Functional Brain Imaging Studies Of Human Visual Cogniti

人类调节视觉感知、注意力和记忆的神经系统在完整的大脑中进行了功能脑成像研究。功能磁共振成像(FMRI)被用来精确测量与选定的视觉、知觉和助记任务的执行相关的局部血流动力学变化。这些血流动力学变化是神经活动局部变化的指标。像猕猴一样，人类纹外视皮层被组织成腹侧客体视流和背侧空间视流。腹侧物体视觉通路被发现有一个功能结构，可以对不同类别的物体，如房屋、椅子、动物和工具产生不同的反应模式。这些与类别相关的反应模式在不同的受试者中非常一致。研究发现，面孔知觉既涉及更多地参与面孔身份表征的腹侧颞叶皮质，也涉及更多地参与表征面部形态变化的方面，如表情和眼神凝视方向。完整的客体和空间视觉加工流，包括纹外后部和前额叶投射，参与客体和空间视觉工作记忆。不同的前额叶区域与客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，该区域恰好位于人类额叶视野的前面。三、在额叶中、下回中、下回中、下额叶各有不同的解剖学和功能区，参与客体工作记忆。事件相关功能磁共振被用来区分工作记忆中跟踪项目的互补机制-一种用于跟踪项目的重复，以便于忽略分心因素，另一种用于跟踪工作记忆搜索的目标。

Human neural systems that mediate visual perception, attention, and memory were investigated in the intact brain with functional brain imaging. Functional magnetic resonance imaging (fMRI) was 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, is organized into a ventral object vision stream and a dorsal spatial vision stream. The ventral object vision pathway was found to have a functional architecture that produces different patterns of response for faces and different categories of objects, such as houses, chairs, animals, and tools. These category-related patterns of response are remarkably consistent across subjects. Face perception was found to involve both the ventral temporal cortex, which is more involved in the representation of face identity, and the superior temporal sulcus, which is more involved in the representation of changeable aspects of the facial configuration that are important for social communincation, such as expression and eye gaze direction. 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. Event-related fMRI was used to distinguish complementary mechanisms for tracking items in working memory - one for tracking repetitions of items to facilitate ignoring distracters and one for tracking the target of a working memory search.