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Poster Session A: Tuesday, August 12, 1:30 – 4:30 pm, de Brug & E‑Hall

Distinct Microstructural Brain Correlates of Inter-individual Differences in Reward Learning and Decision-Making

Melina Vejlø¹, Niia Nikolova, Leah Banellis, Tobias Hauser, Micah Allen; ¹Aarhus University

Presenter: Melina Vejlø

Humans learn which actions yield the highest rewards through trial and error, forming expectations over time. Yet, people often make suboptimal decisions, partly due to noise in how they learn action values. Such learning processes are implicated in several psychiatric conditions. In a large-scale study, participants completed a gamified reward learning task and surveys measuring impulsivity (using BIS) and compulsivity (using OCI-R). Additionally, they underwent quantitative MRI scanning, in which we measured whole-brain microstructural indices of myelination, myeloarchitecture, and cortical iron. Voxel-based quantification analyses revealed that greater myeloarchitectural integrity, particularly in the left angular gyrus and right postcentral gyrus, correlated with higher learning rates for both chosen and unchosen objects. Learning noise was associated with R1 and R2* values in the precentral gyrus and cerebellum. Impulsivity and compulsivity showed distinct relationships with brain regions, such as the cerebellum, frontal gyrus, and insula. These findings highlight the role of brain microstructure in shaping reward-guided learning and individual differences in impulsivity and compulsivity, with implications for psychiatric disorders.

Topic Area: Reward, Value & Social Decision Making

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