Experience-Dependent Enhancement of Neuronal Integration

神经元整合的经验依赖性增强

• 批准号: 7221894
• 负责人: ARTHUR CZUPRYN
• 金额: $ 5.01万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-09 至 2008-09-08
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7221894
• 关键词: Poland; apoptosis; cell differentiation; confocal scanning microscopy; fluorescence microscopy; immunocytochemistry; international cooperation; laboratory mouse; nerve stem cell; nervous system transplantation; neural degeneration; neural plasticity; neurogenesis; neurophysiology; photoactivation; postdoctoral investigator; sensory deprivation; somesthetic sensory cortex; stem cell transplantation; stimulus /response

DESCRIPTION (provided by applicant): The objective of the proposed experiments is to increase the repair efficiency of damaged or degenerated neuronal circuits in the brain, focusing the interest on restoration of corticocortical or cortico-thalamic neurons of adult mice in vivo. Immature neurons and neural precursors will be transplanted in the cortex undergoing a defined and controllable targeted degeneration of selective neurons (neurodegeneration). This apoptotic neuronal degeneration will be biophysically induced by photoactivation of targeting molecules, causing specific degeneration only to desired subpopulations of neurons in vivo. In this project, survival and differentiation of new neurons will be modulated by sensory experience, which produces activity-dependent plastic changes in the somatosensory cortex of adult mice. The group of Prof. Macklis has shown that neurons can be replaced by immature neuroblasts transplanted into the cerebral cortex after targeted degeneration of selected neurons. These newly incorporated cells can differentiate appropriately into precisely the right kind of neuron, re-establish appropriate long-distance projections, develop a mature phenotype, and make appropriate connections with recipient circuitry. The Macklis lab also showed, for the first time, that neurogenesis can be induced in the adult mouse neocortex, and new neurons can thereby be recruited from endogenous precursors manipulated in situ, without transplantation. It is postulated that targeted neuronal cell death produces local reexpression of developmental signals responsible for directed neuronal migration, differentiation, and connectivity of transplanted neuroblasts, or either transplanted or endogenous precursors. Complementary to these results, there is growing evidence in the literature suggesting that endogenous proliferation and differentiation of neurons (neurogenesis), which in the intact adult mouse brain is observed to the hippocampus and olfactory bulb, can be regulated by experience. In the proposed research project, it will be evaluated whether the effectiveness of differentiation, integration, and survival within circuitry by transplanted neuroblasts in the somatosensory cortex of mice can be improved by experimental manipulations of their circuit activity. The proposed research will evaluate the effects of induction of activity-dependent plastic changes in the adult somatosensory cortex, achieved by sensory stimulation and sensory deprivation. Intense long-lasting sensory stimulation will be induced by housing animals in completely new "tactile-rich" area (enriched environment) or by intense forced movement of tactile whiskers (mechanical stimulation of vibrissae). Sensory deprivation will base on long-lasting tactile whisker trimming or vibrissectomy (restriction of sensory input to the cortex). The effects on survival, differentiation, and integration of transplanted neuroblasts in the adult cortex undergoing experimentally-induced neurodegeneration and a range of stimulation-dependent activation will be studied with a range of established immunocytochemical, neuroanatomical, and genetic tracer methods well established in the Macklis lab, analyzed using fluorescence and confocal microscopy to evaluate cellular integration, synaptic circuit formation, and trans-synaptic functional activation.

描述（由申请人提供）： 所提出的实验的目的是增加大脑中受损或退化的神经元回路的修复效率，将兴趣集中在成年小鼠体内皮质或皮质-丘脑神经元的恢复上。未成熟的神经元和神经前体将被移植到皮质中，经历选择性神经元的确定的和可控的靶向变性（神经变性）。这种凋亡性神经元变性将通过靶向分子的光活化而生物药理学地诱导，从而在体内仅对所需的神经元亚群引起特异性变性。在这个项目中，新神经元的存活和分化将受到感觉经验的调节，这会在成年小鼠的躯体感觉皮层中产生活动依赖性的可塑性变化。Macklis教授的研究小组已经表明，在选定的神经元发生靶向变性后，神经元可以被移植到大脑皮层中的未成熟神经母细胞所取代。这些新整合的细胞可以适当地分化成正确的神经元，重新建立适当的长距离投射，发育成熟的表型，并与受体电路建立适当的连接。Macklis实验室还首次表明，神经发生可以在成年小鼠新皮层中诱导，从而可以从原位操作的内源性前体中招募新的神经元，而无需移植。据推测，靶向神经元细胞死亡会产生负责定向神经元迁移的发育信号的局部重新表达， 分化和连接，或者移植的或内源性前体。补充这些结果，有越来越多的证据表明，在完整的成年小鼠大脑中观察到的海马和嗅球的神经元的内源性增殖和分化（神经发生），可以通过经验进行调节。在拟议的研究项目中，将评估是否可以通过实验操作其回路活动来改善小鼠躯体感觉皮层中移植的神经母细胞在回路内的分化、整合和存活的有效性。这项拟议的研究将评估通过感觉刺激和感觉剥夺诱导成人体感皮层活动依赖性可塑性变化的影响。通过将动物圈养在全新的“触须丰富”区域（丰富的环境）或通过触觉须的强烈强制运动（触须的机械刺激），将诱导强烈持久的感觉刺激。感觉剥夺将基于长期的触觉胡须修剪或触须切除术（限制对皮层的感觉输入）。将使用Macklis实验室中已建立的一系列免疫细胞化学、神经解剖学和遗传示踪剂方法研究对经历实验诱导的神经变性和一系列刺激依赖性激活的成年皮质中移植的成神经细胞的存活、分化和整合的影响，使用荧光和共聚焦显微镜分析以评估细胞整合、突触回路形成，和跨突触功能激活。