Multi-level Dynamics of Action-Perception Patterns During Quiet Standing and Locomotion

人体姿势控制系统有两个主要功能：保持稳定的直立姿势，以及确定身体各部分的方向和位置，作为感知和行动的参照系。这项研究解决的问题是，如何整合各种信息来源以形成姿势目标，这些目标如何在干扰下稳定下来，以及当信息或任务发生变化时，这些目标如何灵活地重组。特别是，拟议的研究侧重于视觉对站立和移动时姿势稳定性的贡献。在实验研究中，人类参与者将观看计算机生成的视觉显示，同时监控他们的姿势反应。显示器模拟简单的场景，如隧道或走廊。这些场景通过头盔显示器显示，并使用检测参与者身体部位上红外线标记位置的系统来测量姿势反应。这项研究的动机是将姿态控制系统概念化为两级动力学系统。低级动力学实现了姿态的稳定和运动的恒速。高级动态通过将低级动态的参数调整到环境约束来实现灵活性。这种级别之间的划分通过将简单的控制策略组合在一起来实现灵活性。本研究的一个新贡献是对高层控制器如何影响低级控制器提出了具体建议。这些研究的结果将增加我们对人类姿势控制的理解，并可能为姿势控制障碍(例如，跌倒在老年人中)的补救措施指明方向。

The human postural control system serves two main functions: to maintain a stable upright posture, and to fix the orientation and position of the body segments that serve as a reference frame for perception and action. The question this research addresses is how various sources of information are integrated to form postural goals, how these goals are stabilized against perturbations, and how the goals are flexibly reorganized when the information or tasks change. In particular, the proposed research focuses on the contribution of vision to postural stability during standing and locomotion. In the experimental studies human participants will view computer-generated visual displays while their postural responses are monitored. The displays simulate simple scenes, such as a tunnel or hallway. The scenes are shown through a head-mounted display and postural responses are measured with a system that detects the position of infra-red markers on body segments of the participant. The research is motivated by a conceptualization of the postural control system as a two-level dynamical system. The low-level dynamics achieves postural stability and constant velocity of locomotion. The high-level dynamics achieves flexibility by tuning the parameters of the low-level dynamics to environmental constraints. This division between levels achieves flexibility by piecing together simple control strategies. A new contribution of this research is a concrete proposal as to how the high-level controller influences the low-level controller. The results of the studies will add to our understanding of human postural control, and may also point the way toward remedies for impairments of postural control (e.g., falling in the elderly).