Sensorimotor processing and body motion perception

人类的直立平衡天生就不稳定。为了保持平衡，来自不同传感器的信息被结合在一起；每个感官线索都提供了关于身体摇摆的有价值的信息。虽然平衡控制可以通过单一的感觉线索来实现，但当所有的感觉线索都被处理好时，平衡控制才是最好的。为了评估每一种感觉线索的作用，通常通过实验来诱导感觉错觉。本研究计划的第一个目标是评估对前庭或视觉刺激的平衡控制阈值。为了实现这一目标，我们将改变前庭或视觉信息。在正常直立时，作用于头部的加速度是由前庭系统检测到的。前庭系统对平衡控制的贡献可以通过通过耳朵施加小电流来评估。因此，当参与者站着时，将会施加小电流。为了确定视觉刺激的平衡控制阈值，参与者将观看显示旋转圆点的大屏幕。平衡控制阈值将使用先进的信号处理技术来确定。视觉系统在帮助维持人体平衡方面发挥着重要作用，因为视觉线索提供了关于意外身体摆动的信息。在日常生活中，当一个人静止不动时，视觉环境的速度可能不代表他/她的身体运动。在这种情况下，大脑需要检测视觉信息是否与身体运动或环境有关。这项建议的第二个目标将是确定前庭暗示对视觉诱发姿势反应的贡献。为了做到这一点，我们将创造一种错觉，即身体移动得比它本身更快。创造感觉不匹配将使我们能够评估大脑如何利用感觉信息在视觉刺激过程中摆动身体。许多研究报告了感觉增强(SA)期间平衡控制的改善。SA是传递额外的感觉线索，例如通过触觉信息，传达关于身体摇摆的相关信息。然而，有限的研究调查了其有效性的潜在神经机制。为了解决文献中的这一差距，我们将通过脑电(EEG)记录大脑活动，同时参与者控制他们的平衡并接受SA。通过比较平衡控制中使用和不使用SA时的脑活动，我们将量化与SA相关的脑活动的变化。这将使我们能够确定SA对大脑活动和平衡控制改善的有效性。总体而言，这项研究计划将提供有关平衡控制和身体运动感知的潜在机制的重要基础知识。此外，这项工作可以促进假肢使用者感知界面的进步，开发导航设备或传感器来增强机器人的平衡控制。

Human upright balance is inherently unstable. To maintain balance, information from various sensors are combined; each sensory cue provides valuable information on body sway. Although balance control is possible with a single sensory cue, balance control is best when all sensory cues are processed. To assess the role of each sensory cue, it is common to experimentally induce sensory illusion. The first aim of this research program is to assess the balance control threshold to a vestibular or a visual stimulation. To pursuit this aim, we will alter vestibular or visual information. During normal upright standing, acceleration acting on the head are detected by the vestibular system. Contribution of the vestibular system to balance control can be evaluated by applying a small current through the ears. Thus, small current will be applied while participants will be standing. To determine the balance control threshold to a visual stimulation, participants will look at a large screen displaying rotating dots. Balance control threshold will be determined using advanced signal processing techniques. The visual system plays an important role in helping to maintain human balance as visual cues provide information about unintended body sway. In daily life, when one stands still, it is possible that the velocity of the visual surround does not represent his/her body motion. In such a situation, the brain needs to detect if visual information relates to body motion or to the environment. The second aim of this proposal will be to determine the contribution of vestibular cues to a visual evoked postural response. To do so, we will create the illusion that the body is moving faster than it is. Creating sensory mismatch will allow us to assess how the brain uses sensory information to body sway during visual stimulation. Many studies have reported improvement in balance control during sensory augmentation (SA). SA is the delivery of additional sensory cues, e.g. via tactile information, that convey pertinent information about body sways. Limited studies, however, have investigated the underlying neural mechanisms of its effectiveness. To address this gap in the literature, we will record brain activity through electroencephalography (EEG) while participants control their balance and receive SA. By comparing brain activity during balance control with and without SA, we will quantify the change in brain activity related to SA. This will allow us to determine the effectiveness of SA on brain activity and balance control improvement. Overall, this research program will provide important fundamental knowledge regarding the underlying mechanisms involved in balance control and body motion perception. Further, this work can contribute to the advancement of sensory interface for prosthesis users, the development of navigation devices or sensors to enhance robots balance control.