Experimental and Biological Psychology, Philipps-University Marburg, Marburg, Germany.
Restor Neurol Neurosci. 2010;28(2):193-205. doi: 10.3233/RNN-2010-0500.
The dorsal stream has been proposed to compute vision for space perception and for the control of action. However, perceiving space and guiding movements is not only based on vision but also on other sensory modalities such as proprioception and kinesthesia. Blind people who lost vision early in life provide an exceptional example to study the plasticity of dorsal stream functions. Using fMRI and psychophysical methods, action control and space perception was investigated in congenitally blind and sighted adults while performing active and passive hand movements without visual feedback. The functional imaging data showed largely overlapping activation patterns for kinesthetically guided hand movements in congenitally blind and sighted participants covering regions of the dorsal stream. In contrast to the sighted participants, congenitally blind participants additionally activated the extrastriate cortex and the auditory cortex. The psychophysical results revealed a significant correlation between proprioceptive spatial discrimination acuity of the blind and the age when they had attended an orientation and mobility training, i.e., an extensive non-visual spatial training. The earlier the blind acquired such a spatial training the more accurate and the more precise was their space perception in later life. Our findings suggest a multisensory network of movement control that develops on the basis of sensorimotor feedback rather than being under the exclusive control of vision. Thus, visual deprivation seems to result in both cross-modal and compensatory intra-modal plasticity. The present findings further imply that dorsal stream functions are shaped by non-visual spatial information during early development.
背侧流被认为负责空间感知和动作控制。然而，感知空间和引导动作不仅基于视觉，还基于其他感觉模态，如本体感觉和运动感觉。早年失明的盲人提供了一个特殊的例子，可以研究背侧流功能的可塑性。使用 fMRI 和心理物理学方法，在进行无视觉反馈的主动和被动手部运动时，研究了先天性失明和视力正常的成年人的动作控制和空间感知。功能成像数据显示，在先天性失明和视力正常的参与者中，进行运动感觉引导的手部运动时，背侧流区域的激活模式大致重叠。与视力正常的参与者不同，先天性失明的参与者还激活了外纹状体皮层和听觉皮层。心理物理学结果表明，盲人的本体感觉空间辨别锐度与他们接受定向和行动训练（即广泛的非视觉空间训练）的年龄之间存在显著相关性。盲人越早接受这种空间训练，他们在以后的生活中空间感知的准确性和精确性就越高。我们的发现表明，运动控制是一个多感觉网络，它是基于感觉运动反馈发展的，而不是由视觉单独控制的。因此，视觉剥夺似乎导致了跨模态和补偿性的内模态可塑性。本研究结果进一步表明，背侧流功能在早期发育过程中受到非视觉空间信息的塑造。
