Department of Public Health, Experimental and Forensic Medicine, University of Pavia Pavia, Italy.
Department of Public Health, Experimental and Forensic Medicine, University of Pavia Pavia, Italy ; Centro Studi Attività Motorie (CSAM), Fondazione Salvatore Maugeri (IRCSS), Scientific Institute of Pavia Pavia, Italy.
Front Syst Neurosci. 2014 Oct 6;8:190. doi: 10.3389/fnsys.2014.00190. eCollection 2014.
Maintaining equilibrium is basically a sensorimotor integration task. The central nervous system (CNS) continually and selectively weights and rapidly integrates sensory inputs from multiple sources, and coordinates multiple outputs. The weighting process is based on the availability and accuracy of afferent signals at a given instant, on the time-period required to process each input, and possibly on the plasticity of the relevant pathways. The likelihood that sensory inflow changes while balancing under static or dynamic conditions is high, because subjects can pass from a dark to a well-lit environment or from a tactile-guided stabilization to loss of haptic inflow. This review article presents recent data on the temporal events accompanying sensory transition, on which basic information is fragmentary. The processing time from sensory shift to reaching a new steady state includes the time to (a) subtract or integrate sensory inputs; (b) move from allocentric to egocentric reference or vice versa; and (c) adjust the calibration of motor activity in time and amplitude to the new sensory set. We present examples of processes of integration of posture-stabilizing information, and of the respective sensorimotor time-intervals while allowing or occluding vision or adding or subtracting tactile information. These intervals are short, in the order of 1-2 s for different postural conditions, modalities and deliberate or passive shift. They are just longer for haptic than visual shift, just shorter on withdrawal than on addition of stabilizing input, and on deliberate than unexpected mode. The delays are the shortest (for haptic shift) in blind subjects. Since automatic balance stabilization may be vulnerable to sensory-integration delays and to interference from concurrent cognitive tasks in patients with sensorimotor problems, insight into the processing time for balance control represents a critical step in the design of new balance- and locomotion training devices.
维持平衡基本上是一种感觉运动整合任务。中枢神经系统 (CNS) 不断地、有选择性地对来自多个来源的感觉输入进行加权和快速整合，并协调多个输出。加权过程基于在给定时刻传入信号的可用性和准确性、处理每个输入所需的时间以及相关通路的可塑性。在静态或动态条件下平衡时，感觉传入变化的可能性很高，因为受试者可以从黑暗环境进入明亮环境，或者从触觉引导的稳定状态转变为触觉传入的丧失。这篇综述文章介绍了伴随感觉转换的最新时间事件数据，这些数据的基础信息是零散的。从感觉转变到达到新的稳定状态的处理时间包括以下三个部分：(a) 减去或整合感觉输入；(b) 从以物体为中心的参考系转换到以自我为中心的参考系，或者反之；(c) 及时调整运动活动的校准以适应新的感觉集。我们展示了姿势稳定信息整合的过程实例，以及在允许或遮挡视觉或添加或减去触觉信息时相应的感觉运动时间间隔。这些间隔很短，对于不同的姿势状态、模态以及有意或被动转换，时间间隔在 1-2 秒之间。与视觉转换相比，触觉转换的时间间隔稍长；与添加稳定输入相比，撤回稳定输入的时间间隔更短；与意外模式相比，有意模式的时间间隔更短。在盲人群体中，延迟时间最短（用于触觉转换）。由于自动平衡稳定可能容易受到感觉运动整合延迟和来自同时进行的认知任务的干扰，因此，深入了解平衡控制的处理时间是设计新的平衡和运动训练设备的关键步骤。
