感覚と運動は切り離せない―局所回路からBMIまで Fill missing links between sensory and motor processing -Viewpoints from microcircuit to BMI
S2-5-1-1 随意運動の制御における体性感覚入力の役割 Neural mechanisms underlying sensory gating during volitional hand movement ○関和彦1 ○Kazuhiko Seki1 国立精神・神経医療研究センター1 National Center of Neurology and Psychiatry1 "Every body movement stimulates peripheral sensory organs that activate neurons in the brain and spinal cord through a number of feedback pathways. How these feedback signals are processed within the central nervous system (CNS) in a manner relevant for the regulation of ongoing movement is an important question for the neural control of movement. In this talk, I would like to introduce our various approaches to address this issue. First, cutaneous sensory-evoked potentials (EPs) were recorded in the spinal cord, primary somatosensory and motor cortex, and premotor cortex in monkeys performing an instructed delay task. We found the size of EPs in all recorded area were suppressed in a task-dependent manner and this suppression seemed to be generated by both bottom-up and top-down mechanism. Synaptic mechanism that could induce this suppression was then investigated by means of “excitability testing”, a method to evaluate presynaptic inhibition on the peripheral afferent input to the spinal cord in awake, behaving monkeys. We found that somatosensory feedback from forearm afferent was suppressed presynaptically at the level of spinal cord during active torque generation. Preliminary evidence suggested that the modulation of the size of presynaptic inhibition were different between the terminal of muscle- and cutaneous afferent. Finally, presynaptic modulation of afferent input was also examined in human subject. Modulation of monosynaptic reflex in finger muscle via Ia afferent was examined in subjects performing different manipulation task by hand. We found that the size of monosynaptic responses were different in the different type of manipulation. These results suggest that presynaptic inhibitory mechanism regulates self-induced reafference from proprioceptor to motoneurone during hand manipulation, possibly depends on the level of dexterousness or difficulty required for each hand manipulation. Supports; JST-PREST, MEXT/JSPS Kakenhi 23135533, 23300143"	S2-5-1-2 外界との動的インタラクションのためのタスク指向的感覚調節 Task oriented sensory regulation for dynamic interaction with environments ○五味裕章1 ○Hiroaki Gomi1 NTTコミュニケーション科学基礎研究所1 NTT Comunication Science Laboratories1 Human arm has various dynamic interactions with environments for achieving numerous kinds of tasks. Previous studies revealed sophisticated arm-control mechanisms, such as a predictive internal model control and optimal feedback control, but mainly focus on the motor command programming. From the viewpoint of sensorimotor control, not only motor side but also sensory side could be modified and optimized according to the required tasks. In this talk, I will introduce two kinds of experimental observations which suggest sophisticated sensory regulation/tuning. The first one is a predictive somatosensory regulation during manual-hitting a virtual pack. In catch (fake-pack) trials in which impact force was not supplied, antagonist muscle exhibited a sharp EMG response just after the impact with the fake-pack. Such response was not observed when impact force was not supplied frequently. Given several control experiments, the results suggest a predictive and time-precise sensitivity regulation of sensory system associated with the antagonist-muscle shortening occurred by the pack collision. In the second example, I will introduce that visual-motion processing for hand control is largely distinct from that for eye control. According to the classical functional segregation theory in the brain processing, it has been generally believed that visual motion processing is unified for multiple brain functions. We found however that the quick hand and eye responses induced by visual motion differently varied with stimulus size/location and pattern smoothness (e.g., spatial frequency), suggesting that multiple visual motion processing streams for individual motor modalities that have different dynamic interaction with environments. Task oriented sensory regulation would be one of key mechanisms in the sensorimotor processing in the brain.
