Details of a Researcher - SUGAWARA Kazuhiro

Papers - SUGAWARA Kazuhiro

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Change-Driven M100 Component in the Bilateral Secondary Somatosensory Cortex: A Magnetoencephalographic Study.

Yamashiro K, Sato D, Onishi H, Sugawara K, Otsuru N, Kirimoto H, Nakazawa S, Yamazaki Y, Shirozu H, Maruyama A

Brain topography 32 ( 3 ) 435 - 444 2019.05 [Refereed] [International journal]

Our previous demonstration that the M100 somatosensory evoked magnetic field (SEF) has a similar temporal profile, dipole orientation and source location whether induced by activation (ON-M100) or deactivation (OFF-M100) of electrical stimulation suggests a common cortical system to detect sensory change. While we have not recorded such change-driven components earlier than M100 using electrical stimulation, clear M50 responses were reported using both ON and OFF mechanical stimulation (Onishi et al. in Clin Neurophysiol 121:588-593, 2010). To examine the significance of M50 and M100 in reflecting the detection of somatosensory changes, we recorded these waveforms in 12 healthy subjects (9 males and 3 females) by magnetoencephalography in response to mechanical stimulation from a piezoelectric actuator. Onset and offset (ON and OFF) stimuli were randomly presented with three preceding steady state (PSS) durations (0.5, 1.5 and 3 s) in one consecutive session. Results revealed that (i) onset and offset somatosensory events elicited clear M50 and M100 components; (ii) M50 and M100 components had distinct origins, with M50 localised to the contralateral primary somatosensory cortex (cS1) and M100 to the bilateral secondary somatosensory cortex (iS2, cS2); and (iii) the amplitude of M50 in cS1 was independent of the PSS durations, whereas that of M100 in S2 was dependent on the PSS durations for both ON and OFF events. These findings suggest that the M50 amplitude in cS1 reflects the number of activated mechanoreceptors during Onset and Offset, whereas the M100 amplitude in S2 reflects change detection based on sensory memory for Onset and Offset stimuli at least in part. We demonstrated that the M50 in cS1 and M100 in S2 plays different roles in the change detection system in somatosensory modality.

DOI PubMed

Effect of muscle contraction strength on gating effect —An MEG study—

Sugawara Kazuhiro

JAPANESE JOURNAL OF PHYSICAL THERAPY FUNDAMENTALS 21 ( 1 ) 63 - 68 2018 [Refereed]

Authorship： Lead author , Corresponding author

Electrical Stimulation of Denervated Rat Skeletal Muscle Ameliorates Bone Fragility and Muscle Loss in Early-Stage Disuse Musculoskeletal Atrophy.

Tamaki H, Yotani K, Ogita F, Hayao K, Nakagawa K, Sugawara K, Kirimoto H, Onishi H, Kasuga N, Yamamoto N

Calcif Tissue Int Apr; 100 ( 4 ) 420 - 430 2017.02 [Refereed]

Cortical oxyhemoglobin elevation persists after moderate-intensity cycling exercise: A near-infrared spectroscopy study

Tsubaki A,, Takehara N, Sato D, Morishita S, Tokunaga Y, Sugawara K, Kojima S, Tamaki H, Yamazaki Y, Onishi H

Advances in Experimental Medicine and Biology ( Springer New York LLC ) 977 261 - 268 2017 [Refereed]

Near-infrared spectroscopy (NIRS) can measure cortical activity during gross motor tasks based on the cerebral hemodynamic response. Although some reports suggest that cycling exercise improves cortical oxygenation, its after-effects are unknown. We examined the after-effects of low- and moderate-intensity cycling exercise on cortical oxygenation. Ten healthy volunteers (mean age 21.3 ± 0.7 years 4 women) underwent cycle ergometer exercise at 30% or 50% of VO2peak for 20 min, followed by an 8-min post-exercise rest (PER). O2Hb levels of the supplementary motor area (SMA) and sensorimotor cortex (SMC) were recorded using a near-infrared spectroscopy system. Skin blood flow (SBF) and mean arterial pressure (MAP) were continuously measured. The peak values of O2Hb between exercise and PER were compared. The O2Hb, SBF, and MAP increased in the exercise phase. SBF degraded over time, and MAP decreased immediately after exercise. The O2Hb decreased immediately and increased again in the PER. There were no significant differences between exercise and PER in the SMC in the 30% VO2peak experiment or in the SMA and SMC in the 50% VO2peak experiment. The O2Hb in the motor-related area was elevated during both exercise and PER especially in the 50% VO2peak experiment.

