Functional organization and plasticity of the visual cortex in mammals

哺乳动物视觉皮层的功能组织和可塑性

• 批准号: RGPIN-2014-06503
• 负责人: Casanova, Christian
• 金额: $ 2.48万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567850
• 关键词: Functional; organization; plasticity; visual; cortex

Brain plasticity is necessary not only for learning and memory but also to allow the brain to rapidly adapt to changes in the environment or to injuries. Complex behavior of mammals relies on the cooperation between multiple brain areas, particularly at the cortical level where neuronal networks are engaged or disengaged in reaction to external or endogenous stimuli. In the visual system, the cortical analysis occurs first at the level of the primary visual cortex and continues in higher-order areas through serial and parallel streams. All visual areas contain a representation (partial or complete) of the visual world and are organized in a topographic way (visuotopic maps). Further, in some species, a functional sub-organization can be observed in cortical areas (e.g. modules of ocular dominance, orientation). It is through the concerted activity of these distributed networks that an animal is able to interpret a visual scene, integrate its information with other sensory modalities, all in order to adopt the proper visuomotor behaviour. The overall goal of this research program aims to determine how brain networks can be modulated by sensory experience and how they can adapt to insults. As a first step, my lab will focus on the comparative study of the structure-function of the visual cortex in species (mice, rabbits and tree shrews) with specific cortical characteristics (functional maps organized in modules vs. a salt and pepper organization). We will determine how the environment changes the visual brain’s connectivity and functioning and if it can promote recovery from lesions by reinstating plasticity. Environmental enrichment (EE) is a powerful implement to modulate and enhance plasticity. We hypothesize that enrichment will induce a large-scale functional refinement of visuotopic maps and cortical modules as well as an increase in the coupling (cross-correlation) between the different areas of the cortical visual network. We also hypothesize that EE will facilitate network reorganization following an insult to one of its component. We will take advantage of mapping techniques developed recently in the laboratory. Optical brain imaging (intrinsic and voltage-sensitive dyes) will be used to visualize the activity of the visual areas as well as the functional connectivity between them in resting and stimulus- induced states before and after the enrichment of their environment. A range of visual stimuli varying in their complexity will be used to highlight specific sensitivity to stimulus types within the visual cortical network. These experiments will be made in conjunction with electrophysiological recordings and complemented by fMRI studies. Experiments will be performed using animals placed in an enriched milieu either in adulthood or during their development. The proposed program will contribute to our understanding of the impact of environment on brain connectivity and function and increase our knowledge on neuronal plasticity. The combination of brain imaging, optogenetic, and electrophysiology to study the development, structure and function of the neocortex in a phylogenetic context will provide an innovative multidisciplinary training environment.

大脑的可塑性不仅是学习和记忆所必需的，也是让大脑迅速适应环境变化或损伤所必需的。哺乳动物的复杂行为依赖于多个脑区之间的合作，特别是在大脑皮层水平上，神经元网络参与或脱离对外部或内源性刺激的反应。在视觉系统中，皮质分析首先发生在初级视觉皮质水平，并通过串行流和并行流在较高级别的区域继续进行。所有视觉区域都包含视觉世界的表示(部分或全部)，并以地形图的方式组织(视觉地图)。此外，在一些物种中，可以在皮质区域观察到功能性亚组织(例如，眼优势模块、定向)。正是通过这些分布式网络的协同活动，动物才能够解释视觉场景，将其信息与其他感官方式相结合，所有这些都是为了采用适当的视觉运动行为。这项研究计划的总体目标是确定大脑网络如何受到感官体验的调节，以及它们如何适应侮辱。作为第一步，我的实验室将专注于对具有特定皮质特征(按模块组织的功能图与盐和胡椒组织的功能图)的物种(老鼠、兔子和树鼠)的视觉皮质结构-功能的比较研究。我们将确定环境如何改变视觉大脑的连通性和功能，以及它是否可以通过恢复可塑性来促进损伤的恢复。环境富集化是调节和提高塑性的有力工具。我们假设，丰富将导致视觉地图和皮质模块的大规模功能细化，以及皮质视觉网络不同区域之间的耦合(互相关联)增加。我们还假设，在其组件之一受到侮辱后，EE将促进网络重组。我们将利用实验室最近开发的测绘技术。光学脑成像(固有的和电压敏感的染料)将被用来可视化视觉区域的活动以及它们之间在休息和刺激诱导状态下在环境丰富之前和之后的功能连接。一系列复杂程度不同的视觉刺激将被用来突出视觉皮层网络中对刺激类型的特定敏感性。这些实验将与电生理记录一起进行，并得到功能磁共振研究的补充。实验将使用被放置在丰富环境中的动物进行，无论是在成年还是在它们的发育过程中。该计划将有助于我们了解环境对大脑连通性和功能的影响，并增加我们对神经元可塑性的了解。脑成像、光遗传学和电生理学相结合，在系统发育的背景下研究新皮质的发育、结构和功能，将提供一个创新的多学科训练环境。