Left DLPFC rTMS stimulation reduced the anxiety bias effect or how to restore the positive memory processing in high-anxiety subjects

In the present research we explored the role of the dorsolateral prefrontal cortex (DLPFC) in memory retrieval process of positive vs. negative emotional stimulus, as a function of the anxiety levels. Anxiety behavior showed a consistent attentional bias toward negative and aversive memories, induced by a right frontal cortical superiority. This effect was analyzed by using a rTMS paradigm that induced a cortical activation of the left DLPFC. Subjects, who were divided in two different groups depending on their anxiety level (high/low-anxiety, State-Trait-Anxiety-Inventory, STAI), were required to perform a task consisting of two experimental phases: an encoding-phase, where some lists composed by positive and negative emotional words were presented to the subjects; and a retrieval-phase, where the old stimuli and new stimuli were presented for a recognition performance. We found that the rTMS stimulation affects the memory retrieval of emotional material. High-anxiety subjects benefit in greater measure from the left DLPFC stimulation with a reduced negative bias. This result suggested that left DLPFC activation favors the memory retrieval of positive emotional information and might limit the “unbalance effect” induced by a right hemispheric superiority at a high level of anxiety. The potentiality of TMS for anxiety behavior modulation was also discussed.