Prefrontal cortex stimulation does not affect emotional bias, but may slow emotion identification.
Transcranial direct current stimulation (tDCS) has recently garnered attention as a putative depression treatment. However, the cognitive mechanisms by which it exerts an antidepressant effect are unclear: tDCS may directly alter 'hot' emotional processing biases, or alleviate depression through changes in 'cold' (non-emotional) cognitive function. Here, 75 healthy participants performed a facial emotion identification task during 20 minutes of anodal or sham tDCS over the left dorsolateral prefrontal cortex (DLPFC) in a double-blind, within-subject crossover design. A subset of 31 participants additionally completed a task measuring attentional distraction during stimulation. Compared to sham stimulation, anodal tDCS of the left DLPFC resulted in an increase in response latency across all emotional conditions. Bayesian analysis showed definitively that tDCS exerted no emotion-dependent effect on behaviour. Thus, we demonstrate that anodal tDCS produces a general, rather than an emotion-specific, effect. We also report a preliminary finding in the subset of participants who completed the distractibility task: increased distractibility during active stimulation correlated significantly with the degree to which tDCS slowed emotion identification. Our results provide insight into the possible mechanisms by which DLPFC tDCS may treat symptoms of depression, suggesting that it may not alter emotional biases, but instead may affect 'cold' cognitive processes.
Institute of Cognitive Neuroscience, University College London, London, UK.
Camilla L
CL
Nord
School of Psychology, University of Sussex, Brighton, UK.
Sophie
S
Forster
Institute of Cognitive Neuroscience, University College London, London, UK.
D Chamith
DC
Halahakoon
School of Experimental Psychology, University of Bristol, Bristol, UK.
Ian S
IS
Penton-Voak
School of Experimental Psychology, University of Bristol, Bristol, UK.|MRC Integrative Epidemiology Unit at the University of Bristol, Bristol, UK.
Marcus R
MR
Munafò
Institute of Cognitive Neuroscience, University College London, London, UK.
Jonathan P
JP
Roiser
D000328:Adult; D001288:Attention / Q000502:physiology; D001499:Bayes Theorem; D018592:Cross-Over Studies; D003863:Depression / Q000523:psychology; D004311:Double-Blind Method; D004644:Emotions / Q000502:physiology*; D005149:Facial Expression; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D017397:Prefrontal Cortex / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012938:Social Perception; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult
DLPFC; depression; distractibility; tDCS