In normal humans, tapping the forehead produces a neck muscle reflex that is used clinically to test vestibular function, the cervical vestibular evoked myogenic potential (cVEMP). As stretch receptors can also be activated by skull taps, we investigated the origin of the early and late peaks of the bone-conducted cVEMP. In twelve normal participants, we differentially stimulated the vestibular and neck stretch receptors by applying vibration to the forehead (activating both vestibular and stretch receptors) and to the sternum (activating mainly stretch receptors). Patients with bilateral vestibulopathy (BVP; n = 26) and unilateral vestibular loss (uVL; n = 17) were also investigated for comparison. Comparison of peaks in normal subjects suggested that the early peaks were vestibular-dependent, while the later peaks had mixed vestibular and stretch input. The late peaks were present but small (1.1 amplitude ratio) in patients with BVP and absent VEMPs, confirming that they do not strictly depend on vestibular function, and largest in age-matched controls (1.5 amplitude ratio, p = 0.049), suggesting that there is an additional vestibular reflex at this latency (approx. 30 ms). Patients with uVL had larger late peaks on the affected than the normal side (1.4 vs 1.0 amplitude ratio, p = 0.034). The results suggest that the early responses in SCM to skull vibration in humans are vestibular-dependent, while there is a late stretch reflex bilaterally and a late vestibular reflex in the contralateral muscle.

中文翻译：

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人颈部肌肉中的骨传导前庭反射和拉伸反射。

在正常人中，轻拍额头会产生颈部肌肉反射，该反射可在临床上用于测试前庭功能，即颈前庭诱发的肌源性电位（cVEMP）。由于颅骨水龙头也可以激活拉伸受体，因此我们研究了骨传导cVEMP早期和晚期峰的起源。在十二名正常参与者中，我们通过对额头（激活前庭和拉伸受体）和胸骨（激活主要是拉伸受体）施加振动，从而差异地刺激前庭和颈部拉伸受体。还对患有双侧前庭病变（BVP； n = 26）和单侧前庭缺失（uVL； n = 17）的患者进行了比较。正常受试者峰的比较表明，早期峰是前庭依赖性的，而后来的山峰混合了前庭和伸展的输入。BVP和VEMP缺失的患者存在较晚的峰值，但较小（1.1振幅比），这表明它们并不严格依赖前庭功能，在年龄匹配的对照组中最大（1.5振幅比，p = 0.049），表明在此等待时间（约30毫秒）处会有一个额外的前庭反射。uVL患者的患病晚期峰比正常侧大（1.4 vs 1.0振幅比，p = 0.034）。结果表明，SCM对人类头骨振动的早期反应是前庭依赖性的，而双侧则有晚期拉伸反射，对侧肌肉中有晚期前庭反射。证实它们并不严格取决于前庭功能，并且在年龄匹配的对照中最大（1.5振幅比，p = 0.049），表明在此潜伏期（约30 ms）还有额外的前庭反射。uVL患者的患病晚期峰比正常侧大（1.4 vs 1.0振幅比，p = 0.034）。结果表明，SCM对人类头骨振动的早期反应是前庭依赖性的，而双侧则有晚期拉伸反射，对侧肌肉中有晚期前庭反射。证实它们并不严格取决于前庭功能，并且在年龄匹配的对照组中最大（1.5振幅比，p = 0.049），这表明在该潜伏期（约30 ms）还有额外的前庭反射。uVL患者的患病晚期峰较正常侧大（1.4 vs 1.0振幅比，p = 0.034）。结果表明，SCM对人类头骨振动的早期反应是前庭依赖性的，而双侧则有晚期拉伸反射，对侧肌肉中有晚期前庭反射。0振幅比，p = 0.034）。结果表明，SCM对人类头骨振动的早期反应是前庭依赖性的，而双侧则有晚期拉伸反射，对侧肌肉中有晚期前庭反射。0振幅比，p = 0.034）。结果表明，SCM对人类头骨振动的早期反应是前庭依赖性的，而双侧则有晚期拉伸反射，对侧肌肉中有晚期前庭反射。