Raninen A, Vanni S, Hyvärinen L, Näsänen R
Department of Bio and Environmental Sciences, Physiology, Biocentre 3, PO Box 65, University of Helsinki, FI-00014, Finland.
J Neurol Neurosurg Psychiatry. 2007 Jan;78(1):66-73. doi: 10.1136/jnnp.2006.099366. Epub 2006 Sep 4.
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.
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.
Two men with homonymous hemianopia participated in the experiments. They trained with flicker stimuli at 30 degrees or with flickering letters at 10 degrees 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.
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.
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.
视交叉后脑部病变后，半侧视野失明（偏盲）是一种常见症状。尽管偏盲严重限制了日常生活活动，但目前的临床实践中并未对盲侧视野的视觉功能进行训练。
探究通过强化训练能否提高盲侧视野的闪烁敏感度，以及闪烁刺激训练是否能引起皮质反应性的变化。
两名患有同向性偏盲的男性参与了实验。他们每周两次接受30度的闪烁刺激或10度偏心度的闪烁字母训练，持续一年，之后继续使用更周边的刺激进行训练。每隔1 - 2个月记录一次神经磁反应，并在训练前、训练期间和训练后记录Goldmann视野检查结果。
一名参与者盲侧视野在30度偏心度范围内的闪烁敏感度提高到了与健侧视野相同的水平，另一名参与者则在20度偏心度范围内达到了相同效果。在10度偏心度时，盲侧和健侧视野对闪烁字母的识别能力相同。改善从受刺激的水平子午线扩展到30度范围内的整个偏盲视野。训练前，神经磁记录显示偏盲侧的信号未高于噪声水平。训练期间，两名参与者均出现了诱发电场。Goldmann视野检查未发现变化。
结果表明，受刺激区域对闪烁的敏感度可完全恢复，敏感度的提高会扩散到周围的神经网络，并且在训练期间，神经磁场会伴随发生变化。
