Objective      To determine the alterations of brain spontaneous functional connectivity (FC) and investigate the underlying neural mechanism of psychotherapy in patients with major depressive disorder (MDD) by fractional amplitude of low-frequency (fALFF) and FC in resting-state functional magnetic resonance imaging (fMRI).       Methods      A total of 23 MDD patients and 20 healthy controls with matched age

sex and education were enrolled in this study for 4-week guided imagery psychotherapy. Their resting-state functional magnetic resonance data were acquired before and after the intervention. Longitudinal changes of fALFF and FC were assessed based on the whole-brain voxel.       Results      After 4-week psychotherapy

86.9% of patients achieved definite remission. The MDD patients showed obvious fALFF increase in the bilateral orbitofrontal cortex and right paracentral lobule when compared with the healthy controls

and no change was seen after psychotherapy. After the treatment

the spontaneous FC was obviously reduced in the dorsal anterior cingulate cortex and subgenual cingulate cortex

and that in the dorsal anterior cingulate cortex

right dorsolateral prefrontal cortex

subgenual cingulate cortex and left supplementary motor area was significantly enhanced after the intervention. The fALFF of the subgenual cingulate cortex was positively correlated with Hamilton depression scale (HDRS) after psychotherapy (r=0.498

P=0.015).       Conclusion      Psychotherapy alters the coupling and connectivity in FC of vital nodes to restore the emotional-specific network. In the process

the frontocingulate is the critical area in the functional network for MDD patients

and the top-down regulatory mode might be the key mechanism for psychotherapy.