Inhibiting the right dorsolateral prefrontal cortex selectively enhances unsupervised statistical learning

The brain must balance the automatic extraction of regularities with top-down cognitive control, yet the hemispheric contributions of the dorsolateral prefrontal cortex (DLPFC) remain unresolved. Here, we applied inhibitory repetitive transcranial magnetic stimulation to the left, right, or bilateral DLPFC in 95 adults during a probabilistic sequence learning task. We found that inhibiting the right and bilateral DLPFC enhanced statistical learning compared to sham stimulation. Contrary to the hypothesis that interference from existing knowledge would mediate this effect, episodic memory performance was unaffected. As an alternative, we propose that right DLPFC inhibition shifts cognitive processing toward an exploratory information-sampling strategy, supported by our finding of greater reaction time variability in the right and bilateral stimulation groups. Our results provide causal evidence for a right-lateralized suppressive influence of the DLPFC on unsupervised learning and suggest that its role is linked to information-processing style rather than direct competition with episodic memory systems.