年龄相关的前庭眼反射增益下降与对电前庭刺激的摆动反应增加相关

文献信息

中文摘要

尽管随着年龄增长，外周前庭输入显著丧失，但功能变化相对较小。这引发了推测，即中枢神经增益的增加可减轻此类损失。在此，我们通过比较整个生命周期中前庭眼反射（VOR）的增益与对电前庭刺激（EVS）的反应来检验这一假设。VOR评估完整的前庭-运动通路，而EVS绕过外周前庭力学。因此，两者之间的任何分离可能揭示中枢与外周功能的差异。使用旋转椅评估了62名年龄20-87岁参与者的VOR增益。随后在同一天对相同参与者测试了EVS诱发的姿势摆动反应。我们发现VOR增益随年龄显著降低（r = -0.48，p < 0.001），EVS增益增加（r = 0.36，p = 0.004），且两者呈负相关（r = -0.35，p = 0.006）。EVS反应与中枢神经增益的增加一致。我们还观察到VOR相位超前随年龄增加。这可能损害VOR准确性，从而限制补偿的程度，解释了为何VOR增益随年龄下降。这些结果表明对年龄相关外周损失的部分神经补偿。然而，即使排除年龄因素，VOR与EVS增益之间的负相关仍然存在（r = -0.28，p = 0.031）。这表明中枢神经系统的一般特性，即神经增益被调整以匹配外周前庭输入的个体间差异。

英文摘要

Despite considerable loss of peripheral vestibular input with age, there is relatively little change in function. This has led to speculation that increasing central neural gain mitigates such losses. Here, we test this hypothesis by comparing the gain of the vestibulo-ocular reflex (VOR) with the response to electrical vestibular stimulation (EVS) across the lifespan. The VOR assesses the full vestibulo-motor pathway, whereas EVS bypasses the peripheral vestibular mechanics. Hence, any dissociation between the two may reveal a difference in central versus peripheral function. A rotating chair was used to assess VOR gain in 62 participants aged 20-87 yr. EVS-evoked postural sway responses were then tested in the same participants on the same day. We found a significant age-related reduction in VOR gain (r = -0.48, P < 0.001), an increase in EVS gain (r = 0.36, P = 0.004), and an inverse correlation between the two (r = -0.35, P = 0.006). The EVS response is consistent with an increase in central neural gain. We also observed an increase in VOR phase lead with age. This may impair VOR accuracy, thus imposing limits on the extent of compensation, explaining why VOR gain declined with age. These results demonstrate partial neural compensation for age-related peripheral loss. However, the inverse correlation between VOR and EVS gain persisted even when age was factored out (r = -0.28, P = 0.031). This suggests a general property of the central nervous system whereby neural gain is tuned to match interpersonal differences in peripheral vestibular input.NEW & NOTEWORTHY Up to 40% of vestibular hair cells are lost by age 70, but eye movements are only mildly affected, suggesting peripheral loss is mitigated by increasing neural gain. We investigated this hypothesis by applying electrical vestibular stimulation (EVS) to estimate central gain in volunteers aged 20-87 yr. EVS-evoked balance responses systematically increased with age, whereas vestibular-ocular reflex gain reduced. This is consistent with an increase in central neural gain to compensate for age-related peripheral loss.