Interactions between LIP and V4 during top-down visual attention

描述(申请人提供)：当人们面对日常拥挤的视觉场景时，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。一般认为，感觉信息的过滤进入更高水平的大脑过程是由后顶叶皮质(PPC)等区域自上而下的控制信号调节的。这项建议的目的是揭示PPC的一个细分区域，即外侧顶内区(LIP)使用的自上而下注意的机制。将采用系统水平的神经生理学方法来研究LIP和较早的腹侧视流视觉区域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中成对的同时记录来量化注意调制效应的时间过程和大小，以每个区域内和跨区域的放电率和局部场势(LFP)来测量。关于LIP在V4中驱动注意调节的作用，包括两个区域之间的功能耦合的作用，将检验几个假说。第二个目标将直接评估LIP在选择性视觉注意过程中对V4的因果影响，使用新的光遗传技术来沉默/激活LIP中的兴奋性神经元。首先，LIP将被暂时沉默，以移除LIP对V4的自上而下的注意反馈，直接抑制V4神经活动的注意调节，并损害行为表现。其次，LIP将被激活，以便直接将自上而下的注意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影响。了解嘴唇自上而下的注意机制的神经基础将有助于开发一种视觉假体来帮助严重视觉障碍的人。此外，利用光遗传学以毫秒级的精度操纵视觉系统中的细胞的能力有望显著提高用于视觉神经假体的下一代大脑刺激器的能力。 与公共健康相关：我们预计，该项目的成功实施将为自上而下控制注意力的机制带来新的见解，从而提高我们对中枢神经系统功能的理解，从而优化视力低下或失明的人的感知处理能力。此外，使用新的光遗传学工具通过以毫秒级的精度操纵细胞来探测注意回路，将有助于开发用于视觉假体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.