Enhance of Language Learning With Neurostimulation

The purpose of this study is to test the effect of transcranial direct current stimulation over the motor cortex of the language dominant hemisphere on language learning in healthy subjects and stroke patients with aphasia. We hypothesize that anodal stimulation enhances the learning of action words compared to sham and cathodal stimulation.

The motor cortex is involved at different levels of language processing. It has been demonstrated that the perception of action words activates motor representations in the language-dominant hemisphere. However, it is not known whether modulation of excitability has an effect on learning new action words. Thus, we hypothesize that transcranial direct current stimulation over the motor cortex of the language-dominant hemiphere modulates the acquisition of new action words. The results bear the potential to design new rehabilitative strategies in stroke patients with aphasia. The motor cortex might offer an access to the language network that can be used for interventional approaches such as neurostimulation.

anodal stimulation: 20 min during language learning, intensity: 1 mV, anodal electrode over primary motor cortex of language-dominant hemisphere, reference electrode over contralateral supraorbital area

anodal stimulation: 20 min during language learning, intensity: 1 mV, cathodal electrode over primary motor cortex of language-dominant hemisphere, reference electrode over contralateral supraorbital area

sham stimulation (placebo condition): 30 seconds during language learning, intensity: 1 mV, anodal electrode over primary motor cortex of language-dominant hemisphere, reference electrode over contralateral supraorbital area

DC Stimulator, Manufacturer:eldith -Electro-Diagnostic & Therapeutic Systems GmbH, Gustav-Kirchhoff-Straße 5, D-98693 Ilmenau, Serial number: 0006

1 mV for 20 min (verum conditions: anodal and cathodal)or 30 seconds (placebo condition: sham) during language learning , active electrode over primary motor cortex of language dominant hemisphere, reference electrode over contralateral supraorbital area

Inclusion Criteria: age >18 and < 86 years contractual capability ischemic stroke excluding motor cortex (stroke patients) minimum time since stroke 9 months aphasia (stroke patients) severe aphasia that impedes understanding of instructions (stroke patients) Exclusion Criteria: sever head trauma in the past seizures pace maker metal implants in the head/neck region severe comorbidity, especially neurologic and psychiatric diseases intake of illegal drugs Mini Mental State examination score < 27 neuroactive substances, e.g. antidepressants pregnancy

Branscheidt M, Hoppe J, Freundlieb N, Zwitserlood P, Liuzzi G. tDCS Over the Motor Cortex Shows Differential Effects on Action and Object Words in Associative Word Learning in Healthy Aging. Front Aging Neurosci. 2017 May 15;9:137. doi: 10.3389/fnagi.2017.00137. eCollection 2017.