HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Jefferson, S. Articles by Hamdy, S. PubMed PubMed Citation Articles by Jefferson, S. Articles by Hamdy, S.

Research Article

Characterising the application of transcranial direct current stimulation in human pharyngeal motor cortex

^{1 2}University of Manchester ³Institute of Neurology

Submitted 20 July 2009 ; revision received 2 October 2009 ; accepted in final form 2 October 2009

ABSTRACT

Objectives Transcranial direct current stimulation (tDCS) is a novel intervention that can modulate brain excitability in health and disease, however, little is known about its effects on bilaterally innervated systems such as pharyngeal motor cortex. Here, we assess the effects of differing doses of tDCS on the physiology of healthy human pharyngeal motor cortex as a prelude to designing a therapeutic intervention in dysphagic patients. Methods Healthy subjects (n=17) underwent seven regimens of tDCS (Anodal 10minutes 1mA, Cathodal 10minutes 1mA, Anodal 10minutes 1.5mA, Cathodal 10minutes 1.5mA, Anodal 20minutes 1mA, Cathodal 20minutes 1mA, Sham) on separate days, in a double blind randomised order. Bihemispheric motor evoked potential (MEP) responses to single-pulse transcranial magnetic stimulation (TMS) as well as intracortical facilitation (ICF) and inhibition (ICI) were recorded using a swallowed pharyngeal catheter before and up to 60 minutes following the tDCS. Results Compared to sham, both 10 minute 1.5mA and 20 minute 1mA anodal stimulation induced increases in cortical excitability in the stimulated hemisphere (+44 ±17% and +59 ±16% respectively, p<0.005) whereas only 10min 1.5mA cathodal stimulation induced inhibition (-26 ±4%, p=0.02). There were neither contralateral hemisphere changes nor any evidence for ICI or ICF in driving the ipsilateral effects. Conclusions Anodal tDCS can alter pharyngeal motor cortex excitability in an intensity dependent manner, with little evidence for transcallosal spread. Anodal stimulation may therefore provide a useful means of stimulating pharyngeal cortex and promoting recovery in dysphagic patients.

Pharynx; Plasticity; Swallowing