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Fukushima-shi, Japan

Watanabe T.,University of Tokyo | Hanajima R.,University of Tokyo | Shirota Y.,University of Tokyo | Shirota Y.,Japan Society for the Promotion of Science | And 10 more authors.
Human Brain Mapping | Year: 2014

Several recent studies using functional magnetic resonance imaging (fMRI) have shown that repetitive transcranial magnetic stimulation (rTMS) affects not only brain activity in stimulated regions but also resting-state functional connectivity (RSFC) between the stimulated region and other remote regions. However, these studies have only demonstrated an effect of either excitatory or inhibitory rTMS on RSFC, and have not clearly shown the bidirectional effects of both types of rTMS. Here, we addressed this issue by performing excitatory and inhibitory quadripulse TMS (QPS), which is considered to exert relatively large and long-lasting effects on cortical excitability. We found that excitatory rTMS (QPS with interstimulus intervals of 5 ms) decreased interhemispheric RSFC between bilateral primary motor cortices, whereas inhibitory rTMS (QPS with interstimulus intervals of 50 ms) increased interhemispheric RSFC. The magnitude of these effects on RSFC was significantly correlated with that of rTMS-induced effects on motor evoked potential from the corresponding muscle. The bidirectional effects of QPS were also observed in the stimulation over prefrontal and parietal association areas. These findings provide evidence for the robust bidirectional effects of excitatory and inhibitory rTMSs on RSFC, and raise a possibility that QPS can be a powerful tool to modulate RSFC. © 2013 Wiley Periodicals, Inc. Source

Matsumoto H.,University of Tokyo | Terao Y.,University of Tokyo | Furubayashi T.,University of Tokyo | Yugeta A.,University of Tokyo | And 5 more authors.
Basal Ganglia | Year: 2012

For Parkinson's disease (PD), we have reported that small saccades restrict visual scanning (Matsumoto H, Terao Y, Furubayashi T et al. Small saccades restrict visual scanning area in Parkinson's disease. Mov Disord 2011;26:1619-26), possibly resulting in the disturbances of visual attention in PD. However, it remains unknown why the saccade amplitude is reduced during visual scanning. The aim of this paper is to study whether the small saccade amplitude during visual scanning results from basal ganglia (BG) dysfunction. This study examined 18 PD patients. The saccade amplitude during viewing visual images was recorded. The saccade amplitude in oculomotor tasks, visually guided saccades (VGS) and memory-guided saccades (MGS) were also recorded. We analyzed the correlation between the saccade amplitude during visual scanning and the saccade amplitude during oculomotor tasks. The saccade amplitude during visual scanning was reduced compared to normal subjects. Similarly, the saccade amplitudes in both VGS and MGS were also reduced. However, the saccade amplitude during visual scanning always correlated with MGS amplitude, whereas it hardly related to VGS amplitude. Our results indicate that BG dysfunction might reduce the saccade amplitude during visual scanning in this disorder. © 2012 Elsevier GmbH. Source

Matsumoto H.,Red Cross | Matsumoto H.,University of Tokyo | Konoma Y.,Red Cross | Shimizu T.,Red Cross | And 8 more authors.
Muscle and Nerve | Year: 2012

Introduction: In this study we investigated the effects of aging on corticospinal tract conduction by measuring the corticoconus motor conduction time (CCCT). Methods: Motor evoked potentials were recorded from the right tibialis anterior muscle in 100 healthy volunteers. To activate the most proximal part of the cauda equina, magnetic stimulation was performed using a MATS coil over the L1 spinous process (L1-level latency). Transcranial magnetic stimulation of the motor cortex was also conducted (cortical latency). To obtain the CCCT, the L1-level latency was subtracted from the cortical latency. Results: Age was significantly correlated with L1-level latency, but it was not significantly correlated with CCCT. Conclusions: CCCT is the most direct indicator of corticospinal tract conduction, whereas L1-level latency reflects whole peripheral motor conduction. Central motor conduction was found to be relatively less affected by aging compared with peripheral motor conduction. © 2012 Wiley Periodicals, Inc. Source

