OBJECTIVE: To investigate the after-effects of theta burst TMS (TBS) on cortico-muscular synchronization, and on cortico-spinal excitability, in humans. METHODS: We studied 10 healthy subjects using a continuous paradigm of TBS (cTBS), i.e. 600 pulses in 40s. Before and after the cTBS, coherence function was computed as a measure of cortico-muscular synchronization by recording electroencephalogram (EEG) from 19 scalp sites and electromyogram (EMG) from right first dorsal interosseous (FDI) muscle during the isometric contraction. In a separate experiment, motor-evoked potentials (MEPs) in response to single TMS pulses were recorded from the FDI muscle before and after the cTBS, to measure cortico-spinal excitability. RESULTS: When the cTBS was applied over the left primary motor cortex (M1), the beta-band cortico-muscular coherence for the C3 scalp site, as well as the MEP amplitude significantly decreased in 30-60 min, and then recovered to the original levels in 90-120 min. Neither sham stimulation nor cTBS applied over 2 cm posterior to M1 produced significant effects. CONCLUSIONS: cTBS-over-M1 can inhibit the cortico-muscular synchronization in parallel with the decline of cortico-spinal excitability. SIGNIFICANCE: Our results provide the first evidence that TBS can efficiently alter the functional cortico-muscular coupling in humans.
OBJECTIVE: To investigate the after-effects of theta burst TMS (TBS) on cortico-muscular synchronization, and on cortico-spinal excitability, in humans. METHODS: We studied 10 healthy subjects using a continuous paradigm of TBS (cTBS), i.e. 600 pulses in 40s. Before and after the cTBS, coherence function was computed as a measure of cortico-muscular synchronization by recording electroencephalogram (EEG) from 19 scalp sites and electromyogram (EMG) from right first dorsal interosseous (FDI) muscle during the isometric contraction. In a separate experiment, motor-evoked potentials (MEPs) in response to single TMS pulses were recorded from the FDI muscle before and after the cTBS, to measure cortico-spinal excitability. RESULTS: When the cTBS was applied over the left primary motor cortex (M1), the beta-band cortico-muscular coherence for the C3 scalp site, as well as the MEP amplitude significantly decreased in 30-60 min, and then recovered to the original levels in 90-120 min. Neither sham stimulation nor cTBS applied over 2 cm posterior to M1 produced significant effects. CONCLUSIONS:cTBS-over-M1 can inhibit the cortico-muscular synchronization in parallel with the decline of cortico-spinal excitability. SIGNIFICANCE: Our results provide the first evidence that TBS can efficiently alter the functional cortico-muscular coupling in humans.
Authors: Odysseas Papazachariadis; Vittorio Dante; Paul F M J Verschure; Paolo Del Giudice; Stefano Ferraina Journal: PLoS One Date: 2014-11-10 Impact factor: 3.240