EVOLUTION OF HEMISPHERIC ASYMMETRIES IN PERCEPTION

感知中半球不对称的演变

• 批准号: 2839204
• 负责人: MICHAEL S GAZZANIGA
• 金额: $ 17.66万
• 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/2839204
• 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.

通常注意到，左半球专门用于语言和相关的认知过程，而右半球专门用于视觉空间过程。 在这个建议中，我们调查的想法，专业化的功能有一个相关的成本。 随着每个半球越来越专门用于特定的功能，我们假设皮质区域被选用于这些新兴的功能。由于这些被增选的皮层区域先前执行其他功能，该功能必然会受到专门用于该功能的皮层的损失的不利影响。我们假设，这种成本将在更高级别的知觉功能，因为较低级别的知觉功能需要由两个半球，应该是双边代表。 我们假设，与半球专业化相关的成本是可预测的。 有人假设左半球的语言发展是基于其在时间和顺序处理方面的相对优势。 我们认为，这种不对称性在人类进化过程中“滚雪球”，导致左半球的时间和顺序越来越专业化。 这反过来又导致了左半球视觉空间颗粒的损失，因为以前专门用于这种功能的组织被用于语言。 免除了进行这种区分的必要性，我们假设，以前专门用于右半球时间处理的皮质资源被增选用于细粒度的感知处理，有效地权衡时间和空间分辨率。 我们建议调查的模式半球的知觉能力和相关的处理成本的专业化。胼胝体切开术（“裂脑”）患者提供了一个独特的机会，以调查孤立的每个半球的知觉过程。 虽然大脑半球的专门化并不是一个新概念，但专门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都有影响。