The neural basis of habit formation measured in goal-directed response switching

TL;DR

This study explores how the brain switches from habitual actions to goal-directed behaviors, identifying key brain regions and mechanisms involved in habit formation and control.

Contribution

The study identifies specific cortical-striatal networks and the causal role of the premotor cortex in habit control using fMRI and TMS.

Findings

Overtraining increases RT switch costs, indicating stronger habitual behavior.

fMRI shows distinct brain regions for habit expression and overriding.

TMS of the left premotor cortex enhances habit control performance.

Abstract

Replacing a habitual action with goal-directed control involves a cost whose neural mechanisms in humans are not well established. Our study quantifies this cost and uncovers its neural correlates using fMRI and neurostimulation. Training S-R links in overtrained stimuli (compared to less trained ones, termed standard-trained stimuli) increased RT switch costs, explained by drift diffusion modeling. Training engaged sensorimotor areas and the posterior putamen, whereas standard-trained behaviors recruited the posterior caudate, insula, and prefrontal regions. A cortical network orchestrated habit expression (right S1 with the left anterior insula/prefrontal areas) while also implicating the basal ganglia when overriding habits (left premotor with the putamen). Importantly, stimulation of the left premotor cortex played a causal role in habit control, enhancing performance across both the training and devaluation phases. Our findings reveal an interaction between habitual and goal-directed brain regions, highlighting shared neural dynamics when overriding habitual behaviors.

•RT switch cost increases with overtraining, indexing human habit strength•fMRI reveals cortical-striatal networks for both habit expression and overriding•TMS shows a causal role of the premotor cortex in both habit acquisition and reversal•Computational modeling links automaticity to drift-diffusion decision parameters

RT switch cost increases with overtraining, indexing human habit strength

fMRI reveals cortical-striatal networks for both habit expression and overriding

TMS shows a causal role of the premotor cortex in both habit acquisition and reversal

Computational modeling links automaticity to drift-diffusion decision parameters

Behavioral neuroscience; Cognitive neuroscience; Medical imaging

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