Functional role of dorsolateral prefrontal cortex in the modulation of cognitive bias.

Human cognition is often biased. It is a fundamental question in psychology how cognitive bias is modulated in the human brain. Automatic action tendency is a typical cognitive bias. The dorsolateral prefrontal cortex (DLPFC) is a crucial area for processing various behavioral tasks. We investigated the functional role of DLPFC in the modulation of cognitive bias by testing the automatic action tendency during automatic and regulated behavioral tasks. Unilateral intermittent or continuous theta burst stimulation (excitatory iTBS or inhibitory cTBS) was used to manipulate the left or right DLPFC excitability and assess the changes in automatic action tendency during a manikin task. An approaching behavior with positive stimulus and avoiding behavior with negative stimulus were performed in an automatic task. An approaching behavior with negative stimulus and avoiding behavior with positive stimulus were performed in a regulated task. Reaction time was measured. We confirmed the automatic action tendency that reaction time for performing an automatic task was shorter than that for performing a regulated task. The automatic action tendency was enhanced after left DLPFC excitatory iTBS and was abolished after left DLPFC inhibitory cTBS stimulation. On the other hand, right DLPFC excitatory iTBS accelerated the avoiding behaviors and right DLPFC inhibitory cTBS accelerated approaching behaviors. The results suggest that left DLPFC modulates the automatic action tendency while the right DLPFC modulates the direction of behavioral tasks. We conclude that left DLPFC and right DLPFC are key nodes in modulating the cognitive bias while their functional roles are different.