Mechanisms of Sensorimotor Integration

人的站姿本来就是不稳定的，即使是安静地站立，也会不断地出现微小的干扰和姿势的修正。控制人类的直立姿势需要感官输入来感知自己身体的运动和环境的运动之间的区别。这些输入包括(1)来自眼睛的视觉信息；(2)关于头部方向的前庭(内耳)信息；以及(3)来自肌肉和皮肤感受器的关于身体部分和外表面位置的体感(触摸)信息。大多数姿势控制研究都集中在通过实验操作或病理学来分离特定的感觉输入(例如，内耳不起作用的患者)，以确定单个感觉输入如何影响姿势控制。然而，单个输入很少孤立地工作，因此需要了解多个输入是如何交互的。这项研究分析了人类在同时操纵视觉和触觉两种感觉输入时的姿势控制。以前的研究表明，视觉可以影响姿势摆动：一个人静静地站在移动的视觉图案前，以视觉显示的频率摇摆。最近，我们实验室的实验表明，触觉同样可以影响摇摆。当人们用一根指尖轻轻触摸刚性表面时，姿势稳定性增强；如果被触摸的表面是移动的，则姿势摆动采用移动表面的频率。本研究的目的是同时提供视觉和触觉信息，以确定这两种感觉输入如何在控制姿势摆动中相互作用。个人将站在由随机点图案组成的可视显示器前。同时，他们会接触到一块坚硬的金属板。这些实验将探索当1)视觉线索是移动的而触摸线索是静态的，反之亦然时，姿势摆动是如何受到影响的；以及2)视觉和触摸线索都是移动的。问题是，姿势反应是由视觉或触觉主导的，还是获得了更复杂的关系。这些研究应该有助于从理论上更好地理解中枢神经系统如何处理复杂的感觉信息，并最终为因神经损伤(如中风)而丧失感觉功能的患者提供更好的康复技术。

Human standing posture is inherently unstable; even when one is standing quietly, small disturbances and corrections of posture occur continually. Control of human upright stance requires sensory input to perceive the distinction between movements of one's own body and movement of the environment. These inputs include (1) visual information from the eyes; (2) vestibular (inner ear) information about head orientation; and (3) somatosensory (touch) information about position of body segments and external surfaces, from receptors in the muscles and skin. Most postural control studies have focused on isolating a particular sensory input through experimental manipulation or pathology (e.g., patients without a functioning inner ear), to determine how an individual sensory input influences postural control. However, a single input rarely works in isolation and there is a need to understand how multiple inputs interact. The present study analyzes human postural control while simultaneously manipulating two sensory inputs, vision and touch. Previous studies have shown that vision can influence postural sway: A person standing quietly in front of a moving visual pattern sways at the frequency of the visual display. More recently, experiments in our lab have shown that the sense of touch can similarly influence sway. Postural stability was enhanced when people lightly touched a rigid surface with a single fingertip; and, if the touched surface was moving, postural sway assumed the frequency of the moving surface. The intent of the present study is to provide visual and touch information simultaneously, to determine how these two sensory inputs interact in the control of postural sway. Individuals will stand in front of a visual display consisting of a random dot pattern. At the same time they will touch a rigid metal plate. The experiments will explore how postural sway is influenced when 1) visual cues are moving and touch cues are static, and vice versa; and 2) visual and touch cues are both moving. The question is whether postural responses are dominated by vision or touch, or whether instead a more complex relationship obtains. These studies should lead to a better theoretical understanding of how the central nervous system processes complex sensory information, and eventually to better rehabilitative techniques for patients who have lost sensory function due to neurological injury (e.g., stroke).