Causal role of angular gyrus and premotor cortex in human habit formation: A TMS study
Poster No:
118
Submission Type:
Abstract Submission
Authors:
xiaoyu Wang1, Hannes Ruge1, Katharina Zwosta1, Franziska Korb1, Uta Wolfensteller1
Institutions:
1Technische Universität Dresden, Dresden, Germany
First Author:
Co-Author(s):
Introduction:
Learning novel behaviors involves a complex transition from goal-related to habit-related brain systems which have been investigated and evidenced in animal studies [1]. However, how habits are formed and maintained in the human brain still remains unclear. For instance, Tricomi induced habitual behavior in humans via extensive training and successfully demonstrated a relationship between habit strength and increased activity in the posterior putamen (habitual system) [2]. However, these findings could not be replicated in a recent study using a larger data set [3]. Instead, other recent studies suggested that habit strength might be associated with decreasing engagement of the goal-directed brain system as learning progresses, such as the angular gyrus (AG) [4] or the head of the caudate [3]. The present study therefore aimed to probe the causal role of these two antagonistic brain systems during habit formation to investigate whether it relied on decreasing involvement of the goal-directed or on an increasing involvement of the habitual system. To this end, we used repetitive transcranial magnetic stimulation (rTMS) with AG and premotor cortex (PMC) as separate goal- and habit-directed stimulation targets. We assessed the behavioral and neural effects of rTMS on habit formation during a subsequent fMRI session.
Methods:
Fifty-one subjects (16 male, mean age: 24) were randomly divided into two groups (26 PMC and 25 AG). All took part in two separate sessions, receiving both real and sham stimulation. We used a slightly modified goal-habit paradigm which comprises three consecutive phases [4]. First, goal-directed behavior based on explicit stimulus-response-outcome associations was established. Subsequently, subjects received the off-line TMS stimulation (1Hz, 2 trains of 15 min, 1 min break) on either right AG (42 -57 36) or PMC (39 -6 48). After stimulation, participants were required to learn stimulus-response (S-R) associations via trial-and-error for a subset of the stimuli during scanning, for 98 repetitions per stimulus in order to induce strong S-R associations (habit formation). Finally, those habitual and goal-directed action tendencies were put into competition to measure the behavioral impact of habits on goal-directed behavior. ANOVAs were conducted to assess the stimulation effects on error rates and response times during habit formation and the later goal-habit competition. The learning-related changes in neural activity during the habit formation phase were modeled by parametric regressors reflecting the amount of training and examined by ANOVAs on the group level.
Results:
Behaviorally, error rates and reaction time decreased significantly during habit formation in general. Interestingly, AG stimulation resulted in an increased error rate specifically early on, though there was no significant interaction with block/time. Replicating previous findings, we found a generally decreasing activation in IPL, IFJ and anterior insula across training. However, TMS did not differentially influence those training induced changes. Most importantly, we found a significant accuracy-based compatibility interaction effect in the goal-habit competition phase (Figure 1b). Following AG stimulation, there was an increased competition between habitual and goal-directed action tendencies as evidenced by an increased compatibility effect compared to the sham stimulation. In contrast, following PMC stimulation, the competition was decreased. A similar pattern emerged for RTs following PMC stimulation (Figure 1c).
·Figure 1 TMS induced behavior changes in habit formation phase (a) and goal-habit competition phase derived from reaction time (b) and accuracy (c).
Conclusions:
Considering the goal-habit compatibility effect as a proxy for habit strength the current study successfully demonstrated a causal relationship between the involvement of the goal-directed and habit-related brain systems and human habit strength. More specifically, TMS reduced the habit strength when the habit system was disturbed by targeting PMC and increased habit strength when the goal-directed system was disturbed by targeting AG.
Brain Stimulation:
TMS 1
Emotion, Motivation and Social Neuroscience:
Reward and Punishment 2
Higher Cognitive Functions:
Executive Function, Cognitive Control and Decision Making
Higher Cognitive Functions Other
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI)
Keywords:
Cognition
FUNCTIONAL MRI
Learning
Transcranial Magnetic Stimulation (TMS)
1|2Indicates the priority used for review
Provide references using author date format
[2] Tricomi et al., 2009. A specific role for posterior dorsolateral striatum in human habit learning. Eur. J. Neurosci. 29 (11), 2225–2232.
[3] Gera et al., 2023. Characterizing habit learning in the human brain at the individual and group levels: A multi-modal MRI study. NeuroImage. 272, 120002.
[4] Zwosta et al., 2018. Habit strength is predicted by activity dynamics in goal-directed brain systems during training. Neuroimage 165, 125–137.