随意運動 Voluntary movements
P3-1-125 発揮張力に関する視覚フィードバックゲインの予測不可能な増減によって引き起こされる皮質-筋コヒーレンスの変化 Unpredictable alteration in visual feedback gain of exerted force during intermittent isometric muscle contraction modulates corticomuscular coherence ○小野瀬冬馬1, 牛山潤一1,2, 春日翔子3, 牛場潤一2,3 ○Toma Onose1, Junichi Ushiyama1,2, Shoko Kasuga3, Junichi Ushiba2,3 慶應大院・理・基礎理工1, 慶應大・医・リハ2, 慶應大・理・生命情報3 Grad Sch Fund Sci and Tech, Keio Univ, Kanagawa1, Dept Rehab Med, Keio Univ Sch Med, Tokyo2, Dept Biosci and Informat, Fac Sci and Tech, Keio Univ, Kanagawa3 Sensorimotor recalibration is modulation of the sensorimotor integration process, in order to adapt to changes of external/internal environments of our body. Corticomuscular coherence has been suggested as a potential biomarker representing such a recalibration process, but it is unclear whether coherence is actually associated with updating process of correspondence relationship between sensory input and motor output. Therefore in this study, we tested modulation of coherence with unpredictable alterations of visual force feedback gain during isometric contraction, and evaluated its contribution to sensorimotor recalibration along with changes of environment. Ten healthy participants (22-28 yrs) performed intermittent force tracking tasks with ankle dorsiflexion. Electroencephalogram (EEG) over the sensorimotor cortex and electromyogram (EMG) of the tibialis anterior muscle were recorded to calculate EEG-EMG coherence. The exerted force was visually fed back to the subjects, and the gain of the feedback was sometimes unpredictably increased or decreased. The magnitude of coherence was significantly higher in the increased gain condition than in the decreased or the unchanged gain condition. This result suggests that the feedback control process to reduce errors caused by excess force output is mediated by EEG-EMG coherence. In addition, we classified trials into three groups, based on the error amplitude between target force and initially exerted force in each trial. Only in the increased gain condition, the magnitude of EEG-EMG coherence was significantly higher in large error trials than in small error trials. It suggests that the larger amount of recalibration may induce more synchronized activity in EEG and EMG. Current findings imply that the update of sensorimotor feedback controller during sensorimotor recalibration is mediated by oscillatory coupling between the sensorimotor cortex and the muscle, which is reflected in high corticomuscular coherence.	P3-1-126 静的随意筋収縮中の皮質－筋コヒーレンス強度を規定する脊髄内神経機構 A spinal factor determining individual magnitude of corticomuscular coherence during tonic isometric voluntary contraction ○牛山潤一1,2, 松谷良佑2, 里宇明元1, 牛場潤一1,3 ○Junichi Ushiyama1,2, Ryosuke Matsuya2, Meigen Liu1, Junichi Ushiba1,3 慶應義塾大学医学部　リハビリテーション医学教室1, 慶應義塾大学大学院理工学研究科2, 慶應義塾大学理工学部生命情報学科3 Dept Rehab Med, Keio Univ Sch Med, Tokyo1, Grad Sch Fund Sci and Tech, Keio Univ, Kanagawa2, Dept Biosci and Informat, Fac Sci and Tech, Keio Univ, Kanagawa3 Oscillatory neural activity of the sensorimotor cortex has been reported to show coherence with muscular activity of the contralateral limb muscles within the 15-35 Hz frequency band (β-band) during weak to moderate intensity of tonic isometric voluntary contraction. We have recently reported that there is a great variance in the magnitude of corticomuscular coherence among individuals, and that subjects with greater coherence show more prominent oscillatory muscular activity, which would regulate the motor performance. However, potential mechanisms underlying such a between-subject variance in the magnitude of corticomuscular coherence have not been clarified yet. In the present study, we focused on Renshaw cell recurrent inhibition, and examined whether the neural circuit at the spinal level works as a factor determining individual magnitude of corticomuscular coherence. Twelve healthy young participants (aged 22-28 yrs; seven males and five females) performed 45 tonic isometric voluntary plantarflexions at 15% of maximal effort lasting 7 s each. During the task, we recorded the electroencephalogram (EEG) signals over the sensorimotor cortex and electromyogram (EMG) signals from the soleus muscle, and calculated their coherence. Further, by using the evoked EMG technique, we also assessed the extent of recurrent inhibition during the muscle contractions. As results, the magnitude of EEG-EMG coherence greatly varied among individuals (range, 0.048-0.357), as we previously reported, and showed a significant negative correlation with the extent of recurrent inhibition (p<0.05). These data suggest that during tonic isometric voluntary contraction, the Renshaw cell recurrent inhibition works as a "neural filter" at the spinal level, and the difference in its effect among participants is a factor determining individual magnitude of β-band corticomuscular coupling and related oscillatory muscular activity.
