Fitzpatrick Richard C, Watson Shaun R D
Neuroscience Research Australia and University of New South Wales, Sydney, Australia.
Institute of Neurological Sciences, Prince of Wales Hospital, Sydney, Australia.
J Physiol. 2015 May 15;593(10):2389-98. doi: 10.1113/JP270334.
With the hypothesis that vestibular sensitivity is regulated to deal with a range of environmental motion conditions, we explored the effects of passive whole-body motion on vestibular perceptual and balance responses. In 10 subjects, vestibular responses were measured before and after a period of imposed passive motion. Vestibulospinal balance reflexes during standing evoked by galvanic vestibular stimulation (GVS) were measured as shear reaction forces. Perceptual tests measured thresholds for detecting angular motion, perceptions of suprathreshold rotation and perceptions of GVS-evoked illusory rotation. The imposed conditioning motion was 10 min of stochastic yaw rotation (0.5-2.5 Hz ≤ 300 deg s(-2) ) with subjects seated. This conditioning markedly reduced reflexive and perceptual responses. The medium latency galvanic reflex (300-350 ms) was halved in amplitude (48%; P = 0.011) but the short latency response was unaffected. Thresholds for detecting imposed rotation more than doubled (248%; P < 0.001) and remained elevated after 30 min. Over-estimation of whole-body rotation (30-180 deg every 5 s) before conditioning was significantly reduced (41.1 to 21.5%; P = 0.033). Conditioning reduced illusory vestibular sensations of rotation evoked by GVS (mean 113 deg for 10 s at 1 mA) by 44% (P < 0.01) and the effect persisted for at least 1 h (24% reduction; P < 0.05). We conclude that a system of vestibular sensory autoregulation exists and that this probably involves central and peripheral mechanisms, possibly through vestibular efferent regulation. We propose that failure of these regulatory mechanisms at different levels could lead to disorders of movement perception and balance control during standing.
基于前庭敏感性受调节以应对一系列环境运动条件的假设，我们探究了被动全身运动对前庭感知和平衡反应的影响。在10名受试者中，在一段被动运动期前后测量前庭反应。通过电流前庭刺激（GVS）诱发的站立时前庭脊髓平衡反射作为剪切反作用力进行测量。感知测试测量了检测角运动的阈值、阈上旋转的感知以及GVS诱发的虚幻旋转的感知。施加的条件性运动是让受试者坐着进行10分钟的随机偏航旋转（0.5 - 2.5 Hz≤300度每秒(-2)）。这种条件作用显著降低了反射性和感知性反应。中等潜伏期的电流反射（300 - 350毫秒）幅度减半（48%；P = 0.011），但短潜伏期反应未受影响。检测施加旋转的阈值增加了一倍多（248%；P < 0.001），并且在30分钟后仍保持升高。条件作用前对全身旋转（每5秒30 - 180度）的高估显著降低（从41.1%降至21.5%；P = 0.033）。条件作用降低了GVS诱发的虚幻前庭旋转感觉（1毫安时10秒内平均113度）44%（P < 0.01），并且这种效果持续至少1小时（降低24%；P < 0.05）。我们得出结论，存在前庭感觉自动调节系统，这可能涉及中枢和外周机制，可能是通过前庭传出调节。我们提出，这些不同水平调节机制的失效可能导致站立时运动感知和平衡控制障碍。
