Neural Mechanisms of Selective Visual Attention

描述(申请人提供)：当人们面对一个典型的拥挤的视觉场景时，需要注意机制来将视觉处理限制在当前与行为相关的对象上。对这些注意力机制的了解最终将有助于为有严重视觉障碍的人开发视觉假体，也将有助于开发治疗包括ADHD在内的影响注意力的大脑疾病的方法。这一提议的长期目标不仅是揭示注意力对大脑视觉处理的影响，而且还希望了解这些影响发生的神经机制。我们的重点放在视觉区域V1、V2和V4上，它们是皮层通路中最早的处理阶段之一，对物体识别很重要。新的结果表明，偏向于行为相关刺激的注意偏差可能不仅涉及神经元平均放电频率的变化，还涉及不同皮质层神经活动的时间安排。第一个具体目标是确定空间定向注意对V4细胞群体中尖峰时间的影响，并将这些影响与特定的视觉引导行为联系起来。下一个目标是区分空间定向注意对V1、V2和V4区浅层和深层细胞的影响。第三个目标是建立空间定向注意对从V1到V4区域的视觉通路的影响序列。该研究计划的中心假设是，自上而下的注意机制不仅导致纹外皮质反应的放电频率和时间同步性的变化，而且这些对神经活动的注意效应具有功能相关性，并且这些变化是以从高阶区到低阶区的“反向”方向传递的。这些假设测试了新的想法，但它们得到了初步数据的很好支持，而且我们有很好的条件来测试它们，因为我们已经有了多年的技术经验。

DESCRIPTION (provided by applicant): When people are confronted by a typical, crowded visual scene, attentional mechanisms are needed to limit visual processing to objects that are currently relevant to behavior. An understanding of these attentional mechanisms will ultimately help in developing a visual prosthesis for people with severe visual impairments, and will also help in developing treatments for people with brain disorders affecting attention, including ADHD. The long term goal of this proposal is to not only uncover attentional influences on visual processing in the brain but also to understand the neuronal mechanisms by which these effects occur. Our focus is on visual areas V1, V2, and V4, which are among the earliest processing stages in the cortical pathway important for object recognition. New results suggest that the attentional bias in favor of behaviorally relevant stimuli may involve not only changes in the average firing rate of neurons but also the timing of neural activity in different cortical layers. The first specific aim is to identify the effects of spatially-directed attention on the timing of spikes in populations of cells in V4, and relate these effects to specific visually- guided behaviors. The next aim is to differentiate the effects of spatially directed attention on cells in the superficial versus deep lamina of areas V1, V2, and V4. The third aim is to establish the sequence of the effects of spatially directed attention on the visual pathway extending from V1 through area V4. The central hypotheses of the research program are that top-down attentional mechanisms induce changes in not only the firing rate but also the temporal synchrony of responses in extrastriate cortex, that these attentional effects on neural activity have functional correlates, and that these changes are relayed in a "backward" direction from higher order areas to lower order ones. These hypotheses test novel ideas, but they are well supported by preliminary data, and we are well-positioned to test them since we have had many years of experience with the techniques.