P3-1-127 遅延適応における運動準備電位 Readiness potential in lag adaptation ○蔡暢1, 小川健二2,3, 今水寛1,2 ○Chang Cai1, Kenji Ogawa2,3, Hiroshi Imamizu1,2 情報通信研・脳情報通信融合研究センター1, ATR認知機構研2, 日本学術振興会3 NICT Center for Information & Neural Networks, Osaka1, ATR Cognitive Mechanisms Labs2, Japan Society for the Promotion of Science (JSPS), Tokyo3 The relative timing of a motor-sensory event can be recalibrated after exposure to delayed visual feedback. Previous studies have investigated brain activity related to an illusory reversal of cause-effect order when the visual delay was removed after the recalibration (Stetson et al., 2006; Stekelenburg et al., 2011). What brain areas contribute to the recalibration process itself, however, still remains unexplored. We hypothesized that the onset of voluntary control signal in the motor system undergoes temporal recalibration whereas the early sensory system maintains veridical timing of visual events. We tested this hypothesis by measuring the onset of readiness potentials in delay and no-delay trials. FMRI and MEG experiments were involved in this study. Data were analyzed using Variational Bayesian Multimodal EncephaloGraphy (VBMEG). In fMRI experiment, subjects were asked to press a key voluntarily with their right middle finger and fixate on a flash as visual feedback. FMRI results served as prior in VBMEG analysis of MEG data. In MEG experiment, subjects were also asked to voluntarily press a key with their right middle finger and fixate on a LED feedback with no delay or 150ms delay. Temporal order judgment task was also used to estimate the adaptation. Eight subjects joined the experiments, and we could get enough data both in adaption and non-adaptation cases from four of them. Readiness potentials in the left premotor cortex showed a significant recalibration effect: compared to no-delay trials, there were late onsets in delay trials in case of the adaptation while there was less or no such late effect in case of the non-adaptation. By contrast, we did not find such recalibration effect in evoked potentials in the early visual cortex. These results suggest that the timing in motor system can be recalibrated in lag adaptation while stable timing representation in the early sensory system.	P3-1-128 異なる課題要求における対象物の把持位置: 中心視野条件と周辺視野条件 Grasp points of objects in the central and peripheral visual field conditions ○片山正純1, 福井優太1 ○Masazumi Katayama1, Yuta Fukui1 福井大院・工・知能システム工学専攻1 Dept Human and Artificial Intelligent Systems, University of Fukui, Fukui1 In this study, we investigate grasp points of objects that vary according to each task demand of two tasks: the lift-up task (LT) that picks up an object and the pinch task (PT) that does not lift it from a table. We reported that the grasp points of PT are different from those of LT (Fujita, Katayama, 2007), although both of LT and PT are classified as a similar action task. Thus, we found that the grasp point computation in the human brain is selected by each task demand of the tasks. From the hypothesis of Goodale and Milner (1992), there is a possibility that the ventral and dorsal streams of visual processing contribute the computation of PT and LT, respectively. In addition, from anatomical findings, the central and peripheral vision systems are mainly related to the ventral and dorsal streams, respectively. Thus, we propose the hypothesis that the central and peripheral vision systems are related to the grasp point computation of LT and PT, respectively. In order to validate the plausibility of this hypothesis, we investigated grasp points of LT and PT under the normal vision condition (NVC), the central vision condition (CVC) that the visual field was restricted by the goggle that the peripheral visual field is invisible, and the peripheral vision condition (PVC) that executes each task while gazing a fixation point. In the experiments, ten objects (five shapes x two size) were used in CVC and PVC, three visual angles (±3 deg, ±6 deg, ±8 deg) were used in CVC and four fixation points arranged at the upper and lower sides of an object were used in PVC. As a result, both the grasp points of LT and PT in CVC were the same as the case of PT in NVC, and moreover both of the grasp points in PVC were the same as the case of LT in NVC. These results show the plausibility of the hypothesis. One possible reason why the grasp points of LT and PT are different is the difference of visual mechanisms related to each grasp point computation for LT and PT.
