School of Human Kinetics, Osborne Centre Unit II, 6108 Thunderbird Boulevard, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.
Neuroscience. 2009 Dec 15;164(3):986-97. doi: 10.1016/j.neuroscience.2009.07.042. Epub 2009 Jul 25.
The purpose of the study was to determine whether the central nervous system (CNS) requires the sensory feedback generated by balance perturbations in order to trigger postural responses (PRs). In Experiment 1, twenty-one participants experienced toes-up support-surface tilts in two blocks. Control blocks involved unexpected balance perturbations whereas an auditory tone cued the onset of balance perturbations in Conditioning blocks. A single Cue-Only trial followed each block (Cue-Only(Control) and Cue-Only(Conditioning) trials) in the absence of balance perturbations. Cue-Only(Conditioning) trials were used to determine whether postural perturbations were required in order to trigger PRs. Counter-balancing the order of Control and Conditioning blocks allowed Cue-Only(Control) trials to examine both the audio-spinal/acoustic startle effects of the auditory cue and the carryover effects of the initial conditioning procedure. In Experiment 2, six participants first experienced five consecutive Tone-Only trials that were followed by twenty-five conditioning trials. After conditioning, five Tone-Only trials were again presented consecutively to first elicit and then extinguish the conditioned PRs. Surface electromyography (EMG) recorded muscle activity in soleus (SOL), tibialis anterior (TA) and rectus femoris (RF). EMG onset latencies and amplitudes were calculated together with the onset latency, peak and time-to-peak of shank angular accelerations. Results indicated that an auditory cue could be conditioned to initiate PRs in multiple muscles without balance-relevant sensory triggers generated by balance perturbations. Postural synergies involving excitation of TA and RF and inhibition of SOL were observed following the Cue-Only(Conditioning) trials that resulted in shank angular accelerations in the direction required to counter the expected toes-up tilt. Postural synergies were triggered in response to the auditory cue even 15 min post-conditioning. Furthermore, conditioned PRs were quickly extinguished as participants became unresponsive by the third trial in extinction. In conclusion, our results reveal that the CNS does not require sensory feedback from postural perturbations in order to trigger PRs.
本研究旨在确定中枢神经系统（CNS）是否需要平衡扰动产生的感觉反馈来触发姿势反应（PR）。在实验 1 中，21 名参与者在两个块中经历了脚趾向上的支撑面倾斜。对照块涉及意外的平衡扰动，而听觉提示则在条件化块中提示平衡扰动的开始。在没有平衡扰动的情况下，每个块之后都有一个单独的仅提示试验（仅提示（对照）和仅提示（条件化）试验）。仅提示（条件化）试验用于确定是否需要姿势扰动来触发 PR。对照块和条件化块的顺序平衡允许仅提示（对照）试验同时检查听觉提示的音频-脊髓/声学惊吓效应和初始条件化程序的延续效应。在实验 2 中，6 名参与者首先经历了五个连续的仅提示试验，然后是 25 个条件化试验。条件化后，再次连续呈现五个仅提示试验，首先引出并随后熄灭条件化的 PR。表面肌电图（EMG）记录了比目鱼肌（SOL）、胫骨前肌（TA）和股直肌（RF）的肌肉活动。计算了 EMG 起始潜伏期和幅度，以及小腿角度加速度的起始潜伏期、峰值和到达峰值时间。结果表明，听觉提示可以被条件化以在没有由平衡扰动产生的与平衡相关的感觉触发的情况下引发 PR。在导致小腿角度加速度的仅提示（条件化）试验后，观察到涉及 TA 和 RF 兴奋和 SOL 抑制的姿势协同作用，以抵消预期的脚趾向上倾斜。即使在条件化后 15 分钟，即使在听觉提示后，姿势协同作用也会被触发。此外，随着参与者在消退中的第三个试验变得无反应，条件化的 PR 迅速消退。总之，我们的结果表明，CNS 不需要来自姿势扰动的感觉反馈来触发 PR。
