NEUROMAGNETIC MAPPING OF MULTIPLE VISUAL AREAS

人类大脑活动的非侵入性磁性记录是 结合解剖MRI和数学模型 电磁源估计，以调查位置和 人脑皮质多个视区的排列及其探测 它们的功能特点。在调查期间取得的成果 之前的项目期表明，选择性地操纵 视觉刺激属性(例如，颜色和亮度)可以 优先激活人体内符合 “腹侧”与“背侧”处理流在非 人类灵长类(Ungerleider和Mishkin，1982)。这些结果产生了 在特定接受场的框架内被解释 与这两个流关联的属性。激活区 由同种发光体颜色刺激诱发的局部到侧方 舌回和梭形回；在非人灵长类动物研究中， 梭形回已被证明包含广泛的表征。 中心视野的位置，并优先对 颜色。本申请通过关注以下方面扩展了先前的工作 与加工的背侧流相关的活动，这 从属于空间视觉。外围现场位置将为 通过呈现小的圆形正弦刺激(“靶心”)进行评估 图案)到上/下和左/右的3个偏心 视野。自动化的源代码本地化程序将是 应用于这些神经磁学测量以识别和定位 对这些刺激做出反应的结构。功能性 背流中结构的特征将是 由以下方面评估：1)操纵时间频率 组成圆形的白色/灰色条带之间的交替 正弦和2)通过操纵红/绿和 灰色/白色条带似乎向外移动(扩展 动议)。在某些情况下，对运动的感知 通过将红色/绿色条带的强度调整为 使感知亮度均衡。这个项目的长期目标是 中对特定信息处理路径的描述 人类的大脑。通过以下途径获得的方法和知识 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。

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.