P3-1-129 異なる課題要求における対象物の把持位置: 慣れた把持と不慣れな把持 Grasp points of objects that vary according to skillfulness of action ○林侑平1, 片山正純1 ○Yuhei Hayashi1, Masazumi Katayama1 福井大学大学院 工学研究科 知能システム工学専攻1 Dept Human and Artificial Intelligent Systems, University of Fukui, Fukui1 In this study, we investigate grasp points of objects that vary according to task demands. We previously reported that grasp points of the vision task (VT) that judges visually are different from those of the lift-up task (LT) that picks up an object and moreover grasp points of VT are the same as those of the pinch task (PT) that does not lift it up from a table (Fujita, Katayama, 2007). Thus, we found that there are at least two types of grasp point computation in the human brain. The computation is selected by each task demand of the three tasks. In addition, from Gonzalez's results (2008), there is a possibility that the computation is also switched by the level of skillfulness for grasping objects with skillful and awkward grips. From this point of view, in order to investigate brain mechanism of the grasp point computation, we measured grasp points of skillful and awkward grips for the action tasks (LT and PT) and VT. In the experiments, a skillful grip was the precision grip of the thumb and index finger of the dominant hand and awkward grips were the precision grips of the thumb and annular fingers of the dominant and nondominant hand. As a result, we confirmed that grasp points of LT of the awkward grips were the same as those of VT and PT of the skillful grips and grasp points of PT of the awkward grips were the same as those of VT and PT of the skillful grips. Moreover, after repeatedly picking up a cubic object, that did not use in the above experiments, with the awkward grips, we measured grasp points of LT of the awkward grips. The grasp points became the same as those of LT of the skillful grips. These results show that the grasp point computation depends on the level of skillfulness for action. In addition, our results indicate that the dorsal visual stream contributes the grasp point computation for skillful grasping movements and the ventral visual stream contributes the computation of awkward grasping movements.	P3-1-130 手指随意運動中断動作に対する単発経頭蓋磁気刺激による干渉 Inhibitory interference in voluntary motor abandonment of finger movement by single-pulse transcranial magnetic stimulation ○常盤達司1, 石丸尚之1, 福田浩士1, 樋脇治1 ○Tatsuji Tokiwa1, Naoyuki Ishimaru1, Hiroshi Fukuda1, Osamu Hiwaki1 広島市立大学大学院　創造科学専攻　生体理工学研究室1 Grad. Sch. of Info. Sci., Hiroshima City Univ., Hiroshima1 In this study, a cortical dynamic motor control of finger movement was investigated with transcranial magnetic stimulation (TMS). A point-to-point reaching movement of the right index-finger was conducted.The position of the finger-tip measured with a motion-capture system was shown to the subject with a PC monitor. The starting time of the movement was indicated with the clock making one revolution for 4 s. The time the clock hand passed the 9 o'clock position was defined as a go-signal. In the series of trials, red LED illumination was randomly indicated as a stop-signal 100ms before the go-signal. In both go-trials and stop-trials, TMS with a round coil on the subject's head was conducted at -400, -350, -300, -250, -200, -150, -100, -50, 0, 50 ms from the go-signal. Sham-TMS trials with a click sound of TMS without the brain stimulation were also conducted in the series of trials. In the sham-TMS trials with the stop-signal, the subject was able to prevent the finger movement. However, the finger involuntarily moved in the stop trials with TMS conducted at 150ms before the start-signal. We also measured brain potentials in the sham-TMS and TMS trials. The potential at Fz electrode showed a large positive peak at 455 ms after the go-signal in the sham-TMS trials of the stop-trials, whereas the amplitude of the potential at the same latency was attenuated in the TMS trials of the stop-trials. These results indicated that the single-pulse TMS applied around the stop-signal in the stop-trial of the reaching finger movement interfered in the function of the medial frontal cortex for voluntary motor abandonment.
