fMRI and Behavioral Analyses of the Representation of Shape

形状表征的功能磁共振成像和行为分析

• 批准号: 0531177
• 负责人: Irving Biederman
• 金额: $ 20万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0531177&HistoricalAwards=false
• 关键词: fMRI; Behavioral; Analyses; Representation; Shape

In a fraction of a second, an image of an object or scene--one never experienced previously--can be easily comprehended by a human observer. The functional magnetic resonance imaging (fMRI) study of the neural basis of this remarkable feat has been greatly advanced by the discovery of a cortical area that responds well to intact objects but not to scrambled versions of these same images. This region, termed "the lateral occipital complex" (LOC), runs ventrally from the occipital lobe to the posterior regions of the temporal lobe. LOC is not merely activated by familiar objects in that unfamiliar objects, such as abstract sculptures, also produced greater activation in LOC compared to their scrambled versions. Nor is activation in LOC merely a feed forward effect from earlier visual stages in that these stages show greater activation for the scrambled compared to the intact versions of the images. LOC responds equivalently to a photograph and a line drawing of the same object. Bilateral lesions to LOC have been shown to produce a complete inability to recognize objects on the basis of their shape, while leaving visually guided motor interactions unaffected. LOC thus represents physical shape to which, presumably, semantic information, including a name, can be associated. This stage thus appears to be at the threshold of cognition. Despite the advances enabled by the LOC localizer, there is considerable uncertainty as what this localizer is actually localizing. The scrambling operation affects both low-level measures of the image as well as higher-level aspects associated with the interpretation of the object. The low-level measures include an increase in the extent of the display produced by the scattering of the elements, a loss of low frequency information, and a marked increase in the clumps from one (the intact object) to over 20. Of course, with the scattering, the sizes of the clumps are similarly reduced. With National Science Foundation funding, Dr. Irving Biederman will conduct fMRI research designed to clarify just what the localizer is localizing and in doing so, provide some clues as to how shape is abstracted from an image. The research would elucidate the neural coding of object vs. texture, the effect of the number of elements in a display and whether these elements comprise an intact object or scene. Additionally, attention will be paid toward defining those cortical areas that might be more responsive to aspects, such as texture rather than object, in the scrambled images.The immediate broader impacts will be to contribute to advancing our knowledge as to the neural representation of shape for purposes of recognition. The research will fill a critical gap between psychophysical (behavioral) research on object recognition and single-unit recording of shape variations in the macaque. Although the homologues between human and macaque of primary sensory and motor cortices are well established there are significant questions concerning the homologues of later, perceptual "association" areas. Extensive plans are already in place for an outreach program involving USC's NSF-funded 3T scanner. Because of the accessibility of the problem of real-time object recognition to a non-technically advanced audience, this research will be one of the featured research projects for exposing cognitive neuroscience to students from USC's largely minority neighborhood and to recruit some to participate in the research itself.

在几分之一秒的时间里，一个物体或场景的图像--一个以前从未经历过的图像--可以很容易地被人类观察者理解。 功能性磁共振成像（fMRI）对这一非凡壮举的神经基础的研究已经大大推进，因为发现了一个皮层区域，它对完整的物体反应良好，但对这些相同图像的混乱版本反应不佳。这一区域被称为“枕叶外侧复合体”（lateral occipital complex，缩写为EMPL），从枕叶腹侧延伸至颞叶后部。 不熟悉的物体，如抽象雕塑，不仅会激活大脑，而且与它们的杂乱版本相比，也会产生更大的激活。大脑中的激活也不仅仅是来自早期视觉阶段的前馈效应，因为与完整版本的图像相比，这些阶段显示出更大的激活。它相当于同一物体的照片和线条画。 研究表明，双侧脊髓损伤会导致完全无法根据物体的形状识别物体，而视觉引导的运动相互作用不受影响。因此，它表示物理形状，可能与语义信息（包括名称）相关联。 因此，这个阶段似乎处于认知的门槛。 尽管有了这些进步，但这个定位器实际上是在定位什么，还存在相当大的不确定性。加扰操作既影响图像的低级测量，也影响与对象的解释相关联的高级方面。 低水平的措施包括增加的范围内产生的元素的散射显示，低频信息的损失，并显着增加的团块从一个（完整的对象）到超过20。 当然，随着散射，团块的大小也会类似地减小。在国家科学基金会的资助下，欧文·比德曼博士将进行功能磁共振成像研究，旨在澄清定位器定位的是什么，并在此过程中提供一些关于形状如何从图像中抽象出来的线索。 这项研究将阐明对象与纹理的神经编码，显示器中元素数量的影响以及这些元素是否构成完整的对象或场景。 此外，我们还将注意力集中在定义那些可能对杂乱图像中的纹理（而不是物体）更敏感的皮层区域上，其直接的更广泛的影响将有助于推进我们对用于识别目的的形状的神经表征的知识。 这项研究将填补心理物理学（行为）研究之间的一个关键空白物体识别和单单位记录形状变化的猕猴。 虽然人类和猕猴的初级感觉和运动皮层之间的同源物已经很好地建立，但关于后来的知觉“联想”区域的同源物仍存在重大问题。 广泛的计划已经到位，涉及南加州大学的NSF资助的3 T扫描仪的推广计划。 由于实时对象识别问题对非技术先进的受众的可访问性，这项研究将成为将认知神经科学暴露给南加州大学主要少数民族社区学生的特色研究项目之一，并招募一些人参与研究本身。