DOI PubMed

Effect of muscle contraction strength on gating of somatosensory magnetic fields

Sugawara K, Onishi H, Yamashiro K, Kotan S, Kojima S, Miyaguchi S, Tsubaki A, Kirimoto H, Tamaki H, Shirozu H, Kameyama S

Experimental Brain Research ( SPRINGER ) 234 ( 11 ) 3389 - 3398 2016.11 [Refereed]

Authorship： Lead author , Corresponding author

Afferent somatosensory information is modulated before the afferent input arrives at the primary somatosensory cortex during voluntary movement. The aim of the present study was to clarify the effect of muscular contraction strength on somatosensory evoked fields (SEFs) during voluntary movement. In addition, we examined the differences in gating between innervated and non-innervated muscle during contraction. We investigated the changes in gating effect by muscular contraction strength and innervated and non-innervated muscles in human using 306-channel magnetoencephalography. SEFs were recorded following the right median nerve stimulation in a resting condition and during isometric muscular contractions from 10 % electromyographic activity (EMG), 20 and 30 % EMG of the right extensor indicis muscle and abductor pollicis brevis muscle. Our results showed that the equivalent current dipole (ECD) strength for P35m decreased with increasing strength of muscular contraction of the right abductor pollicis brevis muscle. However, changes were observed only at 30 % EMG contraction level of the right extensor indicis muscle, which was not innervated by the median nerve. There were no significant changes in the peak latencies and ECD locations of each component in all conditions. The ECD strength did not differ significantly for N20m and P60m regardless of the strength of muscular contraction and innervation. Therefore, we suggest that the gating of SEF waveforms following peripheral nerve stimulation was affected by the strength of muscular contraction and innervation of the contracting muscle.

DOI

Effect of Range and Angular Velocity of Passive Movement on Somatosensory Evoked Magnetic Fields

Sugawara K, Onishi H, Yamashiro K, Kojima S, Miyaguchi S, Kotan S, Tsubaki A, Kirimoto H, Tamaki H, Shirozu H, Kameyama S

Brain Topography ( SPRINGER ) 29 ( 5 ) 693 - 703 2016.09 [Refereed]

Authorship： Lead author , Corresponding author

To clarify characteristics of each human somatosensory evoked field (SEF) component following passive movement (PM), PM1, PM2, and PM3, using high spatiotemporal resolution 306-channel magnetoencephalography and varying PM range and angular velocity. We recorded SEFs following PM under three conditions [normal range-normal velocity (NN), small range-normal velocity (SN), and small range-slow velocity (SS)] with changing movement range and angular velocity in 12 participants and calculated the amplitude, equivalent current dipole (ECD) location, and the ECD strength for each component. All components were observed in six participants, whereas only PM1 and PM3 in the other six. Clear response deflections at the ipsilateral hemisphere to PM side were observed in seven participants. PM1 amplitude was larger under NN and SN conditions, and mean ECD location for PM1 was at primary motor area. PM3 amplitude was larger under SN condition and mean ECD location for PM3 under SS condition was at primary somatosensory area. PM1 amplitude was dependent on the angular velocity of PM, suggesting that PM1 reflects afferent input from muscle spindle, whereas PM3 amplitude was dependent on the duration. The ECD for PM3 was located in the primary somatosensory cortex, suggesting that PM3 reflects cutaneous input. We confirmed the hypothesis for locally distinct generators and characteristics of each SEF component.

