FUNCTIONAL BRAIN IMAGING STUDIES OF HUMAN VISUAL COGNITION

调节视觉感知、注意力和记忆的人类神经系统 在完整的大脑中进行了功能脑成像研究。 正电子发射断层扫描(PET)与功能磁共振 成像(Fmri)用于精确测量局部血流动力学。 与选定的视觉感知和性能相关的变化 助记任务。这些血流动力学变化是脑出血局部改变的指标。 神经活动。人类纹外视皮层，就像 猕猴，被发现被组织成腹侧物体视觉 流和背侧空间视觉流。腹侧皮质区 客体视觉路径表现出明显的功能特化 与颜色感知相关的区域，与 面和其他对象。不同类别的物体，如脸， 房屋和椅子，腹侧区域的不同激活 纹状体外皮质，这表明 定义类别的要素聚集在一起。因此，表示 视觉是从早期视觉中的视网膜组织转换而来的 腹侧纹状体外侧区的“对象性”表征 区域。完整的对象和空间视觉处理流， 包括纹状体外后部和前额叶投影，参与 在物体和空间视觉工作记忆中。不同的前额叶区域 与物体和空间视觉工作记忆有关。空间 工作记忆激活了额叶上沟中的一个区域 位于人类前部视野的前方。三，解剖学和 前额中部和下部功能明显不同的区域 额叶回参与客体工作记忆。

Human neural systems that mediate visual perception, attention, and memory were investigated in the intact brain with functional brain imaging. Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) were used to measure precisely localized hemodynamic changes associated with the performance of selected visual perceptual and mnemonic tasks. These hemodynamic changes are indices of local changes in neural activity. Human extrastriate visual cortex, like that of the macaque monkey, was found to be organized into a ventral object vision stream and a dorsal spatial vision stream. Cortical areas in the ventral object vision pathway demonstrated functional specialization with distinct areas associated with color perception as compared to the perception of faces and other objects. Different categories of objects, such as faces, houses, and chairs, differentially activate regions of ventral extrastriate cortex, suggesting that the neural representations of the features that define categories cluster together. Thus the representation of vision is converted from a retinotopic organization in early visual areas to an "objectopic" representation in later ventral extrastriate areas. The complete object and spatial visual processing streams, including posterior extrastriate and prefrontal projections, participate in object and spatial visual working memory. Different prefrontal areas were associated with object and spatial visual working memory. Spatial working memory activated a region in the superior frontal sulcus just anterior to the human frontal eye field. Three, anatomically and functionally distinct prefrontal regions in the middle and inferior frontal gyri were identified that participate in object working memory.