Subcortical substrates of TMS induced modulation of the cortico-cortical connectivity

TY - JOUR

T1 - Subcortical substrates of TMS induced modulation of the cortico-cortical connectivity

AU - Groppa, Sergiu

AU - Muthuraman, Muthuraman

AU - Otto, Birte

AU - Deuschl, Günther

AU - Siebner, Hartwig R

AU - Raethjen, Jan

PY - 2013/3

Y1 - 2013/3

N2 - Background: Transcranial magnetic stimulation (TMS) can modulate transiently the physiological brain oscillations, e.g. the alpha rhythm. It has been hypothesized that this effect is not limited to the stimulated region but involves subcortical and distant cortical areas. Methods: We applied single pulse TMS to the primary motor cortex (M1) of healthy subjects to interfere the cortical oscillatory activity recorded by simultaneous EEG and calculated the cortico-cortical coherence and power in the alpha and beta band. To study the structural substrate of the functional connectivity we performed diffusion tensor imaging and fractional anisotropy analysis (FA). To capture the pathways involved we applied probabilistic tractography to reconstruct the entire network. Results: Suprathreshold TMS of M1 induced a consistent enhancement of interhemispheric cortico-cortical alpha band coherence that lasted ca. 175 ms. after the pulse has been applied. The changes were confined to the interhemispheric central EEG electrodes (i.e. C3-C4). There were no consistent changes in the beta band. Power analysis revealed a longer lasting increase in the beta band after TMS pulses. A cluster in the contralateral thalamus showed a linear relationship between regional FA and TMS induced change in alpha band coherence. Probabilistic tractography presents the transcallosal and the contralateral thalamocortical pathways as essential for the observed oscillatory synchronisation. Conclusion: TMS induces an enhancement of oscillatory interaction between corresponding central regions of both hemispheres in the alpha band. The contralateral thalamus, transcallosal fibres and the contralateral thalamocortical pathways may constitute critical brain structures mediating the TMS induced change in oscillatory coupling.

AB - Background: Transcranial magnetic stimulation (TMS) can modulate transiently the physiological brain oscillations, e.g. the alpha rhythm. It has been hypothesized that this effect is not limited to the stimulated region but involves subcortical and distant cortical areas. Methods: We applied single pulse TMS to the primary motor cortex (M1) of healthy subjects to interfere the cortical oscillatory activity recorded by simultaneous EEG and calculated the cortico-cortical coherence and power in the alpha and beta band. To study the structural substrate of the functional connectivity we performed diffusion tensor imaging and fractional anisotropy analysis (FA). To capture the pathways involved we applied probabilistic tractography to reconstruct the entire network. Results: Suprathreshold TMS of M1 induced a consistent enhancement of interhemispheric cortico-cortical alpha band coherence that lasted ca. 175 ms. after the pulse has been applied. The changes were confined to the interhemispheric central EEG electrodes (i.e. C3-C4). There were no consistent changes in the beta band. Power analysis revealed a longer lasting increase in the beta band after TMS pulses. A cluster in the contralateral thalamus showed a linear relationship between regional FA and TMS induced change in alpha band coherence. Probabilistic tractography presents the transcallosal and the contralateral thalamocortical pathways as essential for the observed oscillatory synchronisation. Conclusion: TMS induces an enhancement of oscillatory interaction between corresponding central regions of both hemispheres in the alpha band. The contralateral thalamus, transcallosal fibres and the contralateral thalamocortical pathways may constitute critical brain structures mediating the TMS induced change in oscillatory coupling.

U2 - 10.1016/j.brs.2012.03.014

DO - 10.1016/j.brs.2012.03.014

M3 - Journal article

C2 - 22537867

SN - 1935-861X

VL - 6

SP - 138

EP - 146

JO - Brain Stimulation

JF - Brain Stimulation

IS - 2

ER -