The Development of Direction Selectivity in Visual Cortex

描述（由申请人提供）：对运动物体的感知和对眼球运动的视觉引导都需要皮层回路对视觉场景中运动物体产生准确的神经表征。这一过程严重依赖于皮质神经元选择性地对移动刺激的方向作出反应。本研究的目的是继续探讨视觉经验在雪貂初级视觉皮层方向选择反应发展中的作用。之前的研究表明，经验在方向选择性皮层反应的早期成熟中起着独特而重要的作用。如果在睁眼后的两周内没有视觉体验，方向选择反应就不会出现，并且不会在随后的视觉体验中恢复。拟议的实验将这条探究线扩展到解决四个问题。(1)运动视觉刺激的经验是否为方向选择性皮层反应的构建提供了指导性线索？(2)先天神经元调谐特性在方向选择反应的经验依赖性出现中起什么作用？(3)皮层第4层回路和皮层第2/3层回路的变化对方向选择反应的经验依赖性产生有何贡献？(4)方向选择性反应的出现是否伴随着解剖连接排列的方向特异性改变？这些实验采用了最先进的功能成像技术，以一种新颖的实验范式，使我们能够监测视觉体验对体内皮层回路发育的影响。这些实验将有助于更好地理解在发育障碍中常见的运动感知缺陷，更广泛地说，它们将为经验塑造皮层回路发育的机制提供新的见解。

DESCRIPTION (provided by applicant): Both the perception of moving objects and the visual guidance of eye movements require that cortical circuits generate an accurate neural representation of moving objects in the visual scene. This process is critically dependent on cortical neurons that respond selectively to the direction of moving stimuli. The goal of the proposed research is to continue our inquiry into the role of visual experience in the development of direction selective responses in ferret primary visual cortex. Work during the previous period of support demonstrated that experience plays a unique and essential role in the early maturation of direction selective cortical responses. If visual experience is withheld for the 2 weeks following eye opening, direction selective responses fail to emerge, and are not recovered by subsequent visual experience. The proposed experiments extend this line of inquiry to address four questions. (1) Does experience with moving visual stimuli serve as an instructive cue for the construction of direction selective cortical responses? (2) What role do innate neuronal tuning properties play in the experience dependent emergence of direction selective responses? (3) What contribution do changes in cortical layer 4 circuits and cortical layer 2/3 circuits make to the experience dependent emergence of direction selective responses? (4) Is the emergence of direction selective responses accompanied by direction-specific alterations in the arrangement of anatomical connections? These experiments employ state of the art functional imaging techniques in a novel experimental paradigm that permits us to monitor the impact of visual experience on developing cortical circuits in vivo. These experiments will contribute to a better understanding of deficits in motion perception that are common in developmental disorders, and more broadly, they will provide new insights into the mechanisms by which experience shapes cortical circuit development.