DOI

Inhibitory effect of intensity and interstimulus interval of conditioning stimuli on somatosensory evoked magnetic fields

Onishi H, Sugawara K, Yamashiro K, Sato D, Kirimoto H, Tamaki H, Shirozu H, Kameyama S

European Journal of Neuroscience ( WILEY-BLACKWELL ) 44 ( 4 ) 2104 - 2113 2016.08 [Refereed]

Magnetoencephalography (MEG) recordings were performed to investigate the inhibitory effects of conditioning stimuli with various types of interstimulus intervals (ISIs) or intensities on somatosensory evoked magnetic fields (SEFs) using a 306-ch whole-head MEG system. Twenty-three healthy volunteers participated in this study. Electrical stimuli were applied to the right median nerve at the wrist. Six pulse trains with ISIs of 500ms were presented in Experiment 1. A paired-pulse paradigm with three kinds of conditioning stimulus (CON) intensities, 500ms before the test stimulus (TS), was applied in Experiment 2. Finally, three CONs 500 or 1000ms before TS were presented in Experiment 3. Three main SEF deflections (N20m, P35m, and P60m) were observed, and the source activities of P35m and P60m significantly decreased after the 2nd pulse of a six pulse trains. These source activities also significantly decreased with increasing intensity of CON. In addition, these attenuations of source activities were affected by CON-CON or CON-TS intervals. These results indicated that the source activities were modulated by the intensity and ISIs of CONs. Furthermore, P35m after the stimulation were very sensitive to CONs; however, the attenuation of P60m after the stimulation lasted for a longer period than that of P35m. Our findings suggest that the conditioning stimulation had inhibitory effects on subsequent evoked cortical responses for more than 500ms. Our results also provide important clues about the nature of short-latency somatosensory responses in human studies.

DOI

Effect of Transcranial Direct Current Stimulation over the Primary Motor Cortex on Cerebral Blood Flow: A Time Course Study Using Near-infrared Spectroscopy

Takai H, Tsubaki A, Sugawara K, Miyaguchi S, Oyanagi K, Matsumoto M, Onishi H, Yamamoto N

Oxygen transport to tissue XXXVII ( SPRINGER ) 876 335 - 341 2016 [Refereed]

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that is applied during stroke rehabilitation. The purpose of this study was to examine diachronic intracranial hemodynamic changes using near-infrared spectroscopy (NIRS) during tDCS applied to the primary motor cortex (M1). Seven healthy volunteers were tested during real stimulation (anodal and cathodal) and during sham stimulation. Stimulation lasted 20 min and NIRS data were collected for about 23 min including the baseline. NIRS probe holders were positioned over the entire contralateral sensory motor area. Compared to the sham condition, both anodal and cathodal stimulation resulted in significantly lower oxyhemoglobin (O(2)Hb) concentrations in the contralateral premotor cortex (PMC), supplementary motor area (SMA), and M1 (p< 0.01). Particularly in the SMA, the O(2)Hb concentration during anodal stimulation was significantly lower than that during the sham condition (p< 0.01), while the O(2)Hb concentration during cathodal stimulation was lower than that during anodal stimulation (p< 0.01). In addition, in the primary sensory cortex, the O(2)Hb concentration during anodal stimulation was significantly higher than the concentrations during both cathodal stimulation and the sham condition (p< 0.05). The factor of time did not demonstrate significant differences. These results suggest that both anodal and cathodal tDCS cause widespread changes in cerebral blood flow, not only in the area immediately under the electrode, but also in other areas of the cortex.

DOI

Changes in Cortical Oxyhaemoglobin Signal During Low-Intensity Cycle Ergometer Activity: A Near-Infrared Spectroscopy Study

Tsubaki A, Takai H, Kojima S, Miyaguchi S, Sugawara K, Sato D, Tamaki H, Onishi H

Oxygen transport to tissue XXXVII ( SPRINGER ) 876 79 - 85 2016 [Refereed]

