Temporal sensitivity in a hemianopic visual field can be improved by long-term training using flicker stimulation
Temporal sensitivity in a hemianopic visual field can be improved by long-term training using flicker stimulation
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DOI：
10.1136/jnnp.2006.099366
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发表时间：
2007-01-01
影响因子：
11
通讯作者：
Nasanen, R.
中科院分区：
文献类型：
--
作者：
Raninen, A.;Vanni, S.;Nasanen, R.
背景：视觉半视野失明(偏盲)是视交叉后脑部损害的常见症状。虽然偏盲严重限制了日常生活活动，但目前的临床实践中还没有对盲侧视功能进行训练。目的：探讨强化训练能否提高盲侧视功能，以及闪光刺激训练是否能引起皮层反应的改变。他们在一年中每周两次接受30度闪光刺激或10度偏心闪光字母的训练，之后继续接受更多周边刺激的训练。每隔1~2个月记录一次脑磁反应，并在训练前、训练中和训练后记录Goldmann视野。结果：1名受试者偏心30度以内，另一名受试者偏心20度时，盲侧视野闪光敏感度提高到正常半视野水平。在盲区和完好区，闪烁的字母在偏心10度处都能被识别出来。改善范围从刺激水平经络扩展到30度以内的整个半盲视野。训练前，神经磁学记录显示，偏盲一侧在噪声水平以上没有信号。在训练期间，两名参与者都出现了诱发磁场。讨论：结果表明，在刺激区域，对闪光的敏感性可以完全恢复，敏感性的提高扩散到周围的神经元网络，并且在训练过程中，神经磁场发生了伴随的变化。
Background: Blindness of a visual half-field (hemianopia) is a common symptom after postchiasmatic cerebral lesions. Although hemianopia severely limits activities of daily life, current clinical practice comprises no training of visual functions in the blind hemifield.Objective: To find out whether flicker sensitivity in the blind hemifield can be improved with intensive training, and whether training with flicker stimulation can evoke changes in cortical responsiveness.Methods: Two men with homonymous hemianopia participated in the experiments. They trained with flicker stimuli at 30 degrees or with flickering letters at 10 eccentricity twice a week for a year, and continued training with more peripheral stimuli thereafter. Neuromagnetic responses were registered at 1-2-month intervals, and the Goldmann perimetry was recorded before, during and after training.Results: Flicker sensitivity in the blind hemifield improved to the level of the intact hemifield within 30 degrees eccentricity in one participant and 20 degrees eccentricity in the other. Flickering letters were recognised equally at 10 degrees eccentricity in the blind and intact hemifields. Improvement spread from the stimulated horizontal meridian to the whole hemianopic field within 30 degrees. Before training, neuromagnetic recordings showed no signal above the noise level in the hemianopic side. During training, evoked fields emerged in both participants. No changes were found in the Goldmann perimetry.Discussion: Results show that sensitivity to flicker could be fully restored in the stimulated region, that improvement in sensitivity spreads to the surrounding neuronal networks, and that, during training, accompanying changes occurred in the neuromagnetic fields.