Muscle evoked potentials (MEP) are supposed to different in schizophrenic and depressed patients, compared to a sample of healthy volunteers. Transcranial Magnetic Stimulation (TMS)-evoked MEP are measured in all three groups at baseline and after tDCS (2 mA, 20 minutes). MEP amplitudes are supposed to normalize quickly in healthy volunteers, to stay diminished in depressed patients and to stay elevated in schizophrenic patients. These differences should disappear after regular pharmacological treatment. Outcome measures will be done in week 2 and week 4.

Inclusion Criteria:

• The patient must be in the condition to understand the patient-information, as well as the necessary examinations.
• He/she must be able to give a written consent.
• No medication at least three weeks before enrollment.

Exclusion Criteria:

• Existence of a care/legal incapacity
• Existing pregnancy
• Severe psychiatric illness (with exception of affective disorder)
• Acute suicidality
• Drug-, medication- or alcohol dependence
• Dementia according to DSM IV / ICD 10-criterions
• Severe brain infarctus in the anamnesis
• Indications of structural damage of the basal ganglia or the brain stem
• Severe neurological disorders (e.g. M. Parkinson, epilepsy, discus-prolapse, dementia, systemic neurological illnesses, normal pressure hydrocephalus, cerebrovascular diseases, elevated intracranial pressure, in the last 6 months, polyneuropathies).
• Severe other medical conditions, like manifest arterial hypertonia, severe heart disease, pacemakers, respiratory failure, malignant illnesses all type, also in the history, active infectious diseases, skeletal disorders (like M. Paget, osteoporosis with spontaneous fractures, fresh fractures) Other circumstances, that speaks against a participation of the patient pinion of Medical Doctor at this study.

15 depressed patients 15 schizophrenic patients 15 healthy volunteers