EVOLUTION OF HEMISPHERIC ASYMMETRIES IN PERCEPTION

感知中半球不对称的演变

• 批准号: 6186765
• 负责人: MICHAEL S GAZZANIGA
• 金额: $ 17.29万
• 依托单位: DARTMOUTH COLLEGE
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-06-01 至 2003-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6186765
• 关键词: brain interhemispheric activity; cerebral dominance; clinical research; evolution; form /pattern perception; human subject; language development; neural information processing; sensory discrimination; sequential perception; space perception; split brain; tachistoscope; temporal lobe /cortex; time perception; visual fields; visual perception; visual stimulus

It is commonly noted that the left hemisphere is specialized for language and related cognitive processes while the right hemisphere is specialized for visuospatial processes. In this proposal, we investigate the idea that specialization of function has an associated cost. As each hemisphere becomes increasingly specialized for particular functions, we hypothesize that cortical regions are co-opted for these burgeoning functions. Since these co-opted cortical regions were previously performing some other function, that function will necessarily be adversely affected by the loss of cortex devoted to it. We hypothesize that this cost will be in higher-level perceptual functions, because lower-level perceptual functions are required by both hemispheres, and should be bilaterally represented. We hypothesize that the costs associated with hemispheric specialization are predictable. It has been hypothesized that the development of language in the left hemisphere is predicated on its relative superiority for temporal and sequential processing. We argue that this asymmetry "snowballed" over the course of human evolution, resulting in increasing specialization for timing and sequencing in the left hemisphere. This, in turn, resulted in a loss of visuospatial grain in the left hemisphere as tissue previously devoted to this function was co-opted for language. Relieved of the necessity of making such discriminations, we hypothesize that cortical resources previously dedicated to temporal processing in the right hemisphere were co-opted for fine-grained perceptual processing, effectively trading off temporal for spatial resolution. We propose to investigate the pattern of hemispheric specializations for perceptual abilities and their associated processing costs. Callosotomy ("split-brain") patients provide a unique opportunity to investigate the perceptual processes of each hemisphere in isolation. Although the notion of hemispheric specialization is not a new one, the idea that specialization has associated costs has implications for theories of brain function and for evolutionary theories of brain development.

人们通常注意到，左半球专门负责语言和相关的认知过程，而右半球专门负责视觉空间过程。在这个提议中，我们研究了功能专业化有相关成本的想法。随着每个半球的功能变得越来越专门化，我们假设皮质区域被这些新兴的功能所同化。由于这些增选的皮质区域以前执行一些其他功能，这些功能必然会受到专门用于该功能的皮质丧失的不利影响。我们假设这种代价将出现在更高层次的感知功能中，因为两个半球都需要较低层次的感知功能，并且应该被双侧表示。我们假设与半球专业化相关的成本是可预测的。据推测，语言在左半球的发展是基于其相对优势的时间和顺序处理。我们认为，这种不对称在人类进化过程中“滚雪球”，导致左半球对时间和排序的专业化程度不断提高。这反过来又导致了左半球视觉空间颗粒的丧失，因为先前用于该功能的组织被用于语言。由于没有必要进行这样的区分，我们假设以前专门用于右半球时间处理的皮质资源被用于细粒度的感知处理，有效地将时间分辨率与空间分辨率相交换。我们建议研究感知能力的半球专门化模式及其相关的加工成本。胼胝体切开术（“裂脑”）患者提供了一个独特的机会来研究孤立的每个半球的感知过程。尽管半球特化的概念并不是一个新概念，但特化有相关成本的想法对大脑功能理论和大脑发育的进化理论有影响。