Cortical and subcortical contributions to non-motor inhibitory control: an fMRI study

Abstract

Inhibition is a core executive cognitive function. However, the neural correlates of non-motor inhibitory control are not well understood. We investigated this question using functional Magnetic Resonance Imaging (fMRI) and a simple Count Go/NoGo task (n = 23), and further explored the causal relationships between activated brain regions. We found that the Count NoGo task activated a distinct pattern in the subcortical basal ganglia, including bilateral ventral anterior/lateral nucleus of thalamus (VA/VL), globus pallidus/putamen (GP/putamen), and subthalamic nucleus (STN). Stepwise regressions and mediation analyses revealed that activations in these region(s) were modulated differently by only 3 cortical regions i.e. the right inferior frontal gyrus/insula (rIFG/insula), along with left IFG/insula, and anterior cingulate cortex/supplementary motor area (ACC/SMA). The activations of bilateral VA/VL were modulated by both rSTN and rIFG/insula (with rGP/putamen as a mediator) independently, and the activation of rGP/putamen was modulated by ACC/SMA, with rIFG/insula as a mediator. Our findings provide the neural correlates of inhibitory control of counting and causal relationships between them, and strongly suggest that both indirect and hyperdirect pathways of the basal ganglia are involved in the Count NoGo condition.

Differential Cortical and Subcortical Activations during Different Stages of Muscle Control: A Functional Magnetic Resonance Imaging Study

“…During the relaxation stage, participants were instructed to simply relax their muscles. Activation in the STN was observed in this process, consistent with a non-motor Count NoGo task with nearly identical coordinates [28]. This finding aligns with the basal ganglia model, where the STN is part of the indirect pathway as well as the hyperdirect pathway for inhibiting a behavior [23,24,31,32,34].…”

“…There is also a third hyperdirect pathway involving neurons that travel directly from the cerebral cortex to the STN, bypassing the striatum. This pathway has a shorter conduction time than effects conveyed through the striatum, and therefore provides rapid inhibition for action suppression [24] and non-motor suppression [28]. It is expected that this pathway would be less engaged in the natural relaxation of muscles in this study.…”

“…During the relaxation stage, only activation of the putamen, rather than the caudate, was observed, indicating that the putamen plays a crucial role in muscle relaxation or the deactivation of alpha motor neurons. Indeed, previous studies have consistently implicated the putamen in inhibition tasks such as motor NoGo tasks [50,51] and a non-motor counting NoGo task [28].…”

“…Moreover, the specific roles of the two subregions of the striatum (i.e., caudate and putamen) in voluntary motor control are not fully understood, but may exhibit differences. For example, activation in the putamen, as opposed to the caudate, has been associated with successful inhibition [31][32][33][34], including inhibiting counting [28]. Note that in patients with Parkinson's disease, the loss of dopamine occurs predominantly in the posterior putamen [35].…”