Prolonged longitudinal transcutaneous auricular vagus nerve stimulation effects on striatal functional connectivity in patients with major depressive disorder

Abstract

The cortical-striatal abnormalities are commomly found in the mental disorders. Instant transcutaneous auricular vagus nerve stimulation (taVNS) has been found to modulate the ventral striatial functional connectivity (FC) in patients with major depressive disorder (MDD). However, the neural mechanism of prolonged longitudinal taVNS treatment on different striatal subregions has not yet been elucidated. We used resting state functional magnetic resonance to estimate the effect of taVNS on the FC of striatal subregions in patients with MDD. Compared with healthy control subjects, lower prefrontal-striatal rsFC and higher occipital-striatal rsFC were found in patients with MDD. While the prefrontal-striatal rsFC increased and the occipital-striatal rsFC decreased after taVNS treatment. Specifically, the decreased Hamilton Depression Scale (HAMD) scores were positive correlated with the change of rsFCs between left ventral caudate (vCa) and right ventral prefrontal cortex (vPFC), and negatively correlated with the change of rsFCs between left vCa and right superior occipital gyrus. The rsFC between right nucleus accumbens (NAc)and right dorsal medial prefrontal cortex (dmPFC)at baseline predicted the longitudinal taVNS effects on HAMD score at 8 weeks. Therefore, taVNS can relief depressive sympotoms by modulating the aberrant striatal rsFC in patients with MDD. The strength of rsFC between the right NAc and right dmPFC may serve as a potential biomarker for the prolonged longitudinal taVNS and predict treatment responses.