Ultrasound neuromodulation reveals distinct roles of the dorsal anterior cingulate cortex and anterior insula in Pavlovian biases

Pavlovian biases reflect the notorious influence of hard-wired, evolutionarily conserved cue-response tendencies on instrumental action selection: people show automatic action invigoration in face of potential rewards, but action suppression in face of potential punishments. The neural origin of these biases is unclear. Past evidence suggests dorsal anterior cingulate cortex (dACC) and anterior insula (aIns) as part of a "reset network" that rapidly responds to salient information and might contribute to these biases. We used transcranial ultrasonic stimulation (TUS) in 29 healthy participants to interfere with neural activity in these regions and test their causal role in a within-subject, counter-balanced design across three sessions (sham, TUS-dACC, TUS-aIns). Computational modelling revealed a double dissociation, with distinct roles of both regions in Pavlovian biases: while TUS to the aIns decreased peoples tendency to overly take credit for rewards following action and to ignore punishments following inaction, TUS to dACC increased participants tendency to take the cue valence as a reinforcer signal. Although the dACC and aIns are part of the same network and often co-activate during decision-making tasks, TUS interference reveals their distinct roles: the dACC mediates cue-dependence persistence while the aIns is critical for inferring whether outcomes are self-caused.