Effects of transcranial direct current stimulation (tDCS) on behaviour and electrophysiology of language production

Neuropsychologia. 2011 Dec;49(14):3989-98. doi: 10.1016/j.neuropsychologia.2011.10.015. Epub 2011 Oct 21.

Abstract

Excitatory anodal transcranial direct current stimulation (A-tDCS) over the left dorsal prefrontal cortex (DPFC) has been shown to improve language production. The present study examined neurophysiological underpinnings of this effect. In a single-blinded within-subject design, we traced effects of A-tDCS compared to sham stimulation over the left DPFC using electrophysiological and behavioural correlates during overt picture naming. Online effects were examined during A-tDCS by employing the semantic interference (SI-)Effect - a marker that denotes the functional integrity of the language system. The behavioural SI-Effect was found to be reduced, whereas the electrophysiological SI-Effect was enhanced over left compared to right temporal scalp-electrode sites. This modulation is suggested to reflect a superior tuning of neural responses within language-related generators. After -(offline) effects of A-tDCS were detected in the delta frequency band, a marker of neural inhibition. After A-tDCS there was a reduction in delta activity during picture naming and the resting state, interpreted to indicate neural disinhibition. Together, these findings demonstrate electrophysiological modulations induced by A-tDCS of the left DPFC. They suggest that A-tDCS is capable of enhancing neural processes during and after application. The present functional and oscillatory neural markers could detect positive effects of prefrontal A-tDCS, which could be of use in the neuro-rehabilitation of frontal language functions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Analysis of Variance
  • Auditory Perception
  • Biophysics
  • Electroencephalography / methods
  • Evoked Potentials / physiology*
  • Female
  • Functional Laterality
  • Humans
  • Language*
  • Male
  • Neuropsychological Tests
  • Online Systems
  • Prefrontal Cortex / physiology*
  • Reaction Time / physiology*
  • Surveys and Questionnaires
  • Transcranial Magnetic Stimulation*
  • Young Adult