Sensory contributions to human movement and balance

人类保持直立姿势的任务涉及一个复杂的运动控制系统，它必须使用和整合主要来自三个感官来源的感觉信息：前庭系统、体感系统和视觉系统。我的基础研究计划的长期目标是更好地了解这些感官输入在控制人类站立平衡、运动和运动中所起的基础性作用。为了继续这一工作方向，将在未来5年内开展两个主要集中领域或主要研究方向。第一个主要集中区的短期目标将集中在两条下行运动通路对站立人体姿势肌单个运动神经元调节的影响，这两条下行运动通路直接受到这些感觉系统的影响。为了观察单个运动神经元的行为，我们开发了单个运动神经元的长期记录，使用定制的和非常稳定的留置导线记录电极。前庭脊髓和网状脊髓输入对安静站立时记录的单个运动单位的影响将被调查。前庭输入将通过电流前庭刺激(GVS)进行调制，而网状脊髓输入将使用响亮的声刺激来激活音频脊髓反射(ASR)。第二个主要集中区的短期目标将利用一种名为显微神经学的研究技术来研究人类肌梭(肌肉拉伸受体)的调节。我们计划研究在现实的生理主动和被动肌肉延长和缩短过程中，肢体肌梭的反应曲线。这些记录将首先在坐着的受试者中记录，试点实验已经证明，尽管非常困难，但从安静站立的受试者脚踝背屈肌轴的单个轴突记录是可能的，即使在站立扰动(脚踝足底/背屈)期间也是如此。这项拨款提案中的实验将为我们提供有价值的新见解，了解某些下行输入如何在正常站立时调节肌梭和运动单位的行为。

The task of maintaining upright stance in the human involves a complex motor control system that has to use and integrate sensory information from primarily three sensory sources: the vestibular system, the somatosensory system, and the visual system. The LONG TERM GOAL of my basic research program is to better understand the fundamental role played by these sensory inputs in the control of standing balance, locomotion and movement in humans. To continue with this direction of work, two main concentration areas or lines of research will be carried out over the next 5 years. The SHORT TERM goal of the first main concentration area of research will focus on the influence of two descending motor pathways that are directly influenced by these sensory systems, on the regulation of single motorneurons of postural muscles in standing human subjects. To look at single motorneuron behaviour, we have developed long term recordings of single motor units, using custom built and extremely stable indwelling wire recording electrodes. The influence of vestibulospinal and reticulospinal inputs onto single motor units recorded during quiet stance will be investigated. Vestibular inputs will be modulated using Galvanic Vestibular Stimulation (GVS), while reticulospinal inputs will be modulated using loud acoustic stimuli to activate the Audiospinal Reflex (ASR). The SHORT TERM goal of the second main concentration area will investigate the regulation of the human muscle spindles (muscle stretch receptors) utilizing a research technique termed microneurography. We plan to investigate the response profile of muscle spindles of the lower limb during realistic physiological active and passive muscle lengthening and shortening. These recordings will be first recorded in sitting subjects, and pilot experiments have demonstrated that, although very difficult, it is possible to record from the single axons from muscle spindles in ankle dorsiflexors in quietly standing human subjects, even during standing perturbations (ankle plantar/dorsiflexion). The experiments in this grant proposal will provide us with valuable new insight into how certain descending inputs regulate muscle spindle and motor unit behaviour during normal stance.