EXTREME VESTIBULO-OCULAR ADAPTATION INDUCED BY PROLONGED OPTICAL REVERSAL OF VISION
EXTREME VESTIBULO-OCULAR ADAPTATION INDUCED BY PROLONGED OPTICAL REVERSAL OF VISION
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DOI：
10.1113/jphysiol.1976.sp011330
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发表时间：
1976-01-01
影响因子：
5.5
通讯作者：
MELVILLJONES, G
中科院分区：
文献类型：
--
作者：
GONSHOR, A;MELVILLJONES, G
研究了人类受试者在自由头部运动期间由于视觉长期光学逆转而导致的前庭眼反射（VOR）的塑性变化。水平视力翻转是由头戴式道威棱镜产生的。四名正常成年人分别连续暴露在这些条件下 2、6、7 和 27 天。先前显示为非习惯性的正弦旋转刺激（1/6 Hz；60°/s 幅度），用于在视力反转期间和恢复正常视力后的相同时期内以频繁的间隔在黑暗中测试 VOR。使用直流眼电图（EOG）记录眼球运动，注意避免由于视网膜的明/暗适应而导致EOG增益的变化。所有受试者在视力逆转的前两天均表现出 VOR 增益（眼速/头速）的大幅降低。 6、7 和 27 天的受试者表现出增重进一步减少，并在 1 周结束时达到正常值约 25% 的低平台。此时，一些 EOG 记录的衰减非常明显，以至于无法提取有意义的正弦信号。去除棱镜后，VOR 增益沿着接近原始自适应衰减的时间过程恢复。在为期 27 天的实验中，在视力反转的第 2 周期间，VOR 中出现了较大的相位变化。这些变化通常以滞后的方式进展，达到 130 度。到第 3 周开始时，相位相对于正常滞后。随之而来的是增益大幅恢复，从正常值的 25% 恢复到 50%。这些适应条件近似于反射的功能逆转，然后保持稳定，甚至过夜，直到第 28 天恢复正常视力。尽管 VOR 相位在 2 小时内恢复到接近正常，但增益的恢复还需要 2-3 周的时间。即使在与从一种稳态过渡到另一种稳态相关的大幅波动变化期间，瞬时增益和相位之间也存在高度系统化的关系。在这种转变过程中，VOR 有出现方向优势的趋势。所有观察到的变化都高度特定于视力反转平面，在矢状平面中没有观察到 VOR 变化。 VOR 变化是自适应的，因为它们始终以头部运动期间视网膜图像稳定的要求为目标。它们是可塑的，以至于对实现这一目标的反射进行了广泛且保留的重塑。所有观察到的增益和相位变化都与使用已知的前庭眼投影通过脑干和小脑通路的简单神经网络兼容，前提是反向视觉跟踪任务可以在小脑通路中产生功效的塑性调制，并且该通路表现出动态特性，在 1/6 Hz 的正弦信号中产生中等相位超前。
Plastic changes in the vestibulo-ocular reflex (VOR) of human subjects consequent to long-term optical reversal of vision during free head movement were investigated. Horizontal vision-reversal was produced by head-mounted dove prisms. Four normal adults were continuously exposed to these conditions during 2, 6, 7 and 27 days, respectively. A sinusoidal rotational stimulus, previously shown to be non-habituating (1/6 Hz; 60.degree./s amplitude), was used to test the VOR in the dark at frequent intervals both during the peroid of vision-reversal and an equal period after return to normal vision. DC electro-oculography (EOG) was used to record eye movement, taking care to avoid changes of EOG gain due to light/dark adaptation of the retina. All subjects showed substantial reduction of VOR gain (eye velocity/head velocity) during the 1st 2 days of vision-reversal. The 6-, 7- and 27-day subjects showed further reduction of gain which reached a low plateau at about 25% the normal value by the end of 1 wk. At this time the attenuation of some EOG records was so marked as to defy extraction of a meaningful sinusoidal signal. After removal of the prisms VOR gain recovered along a time course which approximated that of the original adaptive attenuation. In the 27-day experiment large changes of phase developed in the VOR during the 2nd wk of vision-reversal. These changes generally progressed in a lagging sense, to reach 130.degree. phase lag relative to normal by the beginning of the 3rd wk. Accompanying this was a considerable restoration of gain from 25 to 50% the normal value. These adapted conditions, which approximate functional reversal of the reflex, were then maintained steady, even overnight, until return to normal vision on the 28th day. Whereas VOR phase returned to near-normal in 2 h, restoration of gain occupied a further 2-3 wk. There was a highly systematic relation between instantaneous gain and phase, even during periods of widely fluctuating change associated with transition from 1 steady state to another. During such transition there was a tendency for directional preponderance to occur in the VOR. All the observed changes were highly specific to the plane of vision-reversal, no VOR changes being observed in the sagittal plane. VOR changes were adaptive, in the sense that they were always goal-directed towards the requirements of retinal image stabilization during head movement. They were plastic to the extent that there was extensive and retained remodeling of the reflex towards this goal. All the observed changes in gain and phase are compatible with a simple neural network employing known vestibulo-ocular projections via brainstem and cerebellar pathways, providing that the reversed visual tracking task can produce plastic modulation of efficacy in the cerebellar pathway and that this pathway exhibits a dynamic characteristic producing moderate phase lead in a sinusoidal signal at 1/6 Hz.