Inverse effects of tDCS over the left versus right DLPC on emotional processing: A pupillometry study

PLoS One. 2019 Jun 19;14(6):e0218327. doi: 10.1371/journal.pone.0218327. eCollection 2019.

Abstract

Background and objectives: The Dorsolateral prefrontal cortex (DLPFC) is implicated in cognitive and emotional responses. Yet, research that investigates the causal role of the left versus right DLPFC during the processes of emotion appraisal is lacking. In the current study, transcranial direct current stimulation (tDCS) was used to disentangle the functional lateralization of the DLPFC on emotional processing in response to the anticipation of, and subsequent confrontation with emotional stimuli in healthy volunteers.

Methods: Forty-eight subjects received both active and sham (on separate days) anodal tDCS over either the left (N = 24) or right (N = 24) DLPFC. Subjects' pupil dilation (PD, a physiological marker of cognitive resource allocation) was recorded while performing an appraisal task in which negative and positive emotion eliciting images were presented, each preceded by an informative cue indicating the valence of the upcoming stimulus.

Results: As compared to sham stimulation, left DLPFC anodal tDCS resulted in increased PD when confronted with negative emotional images, whereas right DLPFC anodal tDCS resulted in decreased PD when confronted with emotional images, irrespective of valence.

Limitations: The interpretation of pupil dilation in response to emotional stimuli is limited.

Conclusion: These findings suggest inverse lateralized DLPFC effects on cognitive resource allocation (as measured by pupillary responses) when confronted with emotional stimuli. The current findings may shed some light on mechanisms that explain the antidepressant effects of non-invasive brain stimulation of the left DLPFC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Affect / physiology
  • Affect / radiation effects
  • Attention / physiology*
  • Cognition / physiology*
  • Emotions / physiology*
  • Emotions / radiation effects
  • Female
  • Healthy Volunteers
  • Humans
  • Male
  • Prefrontal Cortex / physiopathology
  • Prefrontal Cortex / radiation effects*
  • Transcranial Direct Current Stimulation / methods

Grants and funding

This research was supported by a grant BOF (BOFSTA2017002501) awarded to MAV, a grant FWO (ref. G044019N) awarded to MAV and RDR, a grant FWO (ref. 117438) awarded to AS, a grant BOF16/GOA/017 awarded to RDR, CB, and the Ghent University Multidisciplinary Research Partnership “The integrative neuroscience of behavioral control”. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.