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Subcortical brain circuits reflect changing motivational demands at different time scales during effort-based decision-making

Poster Session E - Monday, March 9, 2026, 2:30 – 4:30 pm PDT, Fairview/Kitsilano Ballroom

Rong Bi¹, Lilian Weber², Jan Grohn¹, Miriam Klein-Flügge¹; ¹University of Oxford, ²Osnabrück University

Humans show remarkable flexibility in adapting their motivation to constantly changing environments. Prior work looking at motivated behaviour has largely focused on tasks where effort requirements are directly instructed. However, in everyday life, motivational requirements are not precisely signalled by the environment. In the current study, we used ultra-high-field MRI to examine how small subcortical nuclei of the human brain support effort learning and decision-making when effort is not signalled. Participants were asked to make decisions between two options with varying reward points and required effort, in environments with overall low versus high effort requirements. High average effort increased effort sensitivity and encouraged choice switches. A prediction error-based learning model was able to capture the influence of average effort demands on estimated effort updating across trials and effort devaluated reward differently in high compared to low effort contexts. 7T-fMRI BOLD showed that posterior hypothalamus reflected average effort demands, central/cortical amygdala reflected the effort required to persist, and nucleus accumbens represented rewards differentially in high and low effort environments. Finally, functional connectivity in this network changed as a function of effort changes. In summary, when effort is not instructed, subcortical circuits support flexible regulation of motivational demands at different timescales. Key words: motivation, effort, volatility, average effort, learning, uncertainty, nucleus accumbens, amygdala, hypothalamus, subcortical region, flexibility

Topic Area: THINKING: Decision making