School of Medicine, Western Sydney University, Sydney, New South Wales, Australia.
School of Civil Engineering, University of Sydney, Sydney, New South Wales, Australia.
J Neurophysiol. 2020 Dec 1;124(6):1551-1559. doi: 10.1152/jn.00177.2020. Epub 2020 Sep 23.
Sopite syndrome, centered around the drowsiness, lethargy, and irritability associated with motion sickness, can be induced by exposure to low-frequency motion. It is known that the vestibular apparatus plays an important role in the pathogenesis of motion sickness, which features several autonomic responses, and we have previously documented increased vestibular modulation of skin sympathetic nerve activity (SSNA) and an increase in skin blood flow associated with nausea. Here, we assessed whether imperceptibly slow sinusoidal motion, sufficient to induce sopite syndrome but not nausea, also modulates SSNA and skin blood flow. Participants were seated upright and exposed to a randomized set of sinusoidal linear accelerations, ranging from 0.03 Hz at 0.5 mG to 0.2 Hz at 5 mG, via a motorized platform. At all frequencies vestibular modulation was greater than the cardiac modulation of SSNA, but cardiac modulation and skin blood flow were both significantly lower during the motion than at baseline. We conclude that sopite syndrome is associated with a marked modulation of sympathetic outflow to the skin and cutaneous vasoconstriction. Little is known about the autonomic consequences of sopite syndrome-the drowsiness that can be induced by low-amplitude cyclic motion. We recorded skin sympathetic nerve activity (SSNA) in seated participants exposed to slow sinusoidal linear acceleration (0.03-0.2 Hz), which preferentially activates hair cells in the utricular part of the otolithic organs, at amplitudes that generated no sensations of motion. At all frequencies, there was a clear vestibular modulation of SSNA and cutaneous vasoconstriction.
嗜睡症是以晕车相关的困倦、昏睡和易怒为中心的综合征，可能由低频运动引起。已知前庭器官在晕车的发病机制中起重要作用，其具有几种自主反应，我们之前记录到与恶心相关的皮肤交感神经活动（SSNA）和皮肤血流量增加与前庭调制增加有关。在这里，我们评估了足以引起嗜睡症但不会引起恶心的不可察觉的缓慢正弦运动是否也调节 SSNA 和皮肤血流量。参与者直立坐在机动平台上，接受一组随机的正弦线性加速度刺激，范围从 0.03 Hz 的 0.5 mG 到 0.2 Hz 的 5 mG。在所有频率下，前庭调制都大于 SSNA 的心脏调制，但在运动期间，心脏调制和皮肤血流量都明显低于基线。我们得出结论，嗜睡症与皮肤交感神经传出的明显调制和皮肤血管收缩有关。关于嗜睡症（可由低幅度循环运动引起的嗜睡）的自主后果知之甚少。我们记录了在坐姿参与者中暴露于缓慢正弦线性加速度（0.03-0.2 Hz）时的皮肤交感神经活动（SSNA），该运动优先激活耳石器官的耳石器部分中的毛细胞，其幅度不会产生运动感觉。在所有频率下，SSNA 和皮肤血管收缩均有明显的前庭调制。
