The vestibular system was activated by galvanic electrical stimulation in 19 normal subjects. With the head turned to one side so that the stimulating anode was on the posterior mastoid process, stimulation caused standing subjects to sway backwards in the sagittal plane. Electromyography showed bilateral activation of erector spinae, gluteus maximus, biceps femoris, soleus and intrinsic foot (toe flexor) muscles. When head direction or electrode polarity was reversed so that the anode was anterior, all those muscles became less active and the subjects swayed forwards. With the head facing forward, stimulation caused sideways sway in the coronal plane, towards the anode, with excitation of the erector spinae on the anode side and reduced activity on the cathode side. The limb muscles were activated on the side opposite the anode and showed complex responses on the anode side. Responses were detectable in the erectores spinae muscles in sitting subjects. No responses in limb muscles were detected in the sitting posture. Subject responses in erector spinae recorded at L3/L4 had latencies from 59 to 110 ms, using a 2 mA stimulus. Latencies in lower limb muscles were longer. The results suggest a role for the vestibular system and descending brain stem motor pathways to the erectores spinae muscles in the control of postural orientation of the back when sitting and standing. The conduction velocity in the motor pathway was estimated to be 13 ± 10 m s−1 (mean ± s.d., n = 12 subjects).
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机译：在19名正常受试者中，通过电流电刺激激活了前庭系统。头部转向一侧，使刺激阳极位于乳突后部，刺激使站立的受试者在矢状面内向后摆动。肌电图显示双侧激活竖脊肌，臀大肌，股二头肌，比目鱼肌和固有足（趾屈肌）肌肉。当头部方向或电极极性反转以使阳极在前时，所有这些肌肉的活动性降低，受试者向前摆动。头部朝前，刺激在冠状平面内向阳极侧向摇摆，在阳极侧激发竖脊肌并在阴极侧降低活性。肢体肌肉在与阳极相对的一侧被激活，并在阳极一侧显示出复杂的响应。在坐着的受试者的竖脊肌中可检测到反应。坐姿未检测到四肢肌肉反应。使用2 mA刺激，以L3 / L4记录的竖脊肌的受试者反应潜伏期为59到110 ms。下肢肌肉的潜伏期较长。结果表明，前庭和站立时，前庭系统和降落的脑干运动路径通往竖脊肌的作用在控制背部的姿势方向中起作用。运动路径中的传导速度估计为13±10 m s -1 （平均值±s.d.，n = 12位受试者）。
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