The structural basis of semantic control: Evidence from individual differences in cortical thickness

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Neuroanatomy

Background:

• Semantic control enables flexible conceptual retrieval, engaging networks like the left inferior prefrontal gyrus (IFG) and posterior middle temporal gyrus (pMTG).
• The neural basis of individual differences in semantic control capacity remains largely unknown, as task-activated regions may not correlate with performance variations.

Purpose of the Study:

• To identify structural markers associated with individual differences in semantic control.
• To investigate the relationship between brain structure, functional connectivity, and controlled semantic retrieval performance.

Main Methods:

• Combined MRI-based cortical thickness analysis with resting-state fMRI connectivity.
• Assessed individual differences in controlled semantic retrieval performance.
• Examined structural covariance patterns between brain regions.

Main Results:

• Higher performance in controlled semantic retrieval was associated with increased structural covariance between the left posterior middle temporal gyrus (pMTG) and left anterior middle frontal gyrus (aMFG).
• This structural covariance pattern was specific to semantic control and did not predict performance on non-semantic judgments.
• The intrinsic functional connectivity of the pMTG-aMFG network overlapped with known semantic control regions, including bilateral IFG and intraparietal sulcus.

Conclusions:

• Semantic control performance is predicted by a structural covariance network involving the left pMTG, highlighting its role beyond consistently activated regions like the left IFG.
• Findings suggest semantic control is partially separable from domain-general executive control.
• Flexible memory retrieval is associated with the co-variation of pMTG with distant prefrontal regions (aMFG), supporting a distributed network for semantic control.