Functional connectivity in primary visual cortex

描述(由申请人提供)：准确的视觉皮质功能模型需要对视觉刺激如何在皮质内表示以及在该表示中涉及的特定回路有精确的了解。这些知识不仅对理解大脑中的视觉处理很重要，而且对未来使用皮质假体也是必不可少的，这种假体可以通过电微刺激为盲人提供视觉。在过去的几年里，人们一直在努力研究线方向和视觉空间是如何在初级视觉皮质内映射的，以及这些表征是如何通过不同类型的皮质内连接(水平连接、反馈连接和局部皮质内连接)联系在一起的。然而，膝状体皮质连接的等值测量仍然缺乏。这一认识上的差距是非常显著的，因为膝状体皮质连接是视觉信息进入大脑的主要入口，它们的功能组织与视觉空间的皮质表征密切相关。缺乏这些数据，目前的皮质功能模型使用了非常不同的膝状体皮质连接模式，从假设传入的随机分布到假设膝状感受区沿着每个皮质区域的首选方向整齐排列的模式。在这项提案中，我们将使用多电极记录、光学成像和神经元示踪技术的新的、强大的组合来填补这一重要的知识空白，并为皮质功能模型提供新的实验约束。我们的实验将揭示膝状体皮质通路在亚毫米尺度上的组织，以及这种微组织在大脑皮层内线方向和视觉空间表示中的作用。此外，我们还将研究膝状体皮质通路在没有视觉刺激的情况下定向结构域自发激活中的作用。拟议的实验结果将有助于揭示皮质处理的机制，这些机制可能在未来用于预防和治疗不同形式的中枢视觉障碍。

DESCRIPTION (provided by applicant): Accurate models of visual cortical function require a precise knowledge of how visual stimuli are represented within the cortex and the specific circuits that are involved in this representation. This knowledge is not only important to understand visual processing in the brain but it is also essential for the use of future cortical prosthesis that could provide vision to the blind through electrical microstimulation. Over the past years, there has been a great effort to investigate how line orientation and visual space are mapped within the primary visual cortex and how these representations are linked by different types of intracortical connections (horizontal connections, feedback connections and local intracortical connections). However, the equivalent measurements for geniculocortical connections are still missing. This gap in our knowledge is very significant because the geniculocortical connections are the main entrance of visual information to the brain and their functional organization is intimately related with the cortical representation of visual space. Lacking these data, current models of cortical function use very different patterns of geniculocortical connectivity, from those that assume a random distribution of the afferents to those that assume a neat alignment of the geniculate receptive fields along the preferred orientation of each cortical domain. In this proposal, we will use a new, powerful combination of multielectrode recording, optical imaging and neuronal tracer techniques to fill this important gap in knowledge and provide new experimental constraints to models of cortical function. Our experiments will reveal the organization of the geniculocortical pathway at the submillimeter scale and the role of this micro-organization in the representation of line orientation and visual space within the cortex. In addition, we will investigate the role of the geniculocortical pathway in the spontaneous activation of orientation domains in the absence of visual stimuli. The results of the proposed experiments will help to uncover mechanisms of cortical processing that could be used in the future to prevent and treat different forms of central visual disorders.