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.

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