Vergleichende Untersuchung der Effekte schwacher transkranieller Gleichstromstimulation in Abhängigkeit von der Händigkeit der Probanden

Comparing modulating effects of transcranial direct current stimulation due to subjects' handedness

by Sebastian Schade
Doctoral thesis
Date of Examination:2014-09-30
Date of issue:2014-09-05
Advisor:Prof. Dr. Andrea Antal
Referee:PD Dr. Dr. Till Manzke
Referee:Prof. Dr. Martin Oppermann
Persistent Address: http://dx.doi.org/10.53846/goediss-4668

 

 

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Abstract

English

Transcranial direct current stimulation (tDCS) has proven to be a useful tool for fundamental brain research as well as for attempts in therapy of neurological and psychiatric diseases by modulating neuronal plasticity. Little is understood how the effects of tDCS are influenced by hemispheric dominance, even less in terms of handedness. The aim of this study was to investigate whether tDCS induced neuroplastic changes may be different in right- and left-handed individuals due to existing differences in hemispheric lateralisation. We measured changes in motor evoked potentials (MEPs) after application of tDCS in 8 right-handers, 8 left-handers and 8 mixed-handers according to the Edinburgh Handedness Inventory (EHI). In double-blind sessions, we applied either anodal or cathodal tDCS for 5 minutes for each hemisphere. While motor thresholds (MT) seem to be not influenced by handedness significantly, in right-handed subjects we reproduced the well-known effects of tDCS: anodal stimulation increased while cathodal stimulation decreased MEP amplitudes. However, left-and mixed-handed subjects differed from right-handed subjects. After anodal stimulation of the left hemisphere the increase of the MEP amplitudes was stronger in right handed subjects than in left and mixed handed subjects. Interestingly, after cathodal stimulation of the left hemisphere this difference was less marked. The stimulation of the right hemisphere showed the same tendency, but results were not significant. For the first time, we are able to demonstrate that the modulating effects of tDCS on corticospinal excitability differ moderately in the left-and mixed-handed population compared to right-handed subjects. The shown differences according to handedness should be taken into account in further studies.
Keywords: Hemispheric asymmetry; handedness; Edinburgh Handedness Inventory (EHI); motor thresholds (MTs); motor evoked potentials (MEPs); transcranial direct current stimulation (tDCS)
Schlagwörter: hemisphärische Asymmetrie; Händigkeit; Edinburgh Handedness Inventory (EHI); motorisch evozierte Potentiale; transkranielle Gleichstromstimulation
 
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