The activity of V4 in free viewing visual search

描述（由申请人提供）：当观察自然世界时，灵长类动物使用跳眼运动来扫描环境并注视感兴趣的物体以获得最大的视觉处理。然而，由于视觉场景中有许多潜在的感兴趣的对象，选择一个扫视目标是至关重要的。选择一个眼球运动到一个特定的项目是基于一个地形图代表突出的世界。侧顶叶内皮层（LIP）可能构建了这个显著性图，因为这个视觉运动区域可以定位与注视转移相关的行为对象，并投射到执行眼球运动的区域。然而，LIP缺乏必要的视觉形式处理，以根据其特征引导有目的的跳跃式行为。另一方面，V4作为能够选择扫视目标的视觉区域是一个很好的候选区域。它是一个负责物体处理的外层皮层，其活动与眼球运动相关，并将直接投影发送到LIP。因此，我们提出V4区域为LIP所代表的显著性地图提供视觉输入，该地图指导以自然视觉为特征的扫视模式。本实验的主要目的是表征V4神经元在自由观看视觉搜索时的生理反应特性，以更好地了解它们在更自然的视觉处理中所起的作用。我们设计了一个自由观看的视觉搜索任务，猴子可以完全自由地移动眼睛，并通过非目标手部运动来报告任务结果。我们将通过观察单个V4和LIP细胞记录的动眼肌行为和神经活动来研究以下3个目的：1)我们将描述V4神经元的跃前活动，以描述它们对指导后续扫视的贡献。2)我们将查看V4用于基于对象特征识别行为相关扫视目标的机制。3)我们将测试V4和LIP之间的连接功能。通过探索V4和LIP在同一任务中的关系，我们可以更好地理解视觉形式加工与眼动选择之间的联系，从而在自然视觉中最终定位搜索目标。健康相关性：患有顶骨和枕部病变的患者在视觉感知和产生眼球运动方面存在困难。通过了解正常功能视觉行为的生理基础，我们可以更好地诊断和设计这些患者的康复方案。

DESCRIPTION (provided by applicant): When viewing the natural world, primates use saccadic eye movements to scan the environment and fixate on objects of interest for maximal visual processing. However, since there are many potential objects of interest in the visual scene, choosing a saccade target is crucial. Selection of an eye movement to a particular item is based on a topographic map representing the salient world. Lateral intraparietal cortex (LIP) might construct this salience map since this visuomotor area can localize a behaviorally relevant object for a gaze shift and projects to areas involved in executing eye movements. However, LIP lacks the visual form processing necessary to guide purposeful saccadic behavior to a particular object based on its features. On the other hand, V4 is an excellent candidate as a visual area capable of selecting saccade targets. It is an extrastriate cortex responsible for object processing, has activity correlated to eye movements and sends direct projections to LIP. Thus, we propose that area V4 provides the visual input for the salience map represented in LIP which guides saccade patterns characterized by natural vision. The main objective of this experiment is to characterize the physiological response properties of V4 neurons during free viewing visual search to better understand the role they play in more natural visual processing. We designed a free viewing visual search task where monkeys are entirely free to move their eyes and report the results of the task by making a non-targeting hand movement. We will examine oculomotor behavior and neural activity recorded from single V4 and LIP cells while the monkeys perform this task to investigate the following 3 aims: 1) We will characterize the presaccadic activity of V4 neurons to describe their contribution to guiding subsequent saccades. 2) We will look at the mechanisms V4 uses to identify a behaviorally relevant saccade target based on object features. 3) We will test the function of the connection between V4 and LIP. By exploring the relationship between V4 and LIP in this identical task, we can understand better the link between visual form processing and selection of the eye movement to ultimately locate a search target during natural vision. HEALTH RELEVANCE: Patients with parietal and occipital lesions have difficulty in visual perception and generating eye movements. By understanding the physiology underlying normal functioning visual behavior, we can better diagnose and design rehabilitation programs for these patients.