Impact of blindness onset on the functional organization and the connectivity of the occipital cortex
Impact of blindness onset on the functional organization and the connectivity of the occipital cortex
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DOI：
10.1093/brain/awt176
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发表时间：
2013-09-01
期刊：
影响因子：
14.5
通讯作者：
Lepore, Franco
中科院分区：
文献类型：
--
作者：
Collignon, Olivier;Dormal, Giulia;Lepore, Franco
对比先天性失明与晚发性后天失明的影响，提供了一个独特的模型来探索不同发育时期的经验如何塑造枕叶皮质的功能组织。我们使用功能性磁共振成像来表征先天性失明、晚发性失明和两组视力正常的对照个体在处理声音的音高或空间属性时的大脑激活。而两个盲人组招募枕区的声音处理，活动在双侧楔是唯一明显的先天性失明，突出存在特定区域的关键时期的跨模态可塑性。最重要的是，右背侧流（中枕回和楔叶）的优先激活的空间处理的声音只观察到先天性失明。这表明，视觉必须在早期敏感期丧失，以便将其空间处理的功能专业化转移到非视觉模态。然后，我们使用动态因果模型与贝叶斯模型选择相结合，以证明初级视觉皮层中的视觉驱动活动可以更好地解释为与先天性失明的初级听觉皮层的直接联系，而它更多地依赖于晚发性失明组的顶叶区域的反馈输入。两者合计，这些结果表明视觉剥夺的发展时期（重新）塑造的功能架构和枕叶皮层的连通性的关键作用。这些发现在临床上很重要，因为越来越多的医疗干预可能会在视觉剥夺一段时间后恢复视力。
Contrasting the impact of congenital versus late-onset acquired blindness provides a unique model to probe how experience at different developmental periods shapes the functional organization of the occipital cortex. We used functional magnetic resonance imaging to characterize brain activations of congenitally blind, late-onset blind and two groups of sighted control individuals while they processed either the pitch or the spatial attributes of sounds. Whereas both blind groups recruited occipital regions for sound processing, activity in bilateral cuneus was only apparent in the congenitally blind, highlighting the existence of region-specific critical periods for crossmodal plasticity. Most importantly, the preferential activation of the right dorsal stream (middle occipital gyrus and cuneus) for the spatial processing of sounds was only observed in the congenitally blind. This demonstrates that vision has to be lost during an early sensitive period in order to transfer its functional specialization for space processing toward a non-visual modality. We then used a combination of dynamic causal modelling with Bayesian model selection to demonstrate that auditory-driven activity in primary visual cortex is better explained by direct connections with primary auditory cortex in the congenitally blind whereas it relies more on feedback inputs from parietal regions in the late-onset blind group. Taken together, these results demonstrate the crucial role of the developmental period of visual deprivation in (re)shaping the functional architecture and the connectivity of the occipital cortex. Such findings are clinically important now that a growing number of medical interventions may restore vision after a period of visual deprivation.