This study will investigate the cortical hemodynamic response variability of an accelerated form of TBS stimulation over left dorsolateral prefrontal cortex (DLPFC) using a concurrent TBS/fNIRS setup. The accelerating TMS protocol that will be used in this study is similar to the Stanford Accelerated Intelligent Neuromodulation Therapy (SAINT), i.e., fifty iTBS sessions (1,800 pulses per session, 50-minute intersession interval) will be delivered as 10 daily sessions over 5 consecutive days at 90% resting motor threshold. The investigators will recruit a depressed patient and conduct a concurrent iTBS/fNIRS protocol for each iTBS session. Moreover, the depression symptoms of the patient will be assessed before and after treatment.

Inclusion Criteria:

• aged 18 to 65;
• a clinical diagnosis of current nonpsychotic major depressive disorder by an experienced psychiatrist according to DSM-IV;
• no or stable (≥2 weeks) psychopharmacological medication;
• have not responded to at least one antidepressant medication;
• have not received any TMS treatment;
• and have a 17-item HAMD score ≥ 20.

Exclusion Criteria:

• severe internal diseases;
• neurological disorders or a history of severe head injuries;
• having suicidal ideation;
• pregnancy;
• common MRI, fNIRS and TMS exclusion criteria, such as a history of brain surgery, head injury, cardiac pacemaker, deep brain stimulation, intracranial metallic particles, history of seizures
• antiepileptics and benzodiazepines corresponding to a dose of >1 mg lorazepam/d.