The role of GABAergic interneurons in mouse superior colliculus in visual processing and visually guided behaviours

视觉系统的核心任务是检测环境中与行为相关的物体，并引导适当的行为反应。中脑的上级丘（SC）接受来自视网膜神经节细胞的直接输入，并在视觉引导行为中起关键作用。更重要的是，上级丘内有高密度和多样性的抑制性神经元，这表明上级丘内的抑制性神经元在视觉处理中起着至关重要的作用。然而，不同类型的抑制性神经元如何在上级丘内塑造视觉信息的神经元表征，以及它们在视觉引导行为中的作用却知之甚少。本项目的主要目的是通过使用高密度电极的大规模电生理记录、细胞类型特异性识别和头固定小鼠中上级丘神经元的因果光遗传学扰动，结合先进的数据分析和计算建模，研究上级丘抑制性神经元的作用。为了理解上级丘中的抑制性神经元如何塑造视觉信息的表征，我们将（1）使用新开发的方法研究上级丘神经元如何在体内整合来自视网膜神经节细胞的输入，并通过光遗传学操作揭示抑制性SC神经元在视觉处理中的作用（2）。为了研究抑制性SC神经元在视觉引导行为中的作用，我们将（3）在视觉检测任务期间记录光遗传学识别的神经元的活动，并使用先进的数据分析研究视觉和行为信息如何在神经元群体的高维水平上表示。此外，为了测试对行为的因果作用，我们将在任务期间使用光遗传学操作来干扰抑制性神经元（4）。最后，我们将（5）将实验数据整合到上级丘视觉层的计算电路模型中，以研究相互作用的兴奋性和抑制性神经元如何整合和塑造视觉处理。因此，本项目的首要目标是研究上级丘的抑制性神经元如何在视觉加工过程中塑造群体活动，并揭示其在视觉引导行为中的因果作用。

A central task of the visual system is to detect behaviourally relevant objects in the environment and to guide appropriate behavioural responses. The superior colliculus (SC) in the midbrain receives direct inputs from the retinal ganglion cells and plays key roles in visually guided behaviours. Importantly, the superior colliculus houses a high density and large diversity of inhibitory neurons, suggesting a vital role of inhibitory neurons in visual processing in the superior colliculus. However, how different inhibitory neuron types sculpt the neuronal representation of visual information within the superior colliculus, and their role in visually guided behaviours is poorly understood. The main objective of this Project is to study the role of inhibitory neurons in superior colliculus through large-scale electrophysiological recordings using high-density electrodes, cell-type specific identification and causal optogenetic perturbation of superior colliculus neurons in head-fixed mice that preform a visually guided behavioural task, in combination with advanced data analysis and computational modelling. To understand how inhibitory neurons in the superior colliculus shape the representation of visual information we will (1) investigate how superior colliculus neurons integrate inputs from retinal ganglion cells in vivo using a newly developed method and reveal the role of inhibitory SC neurons in visual processing by optogenetic manipulation (2). To study the role of inhibitory SC neurons in visually guided behaviours, we will (3) record the activity of optogenetically identified neurons during a visual detection task and investigate how visual and behavioural information is represented on the high-dimensional level in neuronal populations using advanced data analysis. Moreover, to test the causal role on the behaviour we will perturb inhibitory neurons using optogenetic manipulations during the task (4). Finally, we will (5) integrate the experimental data in a computational circuit model of the visual layers of the superior colliculus to investigate how interacting excitatory and inhibitory neurons integrate and shape visual processing. Thus, the overarching goal of this Project is to examine how inhibitory neurons in the superior colliculus sculpt the population activity in during the visual processing and to reveal their causal role in visually guided behaviours.