our results suggest that CO-OP intervention might play a role in self- and attention-regulation. Most of our findings underlie the default mode network (DMN); anterior thalamic radiation, cingulum, corpus callosum, inferior fronto-occipital fasciculus , and white matter tracts to the cuneus and anterior cingulate cortex connect DMN regions in the posterior and anterior cingulate cortices, thalamus, cuneus, as well as across the two hemispheres (Teipel et al, 2010 ; Luo et al, 2012 ; Alves et al, 2019 ). DMN is involved in internally-directed attention, regulating attentional resources, and guiding self-regulatory processes (Bush et al, 2000 ; Grimm et al, 2009 ; Kelly et al, 2009 ; Wiebking et al, 2011 ; Dixon et al, 2014 ).…”

Viewing Ambiguous Social Interactions Increases Functional Connectivity between Frontal and Temporal Nodes of the Social Brain

“…While we cannot speculate what specific role caudate may serve in interpreting social behavior, the area's contribution to social cognition in general is becoming clearer. It has recently been associated with the default mode network ( Alves et al, 2019 ), which itself has been linked to the social brain ( Mars et al, 2012 ). In humans, responses to monetary and social rewards have been associated with striatal activity ( Izuma et al, 2008 ).…”