title: Effects of transcranial direct current stimulation (tDCS) on behaviour and electrophysiology of language production.
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.
authors: University Hospital of Psychiatry, Department of Psychiatric Neurophysiology, Bern, Switzerland. Miranka.wirth@gmail.com
authors: Miranka
authors: M
authors: Wirth
authors: Rasha Abdel
authors: RA
authors: Rahman
authors: Janina
authors: J
authors: Kuenecke
authors: Thomas
authors: T
authors: Koenig
authors: Helge
authors: H
authors: Horn
authors: Werner
authors: W
authors: Sommer
authors: Thomas
authors: T
authors: Dierks
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001307:Auditory Perception; D001703:Biophysics; D004569:Electroencephalography / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007802:Language; D008297:Male; D009483:Neuropsychological Tests; D009862:Online Systems; D017397:Prefrontal Cortex / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D011795:Surveys and Questionnaires; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult