Modulating implicit food-related tendencies via repetitive TMS of the intraparietal sulcus. A proof-of-concept study for a novel therapeutic target in eating disorders.

AIM: Implicit approach-avoidance biases toward food play a key role in eating behaviors and may contribute to the development and maintenance of eating disorders. Yet, the neural mechanisms underlying these automatic responses remain poorly understood. The intraparietal sulcus (IPS) has been implicated in sensorimotor integration and goal-directed action, suggesting a role in regulating food-related behavioural biases.

OBJECTIVE

This proof-of-concept study aimed to investigate the causal role of the IPS in modulating implicit food-related approach-avoidance bias through low-frequency repetitive transcranial magnetic stimulation (rTMS).

METHODS

Twenty-two healthy individuals underwent three rTMS sessions in a randomized crossover design: active stimulation over the left and right IPS, and a sham control condition. Each active session consisted of low-frequency stimulation (1 Hz, 1200 pulses, lasting 20 min). After each session, participants completed a mobile version of the Approach-Avoidance Task, which involved pulling or pushing a smartphone in response to high-calorie and low-calorie food stimuli, and neutral objects.

RESULTS

Compared to the sham condition, rTMS over both the left and right IPS significantly enhanced approach bias toward high-calorie food stimuli. No significant changes were observed for low-calorie or neutral stimuli. These effects were not accompanied by changes in explicit food wanting ratings or in hunger levels.

CONCLUSIONS

These findings provide the first evidence for a causal role of the IPS in modulating implicit food-related behavioural biases. The IPS emerges as a promising neuromodulatory target for interventions aiming to rebalance maladaptive action tendencies in eating disorders and related conditions. Future research should explore the therapeutic potential of IPS-targeted stimulation protocols in clinical populations.