Dopamine depletion effects on cognitive flexibility as modulated by tDCS of the dlPFC

Brain Stimul. 2020 Jan-Feb;13(1):105-108. doi: 10.1016/j.brs.2019.08.016. Epub 2019 Aug 31.

Abstract

Background: Recent evidence suggests that transcranial direct current stimulation (tDCS) may interact with the dopaminergic system to affect cognitive flexibility. Objective/hypotheses: We examined whether putative reduction of dopamine levels through the acute phenylalanine/tyrosine depletion (APTD) procedure and excitatory anodal tDCS of the dorsolateral prefrontal cortex (dlPFC) are causally related to cognitive flexibility as measured by task switching and reversal learning.

Method: A double-blind, sham-controlled, randomised trial was conducted to test the effects of combining anodal tDCS and depletion of catecholaminergic precursor tyrosine on cognitive flexibility.

Results: Anodal tDCS and tyrosine depletion had a significant effect on task switching, but not reversal learning. Whilst perseverative errors were significantly improved by anodal tDCS, the APTD impaired reaction times. Importantly, the combination of APTD and anodal tDCS resulted in cognitive performance which did not statistically differ to that of the control condition.

Conclusions: Our results suggest that the effects of tDCS on cognitive flexibility are modulated by dopaminergic tone.

Keywords: Dopamine depletion; Flexibility; Learning; Transcranial direct current stimulation; tDCS.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cognition*
  • Dopamine / blood
  • Dopamine / deficiency*
  • Female
  • Humans
  • Male
  • Prefrontal Cortex / physiology*
  • Reaction Time
  • Reversal Learning
  • Transcranial Direct Current Stimulation*
  • Tyrosine / blood
  • Tyrosine / deficiency
  • Young Adult

Substances

  • Tyrosine
  • Dopamine