Related Experiment Video
Updated: Oct 3, 2026
Individualized rTMS Treatment for Depression using an fMRI-Based Targeting Method
Published on: August 2, 2021
Fronto-cingulate gamma synchrony predicts deep brain stimulation response in treatment-resistant depression:
Fatemeh Gholamali Nezhad1, Ishaan Tailor1, Sina Chegini1
1Interventional Psychiatry Program, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada.
Background:
Gamma-band activity has been linked to cognitive-affective processing in depression. However, its role in deep brain stimulation (DBS) response in treatment-resistant depression (TRD) remains unclear. This exploratory study investigated whether ventral capsule/ventral striatum DBS (VCVS-DBS) modulates gamma activity during cognitive-affective processing and whether DBS-related gamma changes are associated with improvement in depressive symptoms.
Methods:
Seven participants with TRD completed an affective Multi-Source Interference Task during DBS ON and OFF. Source-localized electroencephalography estimated local gamma power, synchrony, and effective connectivity in fronto-cingulate regions. DBS- and task-related effects were identified with cluster-based permutation testing, and follow-up analyses used Bayesian modeling.
Results:
During cognitive control under affective context, VCVS-DBS was associated with increased mid-gamma (41-55 Hz) power in left dorsal anterior cingulate cortex (L-dACC) and right ventrolateral prefrontal cortex (R-VLPFC) after affective stimuli. In the time window where power increases overlapped (0.76-0.86 s), DBS was also associated with increased mid-gamma synchrony between these regions. The DBS-related increase in synchrony-not local power-was associated with clinical improvement (Bayesian Spearman ρ = 0.52). Granger causality further indicated that effective connectivity shifted toward greater L-dACC influence over R-VLPFC during DBS. Exploratory cross-validation suggested that DBS-related synchrony change and baseline effective connectivity together accounted for individual differences in clinical improvement.
Limitations:
The primary limitation was the necessarily small sample size, which was partially addressed using Bayesian analyses leveraging extensive within-participant data.
Conclusions:
These preliminary findings suggest that VCVS-DBS may engage a fronto-cingulate gamma network involved in cognitive-affective control in TRD. They further suggest that clinical response may depend on both baseline dACC-VLPFC network organization and DBS-related modulation of gamma synchrony, highlighting potential relevance to cognitive-affective regulation across psychiatric disorders. Given the small sample size, these findings should be considered hypothesis-generating and require confirmation in larger cohorts.
