感覚運動制御/学習1
Sensorimotor control/learning 1
O1-8-1-1
注意欠陥多動性障害児におけるサッカード眼球運動異常に関する報告
Abnormal saccade initiation in ADHD children

○喜多村祐里1, 渡邊雅之2, 松尾有華1, 毛利育子3, 小橋昌司4, 谷池雅子3, 小林康5
○Yuri Kitamura1, Masayuki Watanabe2, Yuka Matsuo1, Ikuko Mohri3, Syoji Kobashi4, Masako Taniike3, Yasushi Kobayashi5
大阪大学大学院 医学系研究科 社会環境医学1, クィーンズ大学 生体医学/分子生物学2, 大阪大学連合大学院 小児発達学研究科 子どものこころの分子統御機構研究センター3, 兵庫県立大学大学院 工学研究科 電子工学/コンピュータ-サイエンス4, 大阪大学大学院 生命機能研究科 視覚神経科学5
Dept Social and Environmental Medicine, Grad Sch Medicine, Osaka Univ, Osaka1, Dept Biomedical and Molecular Sciences, Queens Univ, Ontario, Canada2, Moleculra Research Ceter for Children's Mental Development, Osaka Univ3, Grad Sch Engineering, Univ of Hyogo4, Visual Neuroscience Lab, Grad Sch Frontier Biosciences, Osaka Univ5

Attention-deficit/hyperactivity disorder (ADHD) has been considered to exert abnormal saccade, because fixation maintenance and saccade initiation are impaired (Munoz et al., 2003; McLoughlin et al., 2010). We measured a saccade behavior based on a psychophysical phenomenon, termed the gap effect, in which the transition from fixation to saccades is facilitated by the disappearance of a central visual stimulus, which allowed us to focus on saccade initiation, which might be more affected in ADHD. Seventy-seven patients (age, 7.5±2.5 yo) recruited at the Molecular Research Center for Children's Mental Development and 88 typically developing (TD) children (age, 7.8±1.9 yo) participated and instructed to fixate a central fixation point, then to make saccade to a peripheral target at either 16 degree of visual angle left or right from the center on a screen, and eye movements were recorded at 1 kHz using an infrared limbus tracking device. We used following two paradigmes, a saccade target appeared simultaneously as the fixation point disappeared (step condition), and a saccade target appeared 200 ms after the fixation point disappeared (gap condition), which reduced the saccade reaction times compared with the step condition. We analyzed using the following 2 methods: subtraction of average reaction times in gap and step conditions and a receiver operating characteristic (non-parametric) analysis. Consistent with previous studies, we found that the saccade reaction times were significantly longer in children with ADHD than in TD children, moreover the gap effect was attenuated to a greater extent in the ADHD group compared with the TD group. In a conceptual model of two distinct, reflexive and volitional, signals of fixation release mechanisms, our results suggested the volitional fixation signals were attenuated in ADHD children. Thus, the gap effect might be a potential biomarker to support diagnoses on ADHD children.
O1-8-1-2
ヒトマイクロサッケードは随意サッケード準備状態によって変化する
Modulation of microsaccades by volitional saccade preparations in humans

○小林康1,2,3,4, 松尾有華5, 査凌5, 渡辺雅之6,7
○Yasushi Kobayashi1,2,3,4, Yuka Matsuo5, Ling Zha5, Masayuki Watanabe6,7
大阪大学大学院 生命機能研究科 脳神経工学講座1, JSTさきがけ2, 脳情報通信融合研究センター3, 大阪大学社会経済研究所 行動経済学研究センター4, 大阪大学大学院 医学系研究科5, 関西医科大学 生理学第二6, カナダクイーンズ大学 神経科学研究センター7
Graduate School of Frontier Biosciences, Osaka University, Osaka1, PRESTO, The Japan Science and Technology Agency, Saitama2, Center for Information and Neural Network, Osaka3, Research Center for Behav. Economics, Osaka Univ., Osaka4, Dept. of Social and Environmental Medicine, Graduate School of Medicine, Osaka Univ., Osaka5, Dept. of Physiol., Kansai Medical University, Moriguchi, Osaka6, Centre for Neuroscience Studies, Queens University, Kingston, Ontario, Canada7

To examine preparatory and anticipatory state of action in humans, we measured miniature eye movements during fixation. We analysed microsaccades while adult humans maintained fixation on a central visual stimulus while they prepared to generate volitional saccades in response to peripheral stimulus appearance.We used the following two paradigms of saccades, the pro-saccade paradigm, in which subjects generate a saccade toward a peripheral stimulus and the anti-saccade paradigm, in which subjects generate a saccade toward the opposite direction of a peripheral stimulus. Here, appropriate anti-saccade performance requires the following two aspects of volitional control: 1) facilitation of saccade executions away from the stimulus; and 2) suppression of inappropriate pro-saccades toward the stimulus.Our findings are summarized in the following two points. First, pro- and anti-saccade initiation was facilitated with elapsed time from fixation initiation and temporal expectation of stimulus appearance. Such saccade facilitation is also reflected in reduction of microsaccade occurrence before appearance of peripheral stimulus. Second, microsaccades were suppressed by an anti-saccade instruction. Such suppression was diminished when subjects failed to cancel direction errors. This finding is supported further by the fact that subjects with higher microsaccade probabilities had poorer anti-saccade performance.These results suggest that dual preparatory signals for appropriate anti-saccade behavior can be read out by microsaccades. Thus, microsaccades can predict the outcome of future volitional actions, and may be used as a potential biomarker to detect people with difficulties in volitional action preparation.
O1-8-1-3
運動準備期間中のMEG脳活動を用いた反応時間の予測
Prediction of reaction time from MEG brain activity during motor preparation

