Network-nodal tACS induces right-lateralization of thalamocortical connectivity

Almost all functional processing in the cortex heavily relies on thalamic interactions. Since neural interactions across thalamocortical networks are essential for regulating cognitive functions, we investigated whether network-level transcranial alternating current stimulation (tACS) could modulate the functional connectivity of thalamocortical networks. Using network-node-based tACS and functional MRI (fMRI) data from the color flickering task, we performed functional connectivity and modularity analyses. Notably, tACS applied to key nodes of canonical functional networks resulted in right-lateralized thalamocortical connectivity. Compared to tACS applied to the medial prefrontal cortex (mPFC), tACS applied to the dorsolateral prefrontal cortex (dlPFC) significantly enhanced functional connectivity within the control and attentional networks. Further analyses of modularity and hub scores revealed functional clustering among early-order, late-order, and interactive thalamocortical modules, along with a significant enhancement in thalamocortical interplay within the cluster. TACS-to-dlPFC and tACS-to-mPFC enhanced interplay within the visual and control networks, respectively. Taken together, this study demonstrates the feasibility of network-based tACS for modulating task-relevant brain functional organization, with potential applications in cognitive impairment and clinical populations.