Right DLPFC stimulation attenuates negative evaluation in social anxiety: An rTMS study

Social anxiety is characterized by excessive fear generalization to social evaluation. Although rTMS shows promise in modulating anxiety, its effects on negative evaluation in social anxiety remain unclear. This study investigated if rTMS targeting the right DLPFC could modulate negative evaluation expectancy in individuals with high social anxiety.

Using a randomized controlled design, 33 individuals with high social anxiety (LSAS ≥38) were randomly assigned to rTMS (n = 15) or sham (n = 18) groups. Single-session 1 Hz rTMS (1200 pulses, 80% RMT) was applied to the right dorsolateral prefrontal cortex (DLPFC) using neuronavigation. Expectancy ratings for conditioned (CS+/CS-) and generalization (GS1-4) stimuli were assessed during early and late generalization.

Both groups demonstrated successful acquisition. During generalization, significant main effects for time and stimulus type were observed. Critically, the rTMS group showed lower US-expectancy ratings than sham selectively for the intermediate-similarity stimulus (GS3) during early generalization, with no group differences for other stimuli or in the late phase. Polynomial trend analyses revealed a significant time × group interaction in the quadratic (curvature) component, reflecting an early-phase between-group difference in curvature.

Offline 1 Hz rTMS over the right DLPFC modulated negative-evaluation generalization in a phase- and stimulus-specific manner. The findings suggest right-DLPFC stimulation primarily influences the shape of the early generalization gradient under ambiguity, rather than producing a uniform reduction across stimuli. Durability and clinical relevance require further investigation.