P3-1-131 脊髄損傷後の回復過程における腹側線条体の役割 Role of the ventral striatum for the motor recovery after spinal cord injury ○澤田真寛1,3, 尾上浩隆2, 加藤健治1,4, 伊佐正1,4, 西村幸男1,4 ○Masahiro Sawada1,3, Hirotaka Onoe2, Kenji Kato1,4, Tadashi Isa1,4, Yukio Nishimura1,4 生理学研究所 認知行動発達機構研究部門1, 理化学研究所 分子イメージング科学研究センター2, 京都大学大学院医学部 脳神経外科学3, 総合研究大学院大学4, JST-PREST5 Dept Dev Physiol, Natl Inst Physiol Sci, Okazaki, Japan1, Cent Mol Imaging Sci, RIKEN, Kobe, Japan2, Dept of Neurosurgery, Grad Sch of Kyoto Univ, Kyoto, Japan3, Graduate Univ for Adv Stu, SOKENDAI, Hayama, Japan4, JST-PRESTO, Tokyo, Japan5 Depression is a common psychological problem in individuals with neuronal damage. Therefore, motivation is a key issue for functional recovery. However the neuronal mechanism underlying such psychological effect on functional recovery remains unclear. Recently, we found that the ventral stratum, a center for processing motivation, increased the activity in association with that of the primary motor cortex during the recovery from the spinal cord injury in monkeys. To clarify the causal relationship between functional recovery and activity of the ventral stratum, we performed reversible pharmacological blockade of the ventral stratum throughout the preoperative stage and recovery course and observed the finger dexterity. We made a unilateral lesion of the corticospinal tract at the mid-cervical spinal segment in two rhesus monkeys. Precision grip recovered 6-7 weeks after the lesion in monkey P. We performed unilateral focal inactivation of striatum by microinjections of muscimol, GABAA receptor agonist (1µl /site, 5µg/µl), at various recovery stages. In monkey P who showed slow recovery, the inactivation of stratum significantly impaired finger dexterity throughout all recovery stage. Preoperative inactivation showed minor effect on finger dexterity in the monkey. Inactivation did not affect upper limb movement of ipsilateral side to the inactivation. The injection of saline (1µl /site) had no effect. In monkey D who showed very mild deficit in finger dexterity after lesion, the inactivation induced slowing in the precision grip task only at the postoperative 1 month. The histological reconstruction showed the inactivated area extended to the nucleus accumbense and ventral pallidum which have been described to be involved in the processing of motivation and emotion. These results suggest that the ventral stratum plays an important role in maintenance of the functional recovery of finger dexterity after spinal cord injury	P3-1-132 ドーパミンD1受容体の減少は運動量の減少を引き起こす Suppression of dopamine D1 receptor expression cause decreased motor activity ○佐藤朝子1, 新井慧1, 前島純1, 笹岡俊邦1 ○Asako Sato1, Satoshi Arai1, Jun Maeshima1, Toshikuni Sasaoka1 北里大学・医学部・実験動物学1 Lab Animal Sci, Kitasato Univ Sch of Med, Kanagawa, Japan1 Dopamine controls a wide variety of behavior related to motor activity, cognition, motivation and reward. Dopamine D1 (D1R) and D2 receptors (D2R) are found at high levels in the striatal projection neurons, which have important roles in motor control. It is reported that conventional D1R knockout (KO) mice are hyperactive although D1R theoretically promotes motor activity. It is suspected that potential developmental adaptation could cause hyperactive phenotype in D1R KO mice. To circumvent developmental adaptation, we generated a transgenic mice harboring tetracycline-regulated expression of D1R gene with D1R KO background (D1R -/-;Tg +). In the absence of Dox, a tetracycline antibiotic, the transgenic mice showed constitutive strong expression of D1R under the control of D1R promoter, which rescued hyperactive phenotype in D1R KO mice. We suppressed the D1R expression in adult D1R -/-;Tg + mice and monitored home cage activity to clarify the role of D1R. When Dox was administered for up to 5 weeks, D1R expression was decreased to levels undetectable by western blotting. Simultaneously, home cage activity of the D1R -/-;Tg + mice was significantly decreased. These results disagree with the hyperactive phenotype in conventional D1R KO mice but agree with the theory that D1R promotes motor activity. It is demonstrated that D1R is required to maintain normal activity and suggested that the D1R -/-;Tg + mice are useful to investigate the role of D1R in adult with less influence of developmental adaptation.

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