Rafique, SaraSteeves, Jennifer Kate Evelyn2025-02-062025-02-062022-01-20Rafique, S. A., & Steeves, J. K. E. (2022). Modulating intrinsic functional connectivity with visual cortex using low‐frequency repetitive transcranial magnetic stimulation. Brain and Behavior, 12(2), Article e2491. https://doi.org/10.1002/brb3.24912162-32792162-3279https://doi.org/10.1002/brb3.2491https://hdl.handle.net/10315/42625Introduction: Intrinsic network connectivity becomes altered in pathophysiology. Noninvasive brain stimulation can modulate pathological functional networks in an attempt to restore the inherent response. To determine its usefulness for visual-related disorders, we developed procedures investigating repetitive transcranial magnetic stimulation (rTMS) protocols targeting the visual cortex on modulating connectivity associated with the visual network and default mode network (DMN). Methods: We compared two low-frequency (1 Hz) rTMS protocols to the visual cortex (V1)—a single 20 min session and five successive 20 min sessions (accelerated/within-session rTMS)—using multi-echo resting-state functional magnetic resonance whole-brain imaging and resting-state functional connectivity (rsFC). We also explored the relationship between rsFC and rTMS-induced changes in key inhibitory and excitatory neurotransmitters, γ-aminobutyric acid (GABA) and glutamate. GABA (GABA+) and glutamate (Glx) concentrations were measured in vivo using magnetic resonance spectroscopy. Results: Acute disruption with a single rTMS session caused widespread connectivity reconfiguration with nodes of interest. Changes were not evident immediately post-rTMS but were observed at 1 h post-rTMS. Accelerated sessions resulted in weak alterations in connectivity, producing a relatively homeostatic response. Changes in GABA+ and Glx concentrations with network connectivity were dependent on the rTMS protocol. Conclusions: This proof-of-concept study offers new perspectives to assess stimulation-induced neural processes involved in intrinsic functional connectivity and the potential for rTMS to modulate nodes interconnected with the visual cortex. The differential effects of single-session and accelerated rTMS on physiological markers are crucial for furthering the advancement of treatment modalities in visual cortex related disorders.enAttribution 4.0 InternationalAccelerated rTMSFunctional connectivityGABAGlutamateRepetitive TMSResting-state fMRIVisual cortexArticle