Shirota Y.,University of Tokyo | Shirota Y.,Japan Society for the Promotion of Science | Hamada M.,University of Tokyo | Hamada M.,University College London | And 6 more authors.
Experimental Brain Research | Year: 2012

The supplementary motor area (SMA) is a secondary motor area that is involved in various complex hand movements. In animal studies, short latency and probably direct excitatory inputs from SMA to the primary motor cortex (M1) have been established. Although human imaging studies revealed functional connectivity between SMA and M1, its electrophysiological nature has been less studied. This study explored the connection between SMA and M1 in humans using a single-pulse transcranial magnetic stimulation (TMS) over SMA. First, TMS over SMA did not alter the corticospinal tract excitability measured by the size of motor evoked potential elicited by single-pulse TMS over M1. Next, we measured short-interval intracortical facilitation (SICF), which reflects the function of a facilitatory circuit within M1, with or without a singlepulse TMS over SMA. When the intensity of the second pulse in the SICF paradigm (S2) was as weak as 1.0 active motor threshold for a hand muscle, SMA stimulation significantly enhanced the SICF. Furthermore, this enhancement by SMA stimulation was spatially confined and had a limited time window. On the other hand, SMA stimulation did not alter short-interval intracortical inhibition or contralateralsilent period duration, which reflects the function of an inhibitory circuit mediated by gamma-aminobutyricacid A (GABAA) or GABAB receptors, respectively. We conclude that a single-pulse TMS over SMA modulates a facilitatory circuit within M1. © Springer-Verlag 2012. Source

Groiss S.J.,Fukushima Medical University | Mochizuki H.,Fukushima Medical University | Furubayashi T.,Fukushima Medical University | Furubayashi T.,Tohoku Bunka Gakuen University | And 5 more authors.
Brain Stimulation | Year: 2013

Background: Imaging studies investigating repetitive transcranial magnetic stimulation (rTMS) mediated hemodynamic consequences revealed inconsistent results, mainly due to differences in rTMS parameters and technical difficulties with simultaneous recordings during rTMS. Objective/Hypothesis: Quadri-pulse rTMS (QPS) induces bidirectional long-term plasticity of the human primary motor cortex (M1). To evaluate its on-line effects, near infrared spectroscopy (NIRS) recordings were performed during QPS. We hypothesized that on-line effects during QPS are different from long-term aftereffects. Methods: Using a novel TMS - on-line multi-channel NIRS setup we recorded hemoglobin concentration [Hb] changes at the stimulated M1 and adjacent sensory-motor areas during QPS protocols inducing oppositely directed aftereffects (QPS-5: interstimulus interval (ISI) 5 ms, potentiation; QPS-50: ISI 50 ms, depression). In two experiments we studied NIRS changes during either single or repeated QPS bursts. Results: The repetitive QPS-5 bursts significantly decreased oxyhemoglobin concentration ([oxy-Hb]) in the ipsilateral M1. A single QPS-5 burst decreased [oxy-Hb] in the M1 and premotor cortex. QPS-50 induced no significant NIRS changes at any sites. Conclusions: QPS can significantly alter cortical hemodynamics depending on the stimulation frequency. While bidirectional long-term aftereffects of QPS reflect synaptic efficacy changes, unidirectional on-line effects during QPS may represent pure electrophysiological property changes within the cell membrane or synapse. Since neuronal postexcitatory inhibitory postsynaptic potentials typically peak within the first 10-20 ms, only pulses delivered at higher frequencies may lead to summation of the inhibitory effects, resulting in [oxy-Hb] decrease only after QPS-5. Our new TMS-NIRS setup may be valuable to investigate TMS induced neurovascular coupling mechanisms in humans. © 2013 Elsevier Inc. All rights reserved. Source

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