Enhanced excitability of the human visual cortex induced by short-term light deprivation
Enhanced excitability of the human visual cortex induced by short-term light deprivation
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DOI：
10.1093/cercor/10.5.529
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发表时间：
2000-05-01
期刊：
影响因子：
3.7
通讯作者：
Cohen, LG
中科院分区：
文献类型：
--
作者：
Boroojerdi, B;Bushara, KO;Cohen, LG
长期剥夺视觉输入数天或数周会导致枕叶皮层的兴奋性和功能发生显著变化。人们对这些变化的时间进程知之甚少。在这项研究中，我们解决了一个问题，即短时间的光剥夺（几分钟到几个小时）是否会引起人类的这种变化。无创经颅磁刺激（TMS）人类枕叶皮层可以唤起闪光或光点（光幻视）的感知。为了评估光剥夺后视觉皮层兴奋性的变化，我们测量了引发光幻视所需的最低刺激强度（光幻视阈值）和不同TMS刺激强度引发的光幻视数量（刺激-反应曲线）。光剥夺开始45分钟后，光幻视阈值降低，并持续整个剥夺期（180分钟）。再次暴露于光后，光幻视阈值在120分钟内恢复到剥夺前的值。刺激-反应曲线在干预后显著增强。在第二个实验中，我们研究了光剥夺对光刺激引发的功能磁共振成像（fMRI）信号的影响。功能磁共振成像结果显示，60分钟的光剥夺后，视觉皮层的激活增加，这种情况在30分钟的光再次暴露后持续存在。我们的结果显示，视觉皮层的兴奋性显著增加。据报道，这些变化可能是人类和动物在被剥夺光线后行为改善的基础。
Long term deprivation of visual input for several days or weeks leads to marked changes in the excitability and function of the occipital cortex. The time course of these changes is poorly understood. In this study, we addressed the question whether a short period of light deprivation (minutes to a few hours) can elicit such changes in humans. Noninvasive transcranial magnetic stimulation (TMS) of the human occipital cortex can evoke the perception of flashes or spots of light (phosphenes). To assess changes in visual cortex excitability following light deprivation, we measured the minimum intensity of stimulation required to elicit phosphenes (phosphene threshold) and the number of phosphenes elicited by different TMS stimulus intensities (stimulus-response curves). A reduced phosphene threshold was detected 45 min after the onset of light deprivation and persisted for the entire deprivation period (180 min). Following re-exposure to light, phosphene thresholds returned to predeprivation values over 120 min. Stimulus-response curves were significantly enhanced in association with this intervention. In a second experiment, we studied the effects of light deprivation on functional magnetic resonance imaging (fMRI) signals elicited by photic stimulation. fMRI results showed increased visual cortex activation after 60 min of light deprivation that persisted following 30 min of re-exposure to light. Our results demonstrated a substantial increase in visual cortex excitability. These changes may underlie behavioral gains reported in humans and animals associated with light deprivation.