S2-5-1-3 The vibrissal system: open issues and perspective ○Martin Deschenes1 Université Laval, Québec, Canada1 "The vibrissal system of rodents mediates exploration, object localization and recognition, discrimination behavior, and spatial mapping of the environment. Whisker movements scan the environment, transforming the spatial properties of objects into spatio-temporal patterns of neural activity. Although signals arising from whisker contact are widely studied as a model of mammalian sensory processing, the correct interpretation of contact-induced activity in neural pathways depends on understanding how whisker movements are regulated; both because evoked activity in the somatosensory system differs according to whether a whisker is actively moved against an object or passively deflected, and because active control strategies constrain the types of sensory messages processed in downstream stations. Here I will present a short overview of the whisker system, and point out at important unresolved issues : (1) the role of the lemniscal and paralemniscal pathways, (2) the gating of sensory inputs during whisking, (3) the pathways that convey proprioceptive and tactile inputs, (4) and the central pattern generator for whisking. Through discussion of these topics, I will emphasize the necessity to consider the circuitry of the vibrissa system in light of the behavioral strategies of rodents, and that computations in the vibrissa system start and end at the brainstem."	S2-5-1-4 げっ歯類ヒゲシステムの紹介：運動と感覚の統合を研究する題材として Introduction of the rodent whisker system: as a good model for the study of motor-sensory integration ○古田貴寛1 ○Takahiro Furuta1 京都大学大学院　医学研究科　高次脳形態学教室1 Dept Morphological Brain Science, Graduate School of Medicine, Kyoto Univ, Kyoto1 Rodents possess long facial whiskers which are excellent tactile apparatuses and repeatedly sweep the whiskers back and forward to acquire rich sensory informations when they tactually locate and palpate objects. Although whisker movements are synchronous and periodic in the absence of whisker contact, contact with a object often induces asymmetries, asynchronies and changes in whisk amplitude and timing. These phenomena suggest that motor control and sensory processing are closely related to each other in the whisker system. Hear Dr Deschenes and I would introduce the whisker system as a good neurobehabioral model for the study of "motor-sensory integration": how the brain controls movements to process sensory input. Rodent whisker system further possess advantages that the whisker movement is relatively simple and thus easy to analyze and that we can directly investigate the structure of neural circuits by anatomical approaches. I will explain analogies and relationships between observations in studies of the whisker system and the topics of the latter speakers, Dr Gomi, Dr Seki and Dr Suminski. My talk will be presented in Japanese.
S2-5-1-5 Sensory-like responses in primary motor cortex enhance the performance of a brain-machine interface ○Aaron Suminski1, Dennis Tkach1, Andrew Fagg2, Nicholas Hatsopoulos1 Dept of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, USA1, School of Computer Science, University of Oklahoma, USA2 The ability to utilize information from both vision and proprioception is necessary for well-controlled, efficient motor behavior. Current brain-machine interfaces (BMI), however, largely rely on visual feedback to guide cursor or robot movements. We designed an experiment to test whether the addition of naturalistic proprioceptive feedback would improve the movement of a cortically-driven cursor. Two rhesus monkeys used a BMI to move a visual cursor and hit a sequence of randomly placed targets while resting their arm in a two-link robotic exoskeleton. A micro-electrode array composed of 100 electrodes was used to record the spiking activity of an ensemble of neurons in primary motor cortex (MI) under two conditions. In the first, Visual Feedback Decoding, the monkeys moved the cursor via the BMI and voluntarily maintained a static arm posture in the robotic exoskeleton. In the Visual and Proprioceptive Feedback Decoding condition, the monkeys controlled the cursor via the BMI while their arm was driven by the exoskeleton through the visual cursor trajectories. The data demonstrate that when the visual and proprioceptive feedback were congruent the time to successfully complete the task decreased, and the cursor paths became straighter as compared with the incongruent feedback condition. Examination of the neural discharge during the congruent feedback condition revealed two distinct populations of neurons in MI. The first population exhibited sensory-like responses with neurons discharging 60ms following movement of the BMI cursor. This response was not unique to the BMI task as these neurons discharged similarly when the monkeys moved their own limb. The behavior of the second population was consistent with the typical driving activity seen in MI (i.e. spiking that precedes movement by approximately 100ms). These findings provide the groundwork for augmenting cortically-controlled BMIs with multiple forms of natural or surrogate sensory feedback.

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