○大畑龍1,2, 小川健二1,3, 今水寛1,4
○Ryu Ohata1,2, Kenji Ogawa1,3, Hiroshi Imamizu1,4
ATR認知機構研究所1, 大阪大学大学院生命機能研究科2, 日本学術振興会3, 情報通信研究機構・脳情報通信融合研究センター4
ATR Cognitive Mechanisms Labs., Kyoto, Japan1, Grad. Sch. of Frontier Biosciences, Osaka Univ., Osaka2, Japan Society for the Promotion of Science, Tokyo, Japan3, NICT Center for information & Neural Networks, Osaka, Japan4

Extracting the appropriate brain information before movement is one of the most important technologies for brain-machine interface. Recent studies showed that speed or reaction time during a reaching task can be predicted from brain activity during movement preparation measured with invasive neural recoding. However, prediction of movement parameters using non-invasive techniques remains to be developed. Given this situation, we examined whether it is possible to predict reaction time from brain activity during motor preparation measured with magnetoencephalography (MEG). In each trial, a high- or low-tone sound instructed subjects to move their fingertips with high or low peak velocities, respectively, within a range in which subjects were trained before MEG experiments. A target appeared over the central position 1300 ms after the sound. Subjects moved their right index finger to the target after the appearance of the target, adjusting the peak velocity according to the instruction sound. Based on the reaction time, individual trials were classified into long (top 30%) or short (bottom 30%) groups. We trained a classifier (sparse logistic regression: SLR) using the MEG sensor signals averaged within a moving time window of 100 ms before the target or movement onset, and predicted if subjects moved with long or short reaction time. The prediction accuracy was significantly above chance level (p<0.05) even when 400 ms before the target onset, as well as 700 ms before the movement onset. SLR frequently selected the central part of MEG channels near the supplementary motor area before the target onset, and the left posterior part of channels near the primary sensorimotor and parietal regions before the movement onset. Our results suggest that relatively long or short reaction time can be predicted from the activity before movement onsets, and that brain regions determining reaction time of the subsequent movements change according to the preparation stages.
O1-8-1-4
麻痺患者におけるPhase-amplitude couplingの検討
Deteriorated phase-amplitude coupling on sensorimotor cortices of paralyzed patients

○柳澤琢史1,2,3, 平田雅之1,2, 山下宙人3, 貴島晴彦1, 齋藤洋一1,5, 神谷之康3,4, 吉峰俊樹1
○Takufumi Yanagisawa1,2,3, Masayuki Hirata1,2, Okito Yamashita3, Haruhiko Kishima1, Youichi Saitoh1,5, Yukiyasu Kamitani3,4, Toshiki Yoshimine1
大阪大学大学院 医学系研究科 脳神経外科1, 大阪大学大学院 医学系研究科 保健学科 機能診断学2, 国際電気通信基礎技術研究所 脳情報研究所3, 奈良先端科学技術大学院大学4, 脳神経制御外科学5
Dept Neurosurgery, Osaka University Medical School, Osaka1, Division of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Osaka2, ATR Computational Neuroscience Laboratories, Kyoto3, Nara Institute of Science and Technology, Nara4, Dept Neuromodulation and neurosurgery, Osaka Univ, Osaka5

Neuronal oscillations in the sensorimotor cortex are characteristically modulated during preparation and execution of movements. We have shown that high-gamma amplitudes were coupled with alpha phases in the sensorimotor cortex of epilepsy patients. Moreover, the coupling was suggested to regulate the motor information represented by the high-gamma oscillations. On the other hand, we have demonstrated that the motor representation by the high-gamma amplitude was deteriorated among paralyzed patients due to stroke or trauma. Here, we have evaluated the phase-amplitude coupling on the sensorimotor cortices of the paralyzed patients to clarify the effect of the paresis on the coupling. ECoG signals were recorded from the sensorimotor cortices of 7 patients with paresis while three types of hand movements were performed or attempted. We found that the high-gamma amplitudes were coupled with the beta phase while patients were waiting for movement tasks. Coupling decreased toward the timing of motor execution or even attempt of movements, in parallel with the decrease in the beta amplitude. The strength of the coupling was deteriorated in the paralyzed patients compared to the patients without paresis. Our results demonstrated that phase-amplitude coupling exist even in the paralyzed patients with altered frequency properties and deteriorated strength. Coupling may relate to the pathological states of the sensorimotor cortices in the paralyzed patients.
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