Near-infrared spectroscopy (NIRS) is a widely used non-invasive method for measuring human brain activation based on the cerebral hemodynamic response during gross motor tasks. However, systemic changes can influence measured NIRS signals. We aimed to determine and compare time-dependent changes in NIRS signal, skin blood flow (SBF), and mean arterial pressure (MAP) during low-intensity, constant, dynamic exercise. Nine healthy volunteers (22.1 +/- 1.7 years, 3 women) participated in this study. After a 4-min pre-exercise rest and a 4-min warm-up, they exercised on a bicycle ergometer at workloads corresponding to 30 % VO2 peak for 20 min. An 8-min rest period followed the exercise. Cortical oxyhaemoglobin signals (O(2)Hb) were recorded while subjects performed the exercise, using an NIRS system. Changes in SBF and MAP were also measured during exercise. O(2)Hb increased to 0.019 mM cm over 6 min of exercise, decreased slightly from 13 min towards the end of the exercise. SBF continued to increase over 16 min of the exercise period and thereafter decreased till the end of measurement. MAP fluctuated from -1.0 to 7.1 mmHg during the exercise. Pearson's correlation coefficients between SBF and O(2)Hb, and MAP and O(2)Hb differed in each time phase, from -0.365 to 0.713. During low-intensity, constant, dynamic exercise, the profile of changes in measurements of O(2)Hb, SBF, and MAP differed. These results suggested that it is necessary to confirm the relationship between O(2)Hb and systemic factors during motor tasks in order to detect cortical activation during gross motor tasks.

DOI

Correlation between the cerebral oxyhaemoglobin signal and physiological signals during cycling exercise: A near- infrared spectroscopy study

Tsubaki A, Takai H, Oyanagi K, Kojima S, Tokunaga Y, Miyaguchi S, Sugawara K, Sato D, Tamaki H, Onishi H

Advances in Experimental Medicine and Biology ( Springer New York LLC ) 923 ( 23 ) 159 - 166 2016 [Refereed]

Near-infrared spectroscopy (NIRS) is a widely used noninvasive method for measuring human brain activation based on the cerebral haemodynamic response. However, systemic changes can influence the signal’s parameters. Our study aimed to investigate the relationships between NIRS signals and skin blood flow (SBF) or blood pressure during dynamic movement. Nine healthy volunteers (mean age, 21.3 ± 0.7 years 6 women) participated in this study. The oxyhaemoglobin (O 2 Hb) signal, SBF, and mean arterial pressure (MAP) were measured while the volunteers performed multi-step incremental exercise on a bicycle ergometer, at workloads corresponding to 30, 50, and 70 % of peak oxygen consumption (VO2 peak) for 5 min. The Pearson’s correlation coefficients for the O2 Hb signal and SBF at 50 and 70 % VO2 peak were 0.877 (P < 0.01) and −0.707 (P < 0.01), respectively. The correlation coefficients for O2 Hb and MAP during warm-up, 30 % VO2 peak, and 50 % VO2 peak were 0.725 (P < 0.01), 0.472 (P < 0.01), and 0.939 (P < 0.01), respectively. Changes in the state of the cardiovascular system influenced O2 Hb signals positively during low and moderate-intensity exercise, whereas a negative relationship was observed during high-intensity exercise. These results suggest that the relationship between the O2 Hb signal and systemic changes is affected by exercise intensity.

DOI PubMed

Cortical magnetic activation following voluntary movement and several types of somatosensory stimulation.

Onishi H, Sugawara K, Yamashiro K, Sato D, Kirimoto H, Tamaki H, Shirozu H, Kameyama S

J Phys Fitness Sports Med 5 275 - 286 2016 [Refereed]

Skill-Specific Changes in Somatosensory Nogo Potentials in Baseball Players

Yamashiro K, Sato D, Onishi H, Sugawara K, Nakazawa S, Shimojo H, Akatsuka K, Nakata H, Maruyama A

Plos One ( PUBLIC LIBRARY SCIENCE ) 10 ( 11 ) doi: 10.1371/journal.pone.0142 2015.11 [Refereed]

