Summary: A new study identified the right inferior frontal gyrus (rIFG) as a central regulator in the brain’s inhibitory control circuit.
Using dynamic causal modeling and fMRI on a sample of 250 participants, the study reveals that the rIFG significantly influences the caudate nucleus and thalamus during response inhibition tasks. This research also shows gender differences in brain function: women have distinct neural patterns in the thalamus, and overall, better inhibitory control correlates with stronger neural communication from the thalamus to the rIFG.
These findings provide valuable insights for developing neuromodulation therapies for mental and neurological disorders with inhibitory control deficits.
The study identifies the right inferior frontal gyrus (rIFG) as a crucial component in controlling the brain’s response inhibition.
Gender-specific brain functioning was observed, with women showing different neural activity patterns in the thalamus compared to men.
Stronger neural communication from the thalamus to the rIFG was linked to better inhibitory control, highlighting potential targets for neuromodulation therapies.
Source: West China Hospital of Sichuan University
Published in the 2023 Volume 3 issue of Psychoradiology a team of dedicated researchers from The University of Hong Kong and The University of Electronic Science and Technology of China has conclusively identified the right inferior frontal gyrus (rIFG) as a key input and causal regulator within the subcortical response inhibition nodes.
This right-lateralized inhibitory control circuit, characterized by its significant intrinsic connectivity, highlights the crucial role of the rIFG in orchestrating top-down cortical-subcortical control, underscoring the intricate dynamics of brain function in response inhibition.
In this comprehensive study, researchers employed dynamic causal modeling (DCM-PEB) and functional magnetic resonance imaging (fMRI) with a substantial sample size (n = 250) to explore inhibitory circuits in the brain, particularly focusing on the right inferior frontal gyrus (rIFG), caudate nucleus (rCau), globus pallidum (rGP), and thalamus (rThal).
This approach treated the brain as a nonlinear dynamical system, enabling the estimation of directed causal influences among these nodes, influenced by task demands and biological variables.
Findings revealed a high intrinsic connectivity within this neural circuit, with response inhibition notably enhancing causal projections from the rIFG to both rCau and rThal, particularly amplifying the regulatory role of the rIFG during such tasks.
The study also uncovered that sex and performance metrics significantly affect the circuit’s functional architecture; for instance, women exhibited increased self-inhibition in the rThal and reduced modulation to the GP, while better inhibitory performance was linked to more robust communication from the rThal to the rIFG.
Interestingly, these communication patterns were not mirrored in a left-lateralized model, highlighting a hemispheric asymmetry.
The research indicates that different brain processes might mediate similar behavioral performances in response inhibition across genders, particularly in thalamic loops, with higher response inhibition accuracy associated with stronger information flow from the rThal to the rIFG.
These insights into the brain’s inhibitory control mechanisms have significant implications for understanding a range of mental and neurological disorders characterized by response inhibition deficits.
The study’s findings could guide the development of targeted neuromodulation strategies and personalized interventions to address these deficits, enhancing the treatment and management of such conditions.
The National Key Research and Development Program of China (2018YFA0701400), The National Natural Science Foundation of China (31530032, 91632117, 32200904), The Key Technological Projects of Guangdong Province (2018B030335001).
The right inferior frontal gyrus as pivotal node and effective regulator of the basal ganglia-thalamocortical response inhibition circuit
The involvement of specific basal ganglia-thalamocortical circuits in response inhibition has been extensively mapped in animal models. However, the pivotal nodes and directed causal regulation within this inhibitory circuit in humans remains controversial.
The main aim of the present study was to determine the causal information flow and critical nodes in the basal ganglia-thalamocortical inhibitory circuits and also to examine whether these are modulated by biological factors (i.e. sex) and behavioral performance.
Here, we capitalize on the recent progress in robust and biologically plausible directed causal modeling (DCM-PEB) and a large response inhibition dataset (n = 250) acquired with concomitant functional magnetic resonance imaging to determine key nodes, their causal regulation and modulation via biological variables (sex) and inhibitory performance in the inhibitory circuit encompassing the right inferior frontal gyrus (rIFG), caudate nucleus (rCau), globus pallidum (rGP), and thalamus (rThal).
The entire neural circuit exhibited high intrinsic connectivity and response inhibition critically increased causal projections from the rIFG to both rCau and rThal. Direct comparison further demonstrated that response inhibition induced an increasing rIFG inflow and increased the causal regulation of this region over the rCau and rThal. In addition, sex and performance influenced the functional architecture of the regulatory circuits such that women displayed increased rThal self-inhibition and decreased rThal to GP modulation, while better inhibitory performance was associated with stronger rThal to rIFG communication. Furthermore, control analyses did not reveal a similar key communication in a left lateralized model.
Together, these findings indicate a pivotal role of the rIFG as input and causal regulator of subcortical response inhibition nodes.