CEREBRAL MECHANISMS OF VISUAL FEATURE INTEGRATION

来自灵长类皮质的记录表明，视觉的不同特征 刺激在不同的皮质区域进行分析。感性的人是如何 系统重新组合这些特征以形成一致的感知？线索是 可从视觉搜索的研究中获得。受试者快速检测目标 与单一特征(例如，颜色)的干扰刺激不同，但 当通过连接来区分目标时，速度慢且容易出错 特征(例如，颜色和方向)。根据特雷斯曼的特征 整合理论，刺激的单一特征被自动处理 并且在不同的特征映射中并行。然而，视觉特征 集成(VFI)需要一个连续过程，在该过程中对象必须首先 在它们的功能可以通过注意绑定在一起之前进行本地化 扫描。 不幸的是，在Search中研究VFI的生理学是困难的 任务，因为实验者永远不能确定哪种刺激 受试者正在处理。一种新的范式，快速的连续视觉呈现 (RSVP)，允许研究VFI以逐个呈现刺激。四 提出了使用RSVP任务的实验。相比之下，五分之一的人 利用视觉搜索的实验也包括在内。在所有的实验中， 行为分析将与事件的多通道记录相结合- 相关脑电位(ERPs)。与心电活动相关的事件相关电位差异波 个体刺激特征的处理和特征集成 将被隔离，以深入了解本地化和时间安排 VHI。初步结果显示，ERP差异波与特征有关 额区和顶区的连接，潜伏期为200-250毫秒。 事件相关差谱(ERD)也将用于定位 与VFI相关的皮质活动。初步数据显示ERD变化 与右顶叶和枕叶的视觉特征加工有关 头皮。 在所有实验中，正常的行为和电生理结果 受试者将与局灶性皮质炎患者的数据进行比较 顶叶外侧、前额叶背外侧或 后上颞面。已经显示了这些区域的损伤 在视觉搜索任务中损害VFI。行为和电生理 来自正常受试者和患者的结果将被用于测试一个模型 不同的VFI手术定位于不同的皮质区域； 外顶叶皮质位置的“主地图”，扫描 由背外侧前额叶皮质控制的主图 由颞顶交界处控制的注意力扫描的孔径。

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.