Abstract
Despite being a commonly used protocol to treat major depressive disorder (MDD), the underlying mechanism of repetitive transcranial magnetic stimulation (rTMS) on dorsolateral prefrontal cortex (DLPFC) remains unclear. In the current study, we investigated the resting-state fMRI data of 100 healthy subjects by exploring three overlapping functional networks associated with the psychopathologically MDD-related areas (the nucleus accumbens, amygdala, and ventromedial prefrontal cortex). Our results showed that these networks converged at the bilateral DLPFC, which suggested that rTMS over DLPFC might improve MDD by remotely modulating the MDD-related areas synergistically. Additionally, they functionally converged at the DMPFC and bilateral insula which are known to be associated with MDD. These two areas could also be potential targets for rTMS treatment. Dynamic causal modelling (DCM) and Granger causality analysis (GCA) revealed that all pairwise connections among bilateral DLPFC, DMPFC, bilateral insula, and three psychopathologically MDD-related areas contained significant causality. The DCM results also suggested that most of the functional interactions between MDD-related areas and bilateral DLPFC, DMPFC, and bilateral insula can predominantly be explained by the effective connectivity from the psychopathologically MDD-related areas to the rTMS stimulation sites. Finally, we found the conventional functional connectivity to be a more representative measure to obtain connectivity parameters compared to GCA and DCM analysis. Our research helped inspecting the convergence of the functional networks related to a psychiatry disorder. The results identified potential targets for brain stimulation treatment and contributed to the optimization of patient-specific brain stimulation protocols.
Highlights
Repetitive transcranial magnetic stimulation is a noninvasive brain stimulation technique to modulate the neural plasticity of the brain
The symptomatology of major depressive disorder (MDD) is associated with dysfunction of the neural circuits which mediate reward, emotion, and decision making, involving the ventral tegmental area, nucleus accumbens (NAC), amygdala (AMY), and ventromedial prefrontal cortex (VMPFC) [11, 12], an idea supported by neuroimaging findings
We found the dorsolateral prefrontal cortex (DLPFC) to be functionally connected with MDDrelated brain areas in distinct ways
Summary
Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation technique to modulate the neural plasticity of the brain. Despite the increasing recognition of rTMS as a potent treatment for MDD, the neural mechanism underlying such success is still elusive. It is well known that MDD has a high comorbidity with anxiety disorders [10]. The symptomatology of MDD is associated with dysfunction of the neural circuits which mediate reward, emotion, and decision making, involving the ventral tegmental area, nucleus accumbens (NAC), amygdala (AMY), and ventromedial prefrontal cortex (VMPFC) [11, 12], an idea supported by neuroimaging findings. The known functions of the DLPFC, are not directly related to the core cognitive impairments found in MDD patients such as anhedonia, anxiety, and agitation [13,14,15]. Considered the absence of direct linkage between the DLPFC and core features of MDD, the positive influence of rTMS treatment on MDD patients is unlikely to be solely explained by modulations in DLPFC activities
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
