Rapid and reversible recruitment of early visual cortex for touch.
Rapid and reversible recruitment of early visual cortex for touch.
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DOI：
10.1371/journal.pone.0003046
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发表时间：
2008-08-27
期刊：
影响因子：
3.7
通讯作者：
Pascual-Leone A
中科院分区：
文献类型：
--
作者：
Merabet LB;Hamilton R;Schlaug G;Swisher JD;Kiriakopoulos ET;Pitskel NB;Kauffman T;Pascual-Leone A
视力丧失与非视觉任务的表现增强有关，如触觉辨别和声音定位。目前的证据表明，这些功能的获得与枕叶视觉皮质的非视觉处理招募有关，但这些交叉模式变化背后的神经生理学机制仍然不确定。一种可能的解释是，视觉剥夺与非视觉输入进入视觉皮质的行为被揭开有关。我们研究了突然的、完全的和长时间的视觉剥夺(5天)对处于高强度触觉训练中的正常视力成年人的影响。在五天的时间里，被蒙住眼睛的受试者在盲文字符辨别任务中表现更好。在盲目组中，连续的fMRI扫描显示，在完全丧失视觉的五天后，枕叶皮质对触觉刺激的反应增加了BOLD信号。摘除眼罩24小时后，这种信号的增加不再存在。最后，第5天枕叶皮质功能的可逆性破坏(通过重复的经颅磁刺激；rTMS)损害了盲目组的盲文字符识别能力，但在非蒙眼对照组中没有。一旦摘除眼罩24小时，这种破坏作用就不再明显。总体而言，我们的发现表明，对于正常视力的人来说，突然而完全的视觉剥夺可能会导致深刻的、但迅速可逆的神经可塑性变化，枕叶皮质通过这种变化参与非视觉信息的处理。观察到的变化的速度和动态性质表明，视力丧失揭示了视力正常被抑制或被掩盖的功能。先前存在的连接的揭开和连接的转变代表着快速的、早期的可塑性变化，如果持续和加强，这种变化可能会导致发展较慢、但更持久的结构性变化，例如在盲人中建立新的神经连接。
The loss of vision has been associated with enhanced performance in non-visual tasks such as tactile discrimination and sound localization. Current evidence suggests that these functional gains are linked to the recruitment of the occipital visual cortex for non-visual processing, but the neurophysiological mechanisms underlying these crossmodal changes remain uncertain. One possible explanation is that visual deprivation is associated with an unmasking of non-visual input into visual cortex. We investigated the effect of sudden, complete and prolonged visual deprivation (five days) in normally sighted adult individuals while they were immersed in an intensive tactile training program. Following the five-day period, blindfolded subjects performed better on a Braille character discrimination task. In the blindfold group, serial fMRI scans revealed an increase in BOLD signal within the occipital cortex in response to tactile stimulation after five days of complete visual deprivation. This increase in signal was no longer present 24 hours after blindfold removal. Finally, reversible disruption of occipital cortex function on the fifth day (by repetitive transcranial magnetic stimulation; rTMS) impaired Braille character recognition ability in the blindfold group but not in non-blindfolded controls. This disruptive effect was no longer evident once the blindfold had been removed for 24 hours. Overall, our findings suggest that sudden and complete visual deprivation in normally sighted individuals can lead to profound, but rapidly reversible, neuroplastic changes by which the occipital cortex becomes engaged in processing of non-visual information. The speed and dynamic nature of the observed changes suggests that normally inhibited or masked functions in the sighted are revealed by visual loss. The unmasking of pre-existing connections and shifts in connectivity represent rapid, early plastic changes, which presumably can lead, if sustained and reinforced, to slower developing, but more permanent structural changes, such as the establishment of new neural connections in the blind.
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