Neurologisches Zentrum, St. Elisabeth-Krankenhaus Köln, Werthmannstr. 1c, Cologne, Germany.
J Neurol. 2010 Nov;257(11):1832-40. doi: 10.1007/s00415-010-5617-1. Epub 2010 Jun 10.
Changes in neuronal activity have been described in patients with hemianopia following ischemic lesions of the visual cortex. This reorganization may facilitate compensation of lost visual function that is rarely fully restituted. Improving exploratory eye movements with appropriate training has been shown to partially compensate for the visuoperceptive impairment during daily life activities. The changes in cortical processing of visual stimuli that may be induced by these training strategies, however, are less well described. We used fMRI to study the training effects of eye-movement training on cortical representation of visual hemifields. Brain activation during hemifield stimulation was measured in eight patients with an occipital cortical lesion of the striate cortex causing homonymous hemianopia. Starting 8 weeks after the stroke, patients received 4 weeks of eye movement training. fMRI measurements were performed at baseline and after training. In five patients, follow-up fMRI was performed 4 weeks after the end of training. Differences in activation between rest and hemifield stimulation as well as before and after training were assessed with statistical parametric mapping. Twelve healthy subjects were scanned twice at a 4-week interval. During stimulation of the affected hemifield, significant activation at baseline was found bilaterally in extrastriate cortical areas, with the strongest increases in the contralesional hemisphere. This activation pattern was maintained after training. Four weeks after the end of training, there was an additional activation of the extrastriate cortex in the contralesional hemisphere compared to baseline. No changes in the size of visual field defects were found. In this group of patients, eye-movement training induced altered brain activation in the unaffected extrastriate cortex.
已经描述了在视觉皮层缺血性病变后出现偏盲的患者中神经元活动的变化。这种重组可能有助于补偿很少能完全恢复的丧失的视觉功能。适当的训练已显示出改善探索性眼球运动，从而部分补偿日常生活活动中的视知觉障碍。但是，对于这些训练策略可能引起的视觉刺激皮质处理变化，描述得较少。我们使用 fMRI 研究眼球运动训练对视觉半视野皮质代表的训练效果。在 8 名由于纹状皮层的枕叶皮质病变而导致同侧偏盲的患者中测量了视野刺激期间的大脑激活。从中风后 8 周开始，患者接受了 4 周的眼球运动训练。在基线和训练后进行 fMRI 测量。在 5 名患者中，在训练结束后 4 周进行了后续 fMRI。使用统计参数映射评估了休息和视野刺激之间以及训练前后的激活差异。12 名健康受试者在 4 周的间隔内被扫描两次。在受影响的视野刺激期间，双侧在纹状体外皮质区域发现了明显的基线激活，对侧半球的增加最强。这种激活模式在训练后得以维持。在训练结束后 4 周，与基线相比，对侧半球的纹状体外皮质区域的激活增加。视野缺陷的大小没有变化。在这群患者中，眼球运动训练引起了未受影响的纹状体外皮质的大脑激活改变。
