NEUROMAGNETIC MAPPING OF MULTIPLE VISUAL AREAS IN HUMANS

人类大脑活动的非侵入性磁记录是 结合解剖MRI和数学模型， 电磁源估计调查的位置和 人类大脑皮层中多个视觉区域的排列， 其功能特点。期间获得的结果 前一个项目期间表明，选择性操纵 视觉刺激特性（例如，颜色和亮度）可以 优先激活人体内的来源， “腹侧”与“背侧”处理流在非- 人类灵长类动物（Ungerleider和Mishkin，1982）。这些结果 在特定的感受域框架内进行解释 与这两个流相关的属性。激活区域 由等亮度色刺激引起的局部化到外侧 舌回和梭状回;在非人类灵长类动物研究中， 梭状回被证明包含广泛的代表 对中央视野敏感，并优先对 颜色.本申请通过聚焦于以下方面来扩展先前的工作： 活动与背流的处理， 有助于空间视觉。外围字段位置将 通过呈现小的圆形正弦刺激（“靶心”）来评估 模式）到上/下和左/右的3个偏心率 视野自动化源定位程序将 应用于这些神经磁测量来识别和定位 对这些刺激做出反应的结构。功能 背流中结构的表征将是 通过以下方式评估：1）操纵 构成圆形的白色/灰色带之间的交替 正弦曲线和2）通过操纵红色/绿色和 灰色/白色条带似乎向外移动（扩展 运动）。在某些情况下，运动的感知将是 通过调整红色/绿色波段的强度， 均衡感知亮度。本项目的长期目标 是对特定信息处理途径的描绘， 人类的大脑通过以下方式获得的方法和知识 不同视觉区域的功能表征将 最终有助于更好地理解更高的认知 功能协调发展的

Noninvasive magnetic recordings of human brain activity are combined with anatomical MRI and mathematical models for electromagnetic source estimation to investigate the locations and arrangement of multiple visual areas in human cortex and to probe their functional characteristics. Results obtained during the preceding project period suggest that selective manipulation of visual stimulus properties (e.g., color and luminance) can preferentially activate sources in humans consistent with the "ventral" versus "dorsal" processing streams identified in non- human primates (Ungerleider and Mishkin, 1982). These results have been interpreted within a framework of the specific receptive field properties associated with these two streams. Regions of activation evoked by isoluminant chromatic stimuli were localized to lateral lingual and fusiform gyri; in nonhuman primate studies, the fusiform gyrus has been shown to contain extensive representations of the central visual field and to be preferentially sensitive to color. The present application extends previous work by focusing on activity associated with the dorsal stream of processing, which subserves spatial vision. Peripheral field locations will be assessed by presenting small circular sinusoid stimuli ("bulls-eye" patterns) to 3 eccentricities in the upper/lower and left/right visual fields. Automated source localization procedures will be applied to these neuromagnetic measures to identify and localize the structures responsive to these stimuli. Functional characterization of structures in the dorsal stream will be assessed by: 1) manipulating the temporal frequencies of alternation between white/gray bands comprising the circular sinusoids and 2) by manipulating the speed at which red/green and gray/white bands appear to move in an outward direction (expanding motion). In some conditions, the perception of motion will be "nulled" by adjusting the intensity of the red/green bands to equalize perceptual luminance. The long term goal of this project is the delineation of specific information processing pathways in the human brain. The methods and knowledge achieved through functional characterization of the different visual areas will ultimately aid in better understanding of higher cognitive functions.