When brain stimulation backfires: the effects of prefrontal cortex stimulation on impulsivity

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychopharmacology

Background:

• Transcranial direct current stimulation (tDCS) is a neuromodulation technique with potential therapeutic applications.
• Individual differences in personality and neurochemistry, particularly dopamine levels, may influence tDCS efficacy and lead to paradoxical effects.
• Previous research indicates a link between dopamine and tDCS outcomes.

Purpose of the Study:

• To investigate the role of personality traits, specifically impulsivity, in modulating the effects of anodal tDCS on the prefrontal cortex.
• To explore whether dopamine-related facets of impulsivity predict reverse tDCS effects.

Main Methods:

• 124 healthy participants completed the UPPS Impulsive Behavior Scale.
• Participants received a single session of anodal or sham tDCS over the prefrontal cortex.
• State impulsivity was assessed using the Stop Signal Task while tDCS effects were active.

Main Results:

• tDCS led to increased errors on the Stop Signal Task in individuals scoring high on specific UPPS impulsivity facets linked to dopamine.
• No significant effects of tDCS were observed in participants with low trait impulsivity.
• These findings suggest that high trait impulsivity, particularly dopamine-related aspects, may predict reverse tDCS effects.

Conclusions:

• Inter-individual differences in personality and neurochemistry, specifically dopamine-related impulsivity, are associated with the reverse effects of tDCS.
• Understanding these individual differences is crucial for predicting and potentially mitigating unintended tDCS outcomes.
• Future research should further elucidate the neurochemical underpinnings of tDCS response variability.