The Effects of taVNS on Motivation in MDD With Anhedonia

Inclusion Criteria: Meet the criteria of depression assessed by at least two psychiatrists according to the fifth version of Diagnostic and Statistical Manual of Mental Disorders. The score of Hamilton Depression Rating Scale-17 is larger than 18 and the score of the Apathy Evaluation scale is lager than 37. Patients were taking antidepressants--Selective Serotonin Reuptake Inhibitor(SSRIs) alone. Age was between 18 to 60 year old. The education duration was at least 6 years. The vision or corrected vision was normal. Right handedness. No treatment of rTMS, transcranial direct current stimulation, or electroconvulsive therapy before. Exclusion Criteria: History of significant head trauma or neurological disorders. Alcohol or drug abuse. Focal brain lesions. History of seizure. First degree relative with epilepsy, significant neurological illness or head trauma, endocrine disease. Significant unstable medical condition. Recent aggression or other forms of behavioral dyscontrol. Left-handedness. Pregnancy. Current alcohol or drug abuse Inability to provide informed consent. Patients with contraindications or factors affecting imaging quality, such as pacemakers, cochlear implants, or hearts Cerebrovascular metal stent, and metal denture.