Modulation of large-scale cortical coupling by transcranial alternating current stimulation

TY - JOUR

T1 - Modulation of large-scale cortical coupling by transcranial alternating current stimulation

AU - Schwab, Bettina

AU - Misselhorn, Jonas

AU - Engel, Andreas Karl

PY - 2019

Y1 - 2019

N2 - Background: Long-range functional connectivity in the brain is considered fundamental for cognition andis known to be altered in many neuropsychiatric disorders. To modify such coupling independent ofsensory input, noninvasive brain stimulation could be of utmost value.Objective: First, we tested if transcranial alternating current stimulation (tACS) is able to influencefunctional connectivity in the human brain. Second, we investigated the specificity of effects in frequencyand space.Methods: Participants were stimulated bifocally with high-definition tACS in counterbalanced order (1)in-phase, with identical electric fields in both hemispheres, (2) anti-phase, with phase-reversed electricfields in the two hemispheres, and (3) jittered-phase, generated by subtle frequency shifts continuouslychanging the phase relation between the two fields. EEG aftereffects were analyzed systematically insensor and source space.Results: While total power and spatial distribution of the fields were comparable between conditions,global pre-post stimulation changes in EEG connectivity were larger after in-phase stimulation than afteranti-phase or jittered-phase stimulation. Those differences in connectivity were restricted to the stimulatedfrequency band and decayed within the first 120 s after stimulation offset. Source reconstructionlocalized the maximum effect between the stimulated occipito-parietal areas.Conclusion: The relative phase of bifocal alpha-tACS modulated alpha-band connectivity between thetargeted regions. As side effects are not expected to differ between the stimulation conditions, weconclude that neural activity was phase-specifically influenced by the electric fields. We thus suggestbifocal high-definition tACS as a tool to manipulate long-range cortico-cortical coupling which outlaststhe stimulation period.

AB - Background: Long-range functional connectivity in the brain is considered fundamental for cognition andis known to be altered in many neuropsychiatric disorders. To modify such coupling independent ofsensory input, noninvasive brain stimulation could be of utmost value.Objective: First, we tested if transcranial alternating current stimulation (tACS) is able to influencefunctional connectivity in the human brain. Second, we investigated the specificity of effects in frequencyand space.Methods: Participants were stimulated bifocally with high-definition tACS in counterbalanced order (1)in-phase, with identical electric fields in both hemispheres, (2) anti-phase, with phase-reversed electricfields in the two hemispheres, and (3) jittered-phase, generated by subtle frequency shifts continuouslychanging the phase relation between the two fields. EEG aftereffects were analyzed systematically insensor and source space.Results: While total power and spatial distribution of the fields were comparable between conditions,global pre-post stimulation changes in EEG connectivity were larger after in-phase stimulation than afteranti-phase or jittered-phase stimulation. Those differences in connectivity were restricted to the stimulatedfrequency band and decayed within the first 120 s after stimulation offset. Source reconstructionlocalized the maximum effect between the stimulated occipito-parietal areas.Conclusion: The relative phase of bifocal alpha-tACS modulated alpha-band connectivity between thetargeted regions. As side effects are not expected to differ between the stimulation conditions, weconclude that neural activity was phase-specifically influenced by the electric fields. We thus suggestbifocal high-definition tACS as a tool to manipulate long-range cortico-cortical coupling which outlaststhe stimulation period.

M3 - SCORING: Journal article

JO - BRAIN STIMUL

JF - BRAIN STIMUL

SN - 1935-861X

ER -