Athletic training is known to induce neuroplastic alterations in specific somatosensory circuits, which are reflected by changes in somatosensory evoked potentials and event-related potentials. The aim of this study was to clarify whether specific athletic training also affects somatosensory Nogo potentials related to the inhibition of movements. The Nogo potentials were recorded at nine cortical electrode positions (Fz, Cz, Pz, F3, F4, C3, C4, P3 and P4) in 12 baseball players (baseball group) and in 12 athletes in sports, such as track and field events and swimming, that do not require response inhibition, such as batting for training or performance (sports group). The Nogo potentials and Go/Nogo reaction times (Go/Nogo RTs) were measured under a somatosensory Go/Nogo paradigm in which subjects were instructed to rapidly push a button in response to stimulus presentation. The Nogo potentials were obtained by subtracting the Go trial from the Nogo trial. The peak Nogo-N2 was significantly shorter in the baseball group than that in the sports group. In addition, the amplitude of Nogo-N2 in the frontal area was significantly larger in the baseball group than that in the sports group. There was a significant positive correlation between the latency of Nogo-N2 and Go/Nogo RT. Moreover, there were significant correlations between the Go/Nogo RT and both the amplitude of Nogo-N2 and Nogo-P3 (i.e., amplitude of the Nogo-potentials increases with shorter RT). Specific athletic training regimens may induce neuroplastic alterations in sensorimotor inhibitory processes.

DOI

Regional Changes in Cerebral Oxygenation Passive Movement Measured by Functional Near-infrared Spectroscopy

Sugawara K, Onishi H, Tsubaki A, Takai H, Tokunaga Y, Tamaki H

Frontiers in human neuroscience ( FRONTIERS MEDIA SA ) 9 ( 9 ) doi: 10.3389/fnhum.2015.00641 2015.11 [Refereed]

Authorship： Lead author , Corresponding author

The aim of this study is to investigate the influence of passive movement repetition frequency at 1.5-Hz and 1-Hz on changes in cerebral oxygenation and assess the temporal properties of these changes using functional near-infrared spectroscopy (fNIRS). No significant differences in systemic hemodynamics were observed between resting and passive movement phases for either 1.5-Hz or 1-Hz trial. Changes in cortical oxygenation as measured by fNIRS in bilateral supplementary motor cortex (SMC), left primary motor cortex (M1), left primary somatosensory cortex (Si), and left posterior association area (PM) during passive movement of the right index finger revealed greater cortical activity at only 1.5-Hz movement frequency. However, there were no significant differences in the time for peak oxyhemoglobin (oxyHb) among regions (bilateral SMC, 206.4 +/- 14.4s; left M1, 199.1 +/- 14.8s; left S1, 207.3 +/- 9.4s; left PM, 219.1 +/- 10.2s). Therefore, our results that passive movement above a specific frequency may be required to elicit a changed in cerebral oxygenation, and the times of peak Delta oxyHb did not differ significantly among measured regions.

DOI

Effect of electrical stimulation-induced muscle force and streptomycin treatment on muscle and trabecular bone mass in early-stage disuse musculoskeletal atrophy

Tamaki H, Yotani K, Ogita F, Sugawara K, Kirimto H, Onishi H, Kasuga N, Yamamoto N

Journal of musculoskeletal & neuronal interactions ( JMNI ) 15 ( 3 ) 270 - 278 2015.09 [Refereed]

Objectives: The aim was to determine whether daily muscle electrical stimulation (ES) and streptomycin treatment would have positive or negative effects on trabecular bone mass in disuse rats. Methods: Seven-week-old male F344 rats were randomly divided into five groups of eight animals each: an age-matched control group (CON); a sciatic denervation group (DN); a DN + direct electrical stimulation group (DN+ES); a DN + streptomycin treatment group (DN+SM); and a DN+ES+SM group. The tibialis anterior (TA) muscles in all ES groups were stimulated with 16mA at 10Hz for 30 min/day, six days/week, for one week. Bone volume and structure were evaluated using micro-CT, and histological examinations of the tibiae were performed. Results: Direct ES significantly reduced the disuse-induced trabecular bone loss. Osteoid thickness were also significantly greater in the ES groups than in the DN group. Micro CT and histomorphological parameters were significantly lower in the DN+ES+SM group than in the DN+ES group, while there were no significant differences between the DN and DN+SM groups. Conclusions: These results suggest that ES-induced muscle force reduced trabecular bone loss, and streptomycin treatment did not induce bone loss, but attenuated the effects of ES-induced muscle force on reducing the loss of disused bone.

