What question did this study set out to answer?

To assess if deep TMS inhibits the right PCC and modulates DMN connectivity in healthy adults.

April 26, 2026SHILAP Revista de lepidopterología0 citationsOpen Access

Modulating the default mode network with deep TMS: a proof-of-concept framework with potential relevance to circuits implicated in lack of awareness of cognitive decline

YBYoussef BellaaliUCLouvain DŠDominika ŠulcováUCLouvain ASAdriana SalatinoRoyal Military Academy

Key Points

To assess if deep TMS inhibits the right PCC and modulates DMN connectivity in healthy adults.
Twelve right-handed healthy participants underwent two randomized sessions: deep TMS and sham condition.
Resting-state fMRI was acquired 10-20 minutes post-stimulation to analyze connectivity changes.
Connectivity was assessed through correlation-matrix analysis and whole-brain seed-based paired t-test.
Reduced connectivity was observed between the PCC and three DMN-related regions post deep TMS, but did not survive correction.
Whole-brain analysis showed eight clusters with significantly decreased connectivity, including six key DMN hubs.

Abstract

Introduction Self-referential processes are suspected to rely on the default mode network (DMN), particularly the posterior cingulate cortex (PCC). The right PCC, has been implicated in self-awareness, with neuroimaging studies showing its involvement in anosognosia in Alzheimer’s disease. However, causal evidence linking right PCC activity to DMN synchrony in humans remains scarce. This study examined whether transient modulation of the right PCC using continuous theta-burst deep transcranial magnetic stimulation (deep TMS) alters DMN connectivity in healthy adults. Aim To assess whether transient inhibition of the right PCC using continuous theta-burst deep transcranial magnetic stimulation (deep TMS) modulates DMN functional connectivity in healthy adults. Methods Twelve right-handed healthy participants (aged 26–30 years) underwent two randomized sessions: deep TMS targeting the right PCC and a sham condition. Resting-state fMRI was acquired 10–20 min post-stimulation. Connectivity changes were assessed through (1) a correlation-matrix analysis between the right PCC and 78 regions of the Brainnetome atlas, and (2) a whole-brain seed-based paired t -test. For the whole-brain analysis, statistical significance was determined using cluster-level Monte-Carlo correction ( p 0.05). Results The region-based correlation matrix showed reduced connectivity between the PCC and three DMN-related regions (right precuneus, right inferior parietal gyrus, left superior temporal gyrus), although these did not survive multiple-comparison correction. The whole-brain analysis revealed eight clusters with significantly decreased connectivity after stimulation compared to sham, including six key DMN hubs (bilateral precuneus, bilateral supramarginal gyri, right angular gyrus, left posterior superior temporal gyrus). Conclusion Deep TMS of the right PCC induced a transient desynchronization of DMN connectivity, supporting a causal contribution of the right PCC to large-scale self-referential network integrity. While no behavioral evaluation was performed at this stage, these results provide a proof-of-principle that transient modulation of the right PCC can alter DMN synchrony, opening the way for future studies combining deep TMS with metacognitive and self-awareness assessments to directly investigate awareness mechanisms in healthy aging and neurodegenerative disease.

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