Interactions between LIP and V4 during top-down visual attention

描述（由申请人提供）：当人们面对日常拥挤的视觉场景时，需要注意力机制将视觉处理限制在当前与行为相关的对象上。一般认为，将感觉信息过滤到更高层次的大脑过程是由后顶叶皮层（PPC）等区域的自上而下的控制信号调节的。本研究的目的是揭示PPC的一个分支--外侧顶内区（LIP）所采用的自上而下的注意机制。一个系统水平的神经生理学方法将被用来研究LIP和早期腹侧流视觉区V4之间的自上而下的相互作用。我们的第一个目标是利用LIP和V4中的配对，同时记录来量化每个区域和跨区域内的放电率和局部场电位（LFP）中测量的注意力调节效应的时间过程和幅度。几个假设将被测试有关LIP的作用，驱动注意力调制V4，包括两个领域之间的功能耦合的作用。第二个目标将直接评估LIP在选择性视觉注意期间对V4的因果影响，使用新颖的光遗传学技术来沉默/激活LIP中的兴奋性神经元。首先，LIP将暂时沉默，以从LIP中移除对V4的自上而下的注意反馈，直接抑制V4中神经活动的注意调制并损害行为表现。第二，LIP将被激活，以便直接将自上而下的注意力反馈偏向特定的刺激位置，同时测试对相关V4神经元、跨区域同步性和行为的结果效应。理解LIP中自上而下注意机制的神经基础将有助于开发视觉假体来帮助严重视觉障碍的人。此外，使用光遗传学以毫秒级精度操纵视觉系统中细胞的能力有望显着提高用于视觉神经假体的下一代脑刺激器的能力。 公共卫生相关性：我们期望该项目的成功实施将对自上而下控制注意力的机制产生新的见解，这将提高我们对中枢神经系统功能的理解，以优化低视力或失明患者的感知处理能力。此外，使用新型光遗传学工具通过以毫秒级精度操纵细胞来探测注意力回路，将有助于开发用于视觉修复的先进神经刺激方法。

DESCRIPTION (provided by applicant): When people are confronted by an everyday, crowded visual scene, attentional mechanisms are needed to restrict visual processing to objects that are currently relevant to behavior. It is generally believed that the filtering of sensory information into higher level brain processes is regulated by top-down control signals in areas such as posterior parietal cortex (PPC). The goal of this proposal is to uncover the mechanisms of top- down attention employed by a subdivision of PPC, the lateral intraparietal area (LIP). A systems level neurophysiology approach will be taken to investigate the top-down interactions between LIP and an earlier ventral stream visual area, V4. Our first aim will utilize paired, simultaneous recordings in LIP and V4 to quantify the timecourse and magnitude of attentional modulation effects measured in the firing rate and local field potential (LFP) within each area and across areas. Several hypotheses will be tested concerning LIP's role in driving attentional modulation in V4, including the role of functional coupling between the two areas. The second aim will directly assess LIP's causal influence on V4 during selective visual attention using novel optogenetic techniques to silence/activate excitatory neurons in LIP. First, LIP will be momentarily silenced to remove top-down attentional feedback to V4 from LIP, directly suppressing attentional modulation of neural activity in V4 and impairing behavioral performance. Second, LIP will be activated so as to directly bias top- down attentional feedback toward a particular stimulus location while testing the resultant effects on associated V4 neurons, cross-area synchrony and behavior. An understanding of the neural basis of top-down attentional mechanisms in LIP will aid in developing a visual prosthesis to assist people with severe visual impairments. Furthermore, the ability to manipulate cells in the visual system at millisecond precision using optogenetics promises to significantly advance the capabilities of next-generation brain stimulators used in visual neural prostheses. PUBLIC HEALTH RELEVANCE: We expect that the successful implementation of this project will yield new insights into the mechanisms of top- down control of attention that will improve our understanding of central nervous system function in order to optimize the perceptual processing capabilities of people with low vision or blindness. Moreover, the use of novel optogenetic tools to probe attentional circuits by manipulating cells with millisecond precision will aid in the development of advanced neuro-stimulation approaches for visual prosthetics.