Bifocal tACS over the primary sensorimotor cortices increases interhemispheric inhibition and improves bimanual dexterity

Hakuei Fujiyama; Brooke Lebihan

doi:10.1093/cercor/bhaf011

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Bifocal tACS over the primary sensorimotor cortices increases interhemispheric inhibition and improves bimanual dexterity

Journal article

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Bifocal tACS over the primary sensorimotor cortices increases interhemispheric inhibition and improves bimanual dexterity

Hakuei Fujiyama and Brooke Lebihan

Cerebral Cortex, Vol.35(2), bhaf011

2025

DOI: https://doi.org/10.1093/cercor/bhaf011

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Abstract

electroencephalogram

functional connectivity

interhemispheric inhibition

transcranial alternating current stimulation

transcranial magnetic stimulation

Concurrent application of transcranial alternating current stimulation over distant cortical regions has been shown to modulate functional connectivity between stimulated regions; however, the precise mechanisms remain unclear. Here, we investigated how bifocal transcranial alternating current stimulation applied over the bilateral primary sensorimotor cortices modulates connectivity between the left and right primary motor cortices (M1). Using a cross-over sham-controlled triple-blind design, 37 (27 female, age: 18 to 37 yrs) healthy participants received transcranial alternating current stimulation (1.0 mA, 20 Hz, 20 min) over the bilateral sensorimotor cortices. Before and after transcranial alternating current stimulation, functional connectivity between the left and right M1s was assessed using imaginary coherence measured via resting-state electroencephalography and interhemispheric inhibition via dual-site transcranial magnetic stimulation protocol. Additionally, manual dexterity was assessed using the Purdue pegboard task. While imaginary coherence remained unchanged after stimulation, beta (20 Hz) power decreased during the transcranial alternating current stimulation session. Bifocal transcranial alternating current stimulation but not sham strengthened interhemispheric inhibition between the left and right M1s and improved bimanual assembly performance. These results suggest that improvement in bimanual performance may be explained by modulation in interhemispheric inhibition, rather than by coupling in the oscillatory activity. As functional connectivity underlies many clinical symptoms in neurological and psychiatric disorders, these findings are invaluable in developing noninvasive therapeutic interventions that target neural networks to alleviate symptoms.

Details

Title: Bifocal tACS over the primary sensorimotor cortices increases interhemispheric inhibition and improves bimanual dexterity
Authors/Creators: Hakuei Fujiyama - Murdoch University, Centre for Healthy Ageing
Brooke Lebihan
Publication Details: Cerebral Cortex, Vol.35(2), bhaf011
Publisher: Oxford University Press
Number of pages: 15
Grant note: Neurotrauma Research Program: DoH20193370 Sarich Family Research Fellowship
This work was supported by the Neurotrauma Research Program (DoH20193370) awarded to H.F. and A.D.T. A.D.T. was supported by a Sarich Family Research Fellowship.
Identifiers: 991005735928207891
Murdoch Affiliation: School of Psychology; Centre for Healthy Ageing; Personalised Medicine Centre
Language: English
Resource Type: Journal article

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Collaboration types: Domestic collaboration; International collaboration
Citation topics: 1 Clinical & Life Sciences; 1.82 Gait & Posture; 1.82.811 Transcranial Magnetic Stimulation
Web Of Science research areas: Neurosciences
ESI research areas: Neuroscience & Behavior