Developmental Orgins of Human Extrastriate Areas

描述(由申请人提供)：本提案是对PA-03-107(NIH探索/发展研究资助奖R21)的响应。过去十年来的功能磁共振成像研究已经相当详细地揭示了人类视觉皮质的功能组织，包括识别一些纹外区，每个纹外区对特定的视觉信息做出非常选择性的反应：面部的梭形面部区域(FFA)；场景的空间结构的副海马区(PPA)；身体及其部分的纹状体外体区(EBA)；对象形状的枕侧复合体(LOC)；以及视觉运动区MT。关于这些纹外区域的发育起源，人们几乎一无所知。这里描述的实验将首先对4岁-成人的儿童进行一系列视觉任务的行为测试，每个任务旨在利用不同纹状体外区域的功能，然后直接使用fMRI来表征这些纹状体外区域的发育(在7岁-成人儿童中)，最后测试从神经元观察到的发育变化与观察到的行为之间的关系。我们将测试这一假设，即皮质特化在整个童年期间都会增加(如果皮质通过经验进行微调，则如预期的那样)，与竞争的假设，即处理模块之间的信息交换随着发育而增加，从而减少这些区域中特定领域的激活模式。我们还将检验关于发展变化时间进程中地区之间差异的具体假设。最后，我们将通过对个别受试者的纵向研究，测试我们观察到的行为和神经发育变化之间的关系。纹外皮质是儿科功能磁共振成像的理想测试案例，因为来自大脑这一区域的大胆信号非常大，而且激活这一区域不需要复杂的任务。除了推进儿科功能磁共振成像的方法学外，这项工作还可能对以下问题提供重要的见解：1)人类纹状体外皮质区域的发育起源；2)每个区域所伴随的行为功能；3)儿童时期视觉形状表征的性质和发展变化；4)高级视觉及其神经底物的领域特异性。

DESCRIPTION (provided by applicant): This proposal is in response to PA-03-107 (NIH EXPLORATORY/DEVELOPMENTAL RESEARCH GRANT AWARD R21). FMRI investigations over the last decade have revealed the functional organization of human visual cortex in considerable detail, including the identification of a number of extrastriate areas, each of which responds quite selectively to a specific kind of visual information: the fusiform face area (FFA) for faces; the parahippocampal place area (PPA) for the spatial structure of scenes, the extrastriate body area (EBA) for bodies and their parts, the lateral occipital complex (LOC) for object shapes, and visual motion area MT. Almost nothing is known about the developmental origins of these extrastriate areas. The experiments described here will first behaviorally test children age 4-adult on a set of visual tasks, each designed to tap the function of a different extrastriate area, then characterize the development of these extrastriate regions directly using fMRI (in children age 7-adult), and finally test the relationship between the developmental changes observed neurally and those observed behaviorally. We will test the hypothesis that cortical specialization increases throughout childhood (as expected if the cortex is fine-tuned through experience), against the competing hypothesis that informational exchange between processing modules increases over development, thereby reducing domain-specific activation patterns in these areas. We will also test specific hypotheses about differences between areas in the time course of developmental change. Finally, we will test relationships between the developmental changes we observe behaviorally vs. neurally with longitudinal studies of individual subjects. Extrastriate cortex is an ideal test case for pediatric fMRI because BOLD signals are very large from this region of the brain, and because complex tasks are not required to activate this region. In addition to advancing the methodology of pediatric fMRI, this work is likely to provide important insights about i) the developmental origins of human extrastriate cortical areas, ii) the behavioral functions that each area subserves, iii) the nature and developmental change in visual shape representations across childhood, and iv) the domain-specificity of high-level vision and its neural substrate.