Cortical microstructural integrity predicts an exploitation bias in older adulthood

Area of Science:

• Neuroscience
• Cognitive Aging
• Decision-Making

Background:

• Prefrontal regions are crucial for explore-exploit decision-making.
• Older adults often exhibit an exploitation bias, coinciding with declining prefrontal myelination.

Purpose of the Study:

• To investigate the link between myelin integrity (MTsat) in prefrontal regions and exploitation bias in older adults.
• To compare the predictive power of microstructural (MTsat) versus macrostructural (cortical thickness) integrity on foraging bias.

Main Methods:

• Quantitative MRI (qMRI) measured magnetization transfer saturation (MTsat) in key brain regions (FPC, OFC, rMFG, dACC, LC).
• 118 cognitively healthy older adults (60-88 years) with familial Alzheimer's disease risk completed a foraging task.
• Associations between MTsat, cortical thickness, and foraging bias were analyzed.

Main Results:

• Lower MTsat in the frontopolar cortex (FPC), medial orbitofrontal cortex (OFC), rostral middle frontal gyrus (rMFG), and locus coeruleus (LC) predicted greater exploitation bias.
• LC and FPC were the strongest predictors; no association was found for the dorsal anterior cingulate cortex (dACC).
• MTsat predicted foraging bias independently of cortical thickness.

Conclusions:

• Individual differences in microstructural integrity within the explore-exploit circuit are linked to exploitation bias in older adults.
• Quantitative MRI (qMRI) markers of microstructural integrity offer valuable insights into age-related decision-making biases.