CEREBRAL MECHANISMS OF VISUAL FEATURE INTEGRATION

灵长类动物大脑皮层的记录显示， 在不同的皮层区域中分析刺激。 知觉是如何 系统重新组合这些特征以形成一个连贯的概念？ 线索 从视觉搜索的研究中获得。 受试者快速检测目标 通过单个特征区别于分散注意力的刺激（例如，颜色），但 当目标被联合识别时， 特征（例如，颜色和方向）。 根据Treisman的特征， 整合理论，刺激的单个特征被自动处理 并且在不同的特征图中并行。 然而，视觉特征 集成（VFI）需要一个串行过程，其中对象必须首先被 在它们的特征被注意力结合在一起之前， 扫描. 不幸的是，很难研究VFI的生理学， 因为实验者永远无法确定哪种刺激会导致 目标正在处理。 一个新的范例，快速串行视觉呈现 （RSVP），允许VFI被研究的刺激呈现一个接一个。 四 实验提出了使用RSVP任务。 相比之下， 也包括利用视觉搜索的实验。 在所有实验中， 行为分析将与事件的多通道记录相结合， 相关脑电位（ERP）。 ERP差异波与 单个刺激特征的处理和特征整合 将被隔离，以提供对本地化和时间的洞察力， VHI。 初步结果表明，ERP差异波与特征有关， 在200-250毫秒的潜伏期，额叶和顶叶区域的连接。 事件相关差异谱（ERD）也将用于定位 与VFI相关的皮质活动。 初步数据显示， 与右顶叶和枕叶的视觉特征处理有关 头皮 在所有的实验中，行为和电生理结果从正常的 受试者将与来自局灶性皮质 顶叶外侧、背外侧前额叶皮质病变，或 后上级颞平面。 这些区域的病变 在视觉搜索任务中损害VFI。 行为和电生理 正常受试者和患者的结果将用于测试模型， 不同的VFI操作被定位到不同的皮层区域; 侧顶叶皮层位置的“主地图”， 由背外侧前额叶皮层控制的主地图 注意力扫描的孔径由颞/顶叶交界处控制。

Recordings from primate cortex have shown that different features of visual stimuli are analyzed in distinct cortical fields. How does the perceptual system recombine these features to form a coherent percept? Clues are available from studies of visual search . Subjects rapidly detect targets distinguished from distracting stimuli by single features (e.g., color) but are slow and error-prone when targets are distinguished by conjointed features (e.g., color and orientation). According to Treisman's feature integration theory, single features of stimuli are processed automatically and in parallel in different feature maps. However, visual feature integration (VFI) requires a serial process in which objects must first be localized before their features can be bound together by an attentional scan. Unfortunately, it is difficult to study the physiology of VFI in search tasks since the experimenter can never be certain which stimulus the subject is processing. A new paradigm, rapid serial visual presentation (RSVP), permits VFI to be studied for stimuli presented one-by-one. Four experiments are proposed using RSVP tasks. For comparison, a fifth experiment utilizing visual search is also included. In all experiments, behavioral analysis will be combined with multi-channel recording of event- related brain potentials (ERPs). ERP difference waves associated with the processing of individual stimulus features and with feature integration will be isolated to provide insight into the localization and timing of VHI. Preliminary results show ERP difference waves related to feature conjunction over frontal and parietal regions at latencies of 200-250 ms. Event-related difference spectra (ERDs) will also be used to localize cortical activity associated with VFI. Preliminary data show ERD changes related to visual feature processing over the right parietal and occipital scalp. In all experiments, behavioral and electrophysiological results from normal subjects will be compared with data from patients with focal cortical lesions of the lateral parietal lobe, dorsolateral prefrontal cortex, or posterior superior temporal plane. Lesions in the regions have been shown to impair VFI in visual search tasks. Behavioral and electrophysiological results from normal subjects and patients will be used to test a model in which different VFI operations are localized to distinct cortical regions; the "master map" of locations in lateral parietal cortex, the scan of the master map controlled by dorsolateral prefrontal cortex with a variable aperture of attentional scan controlled by the temporal/parietal junction.