FUNCTIONAL BRAIN IMAGING STUDIES OF HUMAN VISUAL COGNITION

利用功能性脑成像在完整脑中研究了调节视觉感知、注意力和记忆的人类神经系统。正电子发射断层扫描（PET）和功能性磁共振成像（fMRI）被用来测量与选定的视觉感知和记忆任务的性能相关的精确定位的血流动力学变化。这些血流动力学变化是神经活动局部变化的指标。人类的纹外视皮层，像猕猴一样，被发现被组织成腹侧物体视觉流和背侧空间视觉流。腹侧物体视觉通路中的皮层区域表现出与颜色感知相关的不同区域的功能专业化，与面部和其他物体的感知相比。不同类别的物体，如脸、房子和椅子，会不同程度地激活腹侧纹外皮层区域，这表明定义类别的特征的神经表征聚集在一起。因此，视觉的表征从早期视觉区的retinotopic组织转换为后来腹侧纹外区的客观表征。完整的物体和空间视觉加工流，包括后部纹外投射和前额叶投射，参与物体和空间视觉工作记忆。不同的前额叶区域与物体和空间视觉工作记忆相关。空间工作记忆激活了上级额沟中的一个区域，就在人类额叶视野的前面。三，在解剖学和功能上不同的前额叶区域中，额下回被确定参与对象的工作记忆。- 视觉感知，注意力，记忆，PET，fMRI，-人类受试者

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. - Visual Perception, Attention, Memory, PET, fMRI, - Human Subjects