Effects of cathodal transcranial direct current stimulation to primary somatosensory cortex on short- latency afferent inhibition

Kojima S, Onishi H, Miyaguchi S, Kotan S, Sugawara K, Kirimoto H, Tamaki H

Neuroreport ( LIPPINCOTT WILLIAMS & WILKINS ) 26 ( 11 ) 634 - 637 2015.08 [Refereed]

The aim of this study was to investigate the effects of cathodal transcranial direct current stimulation (tDCS) applied over the primary somatosensory cortex (S1) on short-interval afferent inhibition (SAI). Thirteen healthy individuals participated in this study. Cathodal tDCS was applied for 15min at 1mA over the left S1. Motor-evoked potentials (MEPs) were measured from the right first dorsal interosseous muscle in response to transcranial magnetic stimulation (TMS) of the left motor cortex before tDCS (pre), immediately after tDCS (immediately), and 15min after tDCS (post-15min). SAI was evaluated by measuring MEPs in response to TMS pulses applied 40ms after peripheral electrical stimulation of the index finger. For each measurement period (pre, immediately, and post-15min), MEP amplitude was significantly smaller when TMS followed index finger stimulation (SAI condition) than when TMS was delivered alone (single TMS) (P<0.01), indicating expression of SAI. The MEP ratio (MEP of SAI/MEP of single TMS) at post-15min was significantly larger than that of pre (P<0.05), indicating suppression of SAI. However, no significant difference was observed between pre and immediately, and immediately and post-15min. These results suggest that cathodal tDCS applied over the S1 causes a decrease in S1 excitability following peripheral electrical stimulation and cathodal tDCS applied over the S1 decreased the inhibitory effects of SAI. Copyright (C) 2015 Wolters Kluwer Health, Inc. All rights reserved.

DOI

Depression of corticomotor excitability after muscle fatigue induced by electrical stimulation and voluntary contraction

Kotan S, Kojima S, Miyaguchi S, Sugawara K, Onishi H

Frontiers in human neuroscience ( FRONTIERS RESEARCH FOUNDATION ) 9 ( 9 ) doi: 10.3389 2015.06 [Refereed]

In this study, we examined the effect of muscle fatigue induced by tetanic electrical stimulation (ES) and submaximal isometric contraction on corticomotor excitability. Experiments were performed in a cross over design. Motor evoked potentials (MEPs) were elicited by transcranial magnetic stimulation (TMS). Corticomotor excitability was recorded before and after thumb opposition muscle fatigue tasks, in which 10% of the maximal tension intensity was induced by tetanic ES or voluntary contraction (VC). The participants were 10 healthy individuals who performed each task for 10 min. Surface electrodes placed over the abductor pollicis brevis (APB) muscle recorded MEPs. F- and M-waves were elicited from APB by supramaximal ES of the median nerve. After the tetanic ES- and VC tasks, MEP amplitudes were significantly lower than before the task. However, F- and M-wave amplitudes remained unchanged. These findings suggest that corticospinal excitability is reduced by muscle fatigue as a result of intracortical inhibitory mechanisms. Our results also suggest that corticomotor excitability is reduced by muscle fatigue caused by both VC and tetanic ES.

DOI

Maximum Power During Vertical Jump and Isometric Knee Extension Torque Alter Mobility Performance: A Cross-Sectional Study of Healthy Individuals.

Tsubaki A, Kubo M, Kobayashi R, Jigami H, Sugawara K, Takahashi HE

PM R 29 doi: 10.1016 2015.04 [Refereed]

Effect of Changes in Stimulus Site on Activation of the Posterior Parietal Cortex

Yamashiro K, Sato D, Onishi H, Sugawara K, Nakazawa S, Kameyama S, Maruyama A

Brain Topography ( SPRINGER ) 28 ( 2 ) 261 - 268 2015.03 [Refereed]

