Causal evidence for the role of dorsolateral prefrontal cortex in the implementation of cognitive control adjustments

Cognitive control processes enable us to use recent contextual information to flexibly adapt to current task demands. This ability to adapt control processes is exhibited in response conflict tasks. In these tasks, participants must respond to a relevant piece of information while overcoming the tendency to respond to task-irrelevant information that cues an automatic or habitual response. Control demands can be updated in these tasks via two separate routes. Both errors and conflict between task-irrelevant and task-relevant information affect performance on subsequent trials. A body of work has implicated dorsolateral prefrontal cortex (DLPFC) in implementing these control adjustments. However, this work has primarily relied on correlational techniques or focused on a single index of control adaptation. Here, we combine inhibitory transcranial magnetic stimulation (TMS) over DLPFC with computational modeling of behavior to test the causal role of DLPFC in control adaptation. We show that inhibitory TMS to DLPFC reduces the effect of previous trial conflict, and committing an error on the previous trial further reduces adaptive effects. This result provides causal evidence for DLPFC playing a general role in implementing trial-to-trial control adjustments.