北京大学心理学系和机器感知与智能教育部重点实验室,香港大学心理学系,明尼苏达州大学的研究人员利用功能性核磁共振技术研究视皮层可塑性取得的新进展。这一研究成果公布在Current Biology杂志上。
人类通过多个感觉通道接受外界信息,包括视觉、听觉、触觉、嗅觉等。这些信息被大脑整合、解释以达到还原外部世界的目的。各个通道之间不仅存在合作,也存在竞争,比如早期研究发现盲人的“视”皮层被用于加工触觉信息。
在这篇文章中,研究人员报道了一个特殊病人的个案研究,该病人由于眼球病变而导致弱视,只能看见低频空间信息(模糊信息),而看不见高频空间信息(精确信息),但他的触觉能力远超正常人,可以快速准确的阅读盲文和精确识别触觉刺激。利用功能性核磁共振扫描该病人的大脑,发现他的视皮层中对应外周视野的区域被用来加工视觉信息,而对应中央视野的区域被用来加工触觉信息。一般认为,对应外周视野的视觉区被用来加工低频模糊信息,而对应中央视野的视觉区被用来加工高频精确信息。由于该病人看不见高频空间信息,他的大脑中对应中央视野的视觉区就被触觉加工“占用”了。视皮层的这种特异性重组反映了,大脑可以适应性的利用有限的神经资源,对多模态信息进行高效处理。这对于理解皮层可塑性有重要意义,同时对于弱视病人的治疗与康复也有重要指导意义和临床借鉴意义。(生物谷Bioon.com)
生物谷推荐原始出处:
Current Biology,09 April 2009 doi:10.1016/j.cub.2009.02.063
Retinotopically Specific Reorganization of Visual Cortex for Tactile Pattern Recognition
Sing-Hang Cheung1,2,4,,,Fang Fang3,4,,,Sheng He2andGordon E. Legge2
1 Department of Psychology, The University of Hong Kong, Hong Kong, China
2 Department of Psychology, University of Minnesota, Minneapolis, MN 55455, USA
3 Department of Psychology and Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing 100871, China
4 These authors contributed equally to this work
Summary
Although previous studies have shown that Braille reading and other tactile discrimination tasks activate the visual cortex of blind and sighted people [1,2,3,4,5], it is not known whether this kind of crossmodal reorganization is influenced by retinotopic organization. We have addressed this question by studying S, a visually impaired adult with the rare ability to read print visually and Braille by touch. S had normal visual development until 6 years of age, and thereafter severe acuity reduction due to corneal opacification, but no evidence of visual-field loss. Functional magnetic resonance imaging revealed that, in S's early visual areas, tactile information processing activated what would be the foveal representation for normally sighted individuals, and visual information processing activated what would be the peripheral representation. Control experiments showed that this activation pattern was not due to visual imagery. S's high-level visual areas, which correspond to shape- and object-selective areas in normally sighted individuals, were activated by both visual and tactile stimuli. The retinotopically specific reorganization in early visual areas suggests an efficient redistribution of neural resources in the visual cortex.