SPINE MOTILITY AND VISUAL PLASTICITY

描述（改编自申请人的摘要）：树突棘是主要的 在哺乳动物中枢神经系统的突触输入的网站，并已传统上被 被认为是稳定的结构。然而，正如弗朗西斯最初提出的那样， 克里克和最近证实的数据，从我们的小组和其他人， 在分离培养物和脑切片中都有运动。脊柱能动性是 基于动作，似乎是神经元固有的。因为 脊椎在皮质回路中的重要性，脊椎运动可能 可能会对大脑皮层的发育和功能产生重大影响。 在我们以前的工作中，我们发现小鼠皮层的脊柱运动是 在出生后的年龄下调，预示着关键的 单眼剥夺期。虽然小学的关键时期 视觉皮层已经被广泛研究了几十年，它仍然是 不清楚是什么因素终止了它。基于这种相关性，我们假设 关键时期的结束是由于缺乏动力的 刺 我们想结合基因枪GFP 转染、双光子成像、图像解卷积和电子显微镜 在小鼠初级视觉皮层脑切片中，以及在体内， 成像、剥夺和药理学实验。第一个目标将集中在 在表征老鼠V1B中不同皮质层的运动性， 在超微结构水平上重建先前成像的脊柱。 在连续重建中发现相同脊柱成像的能力， 双光子延时电影将使我们能够以前所未有的细节 运动的存在和类型之间是否存在任何相关性， 以及突触前末梢的存在和类型。第二个目标是 确定介导运动的细胞机制，特别强调 在小TGPase的Rho家族的下游靶标上，以及在 研究突触活动在这一过程中的作用。第三个目标 将直接测试脊柱运动是否在关键期起因果作用， 通过检查它是否存在于体内，并通过分析 在单眼剥夺模式中阻止它。 这些研究将阐明结构塑性在 视觉皮层的发展。此外，他们将帮助辨别 单眼剥夺的皮层后果，可能是 弱视和斜视，以及帮助设计治疗策略， 来弥补这些缺陷。更完整地理解 视觉皮层的发育也将改善敏锐度的测量， 对比敏感度和色彩敏感度的言语前儿童和 视力病变的早期诊断。

DESCRIPTION (Adapted from applicant's abstract): Dendritic spines are the major sites of synaptic input in the mammalian CNS and have been traditionally been considered stable structures. Nevertheless, as initially suggested by Francis Crick and confirmed recently by data from our group and by others, spines are motile in both dissociated cultures and in brain slices. Spine motility is action-based and appears to be intrinsic to the neuron. Because of the importance of spines in the cortical circuit, spine motility could have potentially, major consequences in the development and function of the cortex. In our previous work we discovered that spine motility in mouse cortex is down-regulated during the postnatal ages that herald the end of the critical period for monocular deprivation. Although the critical period in primary visual cortex has been studied extensively for many decades, it is still unclear what factors terminate it. Based on this correlation we hypothesized that the end of the critical period is due to the lack of motility of the spines. We want to examine this hypothesis in detail combining gene-gun GFP transfection, two-photon imaging, image deconvolution and electron microscopy of spines in brain slices from mouse primary visual cortex, as well as in vivo imaging, deprivation and pharmacological experiments. The first aim will focus in characterizing the motility in different cortical layers in mouser V1B and in reconstructing at the ultrastructural level the previously imaged spines. The ability of finding in serial reconstructions the same spines imaged in two-photon time-lapse movies will allow us to examine with unprecedented detail whether there are any correlations between the presence and type of motility and the presence and type of presynaptic terminal. The second aim will seek to identify the cellular mechanisms mediating the motility, with special emphasis on the downstream targets of the Rho family of small TGPases and in the examination of the role of synaptic activity in this process. The third aim will directly test if spine motility lays a causal role in the critical period, by examining whether it exists in vivo and by analyzing the consequences of blocking it in the monocular deprivation paradigm. These studies will shed light on the role of structural plasticity in the development of the visual cortex. In addition, they will help discern the cortical consequences of monocular deprivation, effects which may underlie amblyopia and strabismus, as well as help design therapeutic strategies aimed at compensating for these deficits. A more complete understanding of the development of visual cortex will also improve the measurement of acuity, contrast sensitivity and chromatic sensitivity of preverbal children and in early diagnosis of visual pathologies.