A previous functional magnetic resonance imaging study elucidated the specific activity of the inferior parietal lobe (IPL) during a two-point discrimination task compared with that during an intensity discrimination task Akatsuka et al. (Neuroimage 40: 852-858, 2008). If the posterior parietal cortex (PPC), including IPL, is responsible for detecting changes in stimulus sites, PPC activity depends on the level of change at stimulus sites. The aim of this study was to clarify whether a particular site exists that could detect changes in stimulus sites using the oddball paradigm. Somatosensory-evoked magnetic fields were recorded in 10 right-handed subjects. Three oddball conditions were performed by all subjects, with the probability of deviant and standard stimuli being 20 and 80 %, respectively, under all three conditions. Deviant stimuli were always presented to the second digit of the hand and standard stimuli were presented to the first (small deviance: SD) and fifth digits (medium deviance: MD) of the hand and the first digit of the toe (large deviance: LD). Inter-stimulus intervals were set at 500 ms. A brain electrical source analysis showed that activities of areas 1 and 3b elicited by the deviant stimuli were not significantly different among the three conditions. In contrast, PPC activity was significantly greater for LD than for SD and MD. PPC activity tended to increase with greater deviance at stimulus sites, but activities of areas 1 and 3b did not differ. These findings suggest that PPC may have a functional role in automatic change detection systems with regard to deviance of stimulus sites.

DOI

Time Course of Change in Movement Structure During Learning of Goal-Directed Movement

Suzuki M, Kirimoto H, Sugawara K, Kasahara Y, Kawaguchi T, Ishizaka I, Yamada S, Matsunaga A, Fukuda M, Onishi H

Journal of medical and biological engineering ( SPRINGER HEIDELBERG ) 35 ( 1 ) 113 - 124 2015.02 [Refereed]

Primary and secondary submovements are important in human movements. The purpose of this study was to examine the time course of changes in kinematics and electromyography (EMG) parameters for primary and secondary submovements associated with the learning of a goal-directed aiming movement task. The subjects comprised 9 neurologically normal adults. They were instructed to make horizontal planar movements of elbow flexion that were both fast and accurate. The learning session comprised 20 blocks of 10 movements. Our research found that the kinematics- and EMG-related parameters of the antagonistic triceps brachii muscle gradually changed over the course of the learning period and reached a plateau that fitted an exponential function. However, the EMG parameters of the agonistic biceps brachii muscle did not markedly change. Moreover, the kinematics- and EMG-related parameters for the primary and secondary submovements varied at different rates during the motor learning. Our findings may facilitate the understanding of the learning of a goal-directed aiming movement in sports and rehabilitation settings.

DOI

The effect of anodal transcranial direct current stimulation over the primary motor or somatosensory cortices on somatosensory evoked magnetic fields

Kazuhiro Sugawara, Hideaki Onishi, Koya Yamashiro, Sho Kojima, Shota Miyaguchi, Hikari Kirimoto, Atsuhiro Tsubaki, Hiroyuki Tamaki, Hiroshi Shirozu, Shigeki Kameyama

CLINICAL NEUROPHYSIOLOGY ( ELSEVIER IRELAND LTD ) 126 ( 1 ) 60 - 67 2015.01 [Refereed]

Objectives: The purpose of this study was to investigate the effect of anodal transcranial direct-current stimulation (tDCS) applied over the primary motor (M1) or the primary somatosensory (S1) cortices on somatosensory evoked magnetic fields (SEFs) following median nerve stimulation. Methods: Anodal tDCS was applied for 15 min on the left motor or somatosensory cortices at 1 mA. SEFs were recorded following right median nerve stimulation using a magnetoencephalography (MEG) system before and after the application of tDCS. SEFs was measured and compared before and after tDCS was applied over M1 or S1. Results: The source strengths for the P35m and P60m increased after tDCS was applied over M1 and that for the P60m increased after tDCS was applied over S1. The mean equivalent current dipole (ECD) location for the P35m was located significantly anterior to that of the N20m, but only during post 1 (10-20 min after tDCS was applied over M1). Conclusion: Our results indicated that the anodal tDCS applied over M1 affected the P35m and P60m sources on SEF components, while that applied over S1 influenced the P60m source. Significance: We demonstrated anodal tDCS applied over M1 or S1 can modulate somatosensory processing and components of SEFs, confirming the hypothesis for locally distinct generators of the P35m and P60m sources. (C) 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

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