Depression is the most common psychiatric condition and a important public health concern in society. But medications for depression don't work as well as people expected and cause serious side-effects. Transcranial magnetic stimulation (TMS) is a noninvasive electrical stimulation treatment for depression, which has been approved by the FDA and added to the Guidelines for the Treatment of Depression in China. Despite the effect of the treatment is clear ,the TMS target,the neural circuit which plays a role in TMS and its mechanism remain unknown now. TBS target and effective site may be not in the same position. A large number of previous studies demonstrate the advantages and application prospects of different techniques of magnetic resonance (MR)in the study of pathogenesis of depression. Based on the results of previous research supported by the National Natural Science Foundation of China,the National Key Technology Research and Development Program of China during the "10th Five-Year Plan" and New Health Care and New technology. project team puts forward the idea of joint use of brain structure imaging of MR ,Diffusion Tensor Imaging (DTI) and resting-state functional MRI (fMRI) with different analysis methods to conduct a comprehensive study. The study is focused on the effects of TBS treatment on brain structure network, fiber connectivity network and functional connectivity network ,and nodes affected by it. Then we make further investigation about the mechanism of TMS treatment. The research will provide not only help for studying the pathogenesis of depression but also more reliable targets of next TMS treatment.

The advantages of 3D T1 WI are thin slice scan，no interval, scanning fast and three-dimension reconstruction in any orientation compared with 2D SE. It is not easy to miss small lesions, and shows normal anatomy and lesions more objectively and more accurately.

Doppler tissue imaging (DTI) can reflect white matter fiber so that can be used to determine whether the various diseases affect nerve cell connections.

Arterial spin labeling (ASL) is non-drug perfusion imaging and completely noninvasive technology which can reflect brain perfusion better.

Resting-state functional MRI (fMRI) is used to located the abnormal brain regions whose activity is consistent with dorsolateral prefrontal cortex (DLPFC) by the abnormal resting spontaneous brain activity in patients with depression and the abnormal functional connectivity network.

Inclusion Criteria:

TMS treatment group and medication group:

1. Hospitalized patients or outpatients which meet Clinical diagnosis of depression such as international Classification of diseases-10( ICD-10) which is the diagnostic criteria of unipolar depression;Scores of Hamilton Depression Scale (HAMD) ≥ 18 points, scores of clinical total impression scale (CGI)≥ 3 points, and without severe suicidal tendency;
2. 18-60 years old, male or female;
3. Physical and laboratory examination, electrocardiogram(ECG),and electroencephalogram (EEG) with no abnormal changes;
4. No serious or unstable cerebrovascular, liver, kidney, endocrine, blood and other somatic diseases;
5. The patient or the legal guardian should sign a written informed consent after fully understanding the research content of this study.

Healthy control group:

1. 18-60 years old, male or female;
2. Physical and laboratory examination, electrocardiogram(ECG),and electroencephalogram (EEG) with no abnormal changes;
3. No serious or unstable heart, liver, kidney, endocrine, blood and other somatic diseases;
4. Subjects or their legal guardians sign written informed consents after fully understanding the research contents of this study.

Exclusion Criteria:

1. Mental disorders caused by organic diseases such as brain tumors;
2. Serious somatic diseases, severe suicidal tendency and pacemakers;
3. Secondary depressive disorder, psychotic depression or bipolar disorder caused by drugs;
4. Antidepressants or psychoactive drugs were taken one month before enrollment.