Molecular genetics on the hippocampus & neocortex in long term declarative memory

海马体的分子遗传学

• 批准号: 6652858
• 负责人: SUSUMU TONEGAWA
• 金额: $ 16.54万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6652858
• 关键词: NMDA receptors; calcineurin; gene targeting; genetically modified animals; hippocampus; laboratory mouse; learning; long term potentiation; memory; molecular genetics; neocortex; neural information processing; neural plasticity; pyramidal cells; synapses

GRANT=P50MH58880-01A1-0002 DESCRIPTION: (Adapted from the Application) This project contributes to the Center's overall objectives by examining the roles of the NMDA receptor and calcineurin (PP2B) functions in hippocampal CA1 pyramidal cells in hippocampus-dependent learning. How synaptic plasticity in the hippocampus contributes to hippocampus-dependent learning is one of the major goals of the Center. Activation of NMDA receptors in CA1 neurons is known to play a pivotal role in the induction of several forms of synaptic plasticity such as LTP and LTD at CA1 synapses. On the other hand, calcineurin is known to play a critical role in the induction of LTD. Our previous studies on CA1-specific NR1 KO (CA1 KO NR1) mice which were conducted collaboratively between our and Wilson's laboratories showed that NMDA- dependent synaptic plasticity at CA1 synapses plays a crucial role in spatial learning. These studies also suggested that the spatial learning impairment exhibited by the NR1 KO mice is probably due to the animal's inability to generate normal place fields in the CAI area which may be required for place-specific, coordinated firing of neurons in downstream brain areas. We will further test this hypothesis by recording the activities of neuron ensembles in the subiculum and the deep layers of the entorhinal cortex of CA1 KO NR1 mice. While NMDA receptor-mediated synaptic plasticity seems to play a crucial role in spatial learning, the relative contributions of LTP and LTD in this cognitive process remain unknown. We predict that a loss of calcineurin will result in a selective loss of LTD with preservation of LTP. We therefore plan to construct CA1-specific PP2B knockout mice (called CA 1 KO Crib 1) by the method already available in Tonegawa's laboratory. These mice will be analyzed by subjecting them to electrophysiological and behavioral studies. In addition to the procedures already utilized in our laboratories during the analysis of the CA1-specific N-R1 KO mice, expertise in Bear's laboratory on LTD will also be applied (Specific Aim #3). Another set of experiments revisits the unsettled issue of whether the hippocampus plays a crucial role not only in spatial learning but also in non-spatial learning. We will address this issue by subjecting the CAIKNR1 mice to a non-spatial learning paradigm, social transmission of food preference (Specific Aim #2). Individual Project #2 also contributes to the Center's overall objectives by examining the role of cAMP-dependent transcriptional factor CREB in the hippocampal CA1 area as well as in the neocortex in memory consolidation and maintenance (Specific Aim #4). Earlier studies by others with Drosophila and Aplysia implicated CREB-dependent protein synthesis in long term memory or long term facilitation. Although an effort was made by others to extend this notion to mammals using unrestricted CREB KO mice, the lack of regional and temporal restriction in the gene knockout and the incomplete inactivation of CREB activity prevented a firm conclusion. In addition, no information could be obtained as to where, for instance in hippocampus or parietal cortex, CREB is required in the consolidation and maintenance of hippocampus-dependent long term memory. We plan to address this central issue in memory research by creating and analyzing a new set of CREB KO mice in which gene knockout is complete and is restricted to the CA1 area or to the parietal and temporal cortices (see Core #1 for the construction of the latter mice). We also propose to produce and analyze CREB KO mice in which the gene knockout can be induced in a specific area of the brain after maturation in order to study adult function of CREB independent of its developmental function. Another CREB mouse to be made using a dominant negative form of CREB (dn CREB) will allow spatially-restricted inducible inhibition of endogenous CREB function. The inducible knockout or inhibition system will enable us to study the roles of a specific gene product (in this case CREB) in different phases of themnemonic process such as acquisition vs. consolidation (or maintenance) of memory. With all of these CREB gene manipulated mice, our or Bear's laboratory will analyze LTP and LTD (or depotentiation), particularly late LTP (L-LTP) at CA1 synapses of the hippocampus or at Te-2 synapses of the neocortex. Both our laboratory and Wilson's will subject the same mice to spatial learning and memory paradigms to assess possible impairments in the learning and/or memory phases of the behavior. In a closely related study as part of Individual Project #6, Bear's laboratory will extend the behavioral analysis to include visual recognition memory. All these studies may permit correlations of physiological and behavioral defects and also may identify brain site(s) and phases(s) of the mnemonic process in which CREB plays a crucial role. Finally, Wilson's laboratory will analyze some of these CREB mice by large-scale recordings in order to correlate defects in synaptic plasticity and behaviors to defects in the activity of neuronal ensembles.

授权= P50 MH 58880 - 01 A1 -0002 描述：（改编自应用程序）该项目有助于 通过检查NMDA的作用， 受体和钙调磷酸酶（PP 2B）的功能 依赖于校园的学习。突触可塑性是如何 海马体有助于海马体依赖性学习， 中心的主要目标。海马CA 1区神经元NMDA受体的激活 已知在诱导多种形式的突触中发挥关键作用 可塑性，如LTP和LTD在CA 1突触。 另一方面，在一项研究中， 已知钙调神经磷酸酶在LTD的诱导中起关键作用。 对CA 1特异性NR 1 KO（CA 1 KO NR 1）小鼠进行的研究 我们和威尔逊实验室的合作表明，NMDA- 在CA 1突触的依赖性突触可塑性在空间上起着至关重要的作用， 学习这些研究还表明，空间学习障碍， NR 1基因敲除小鼠表现出的免疫缺陷可能是由于动物不能 在CAI区域中生成正常位置字段， 下游脑区神经元的位置特异性协调放电。我们 我将通过记录神经元集合的活动来进一步验证这一假设 在海马下托和内嗅皮层深层， 小鼠虽然NMDA受体介导的突触可塑性似乎起着关键作用， 在空间学习中的作用，LTP和LTD在这方面的相对贡献 认知过程仍然未知。我们预测钙调神经磷酸酶的缺失 将导致在保留LTP的情况下选择性地损失LTD。因此我们 计划构建CA 1特异性PP 2B敲除小鼠（称为CA 1 KO Crib 1)用利根川实验室已有的方法。这些老鼠会 通过对它们进行电生理和行为研究来分析。 除了在我们的实验室中已经使用的程序外， CA 1特异性N-R1 KO小鼠的分析，Bear实验室的专业知识， 还将应用LTD（具体目标#3）。另一组实验重新审视了海马体是否不仅在空间学习中， 非空间学习我们将通过使CAIKNR 1小鼠 非空间学习范式，食物偏好的社会传递 （具体目标#2）。个别项目#2也有助于中心的总体目标， 检查海马CA 1区以及新皮质中cAMP依赖性转录因子CREB在记忆巩固和维持中的作用（具体目标#4）。其他人对果蝇和果蝇的早期研究表明，CREB依赖的蛋白质合成与长期记忆或长期易化有关。尽管其他人做出了努力， 使用不受限制的CREB KO小鼠将这一概念扩展到哺乳动物，基因敲除中缺乏区域和时间限制以及CREB活性的不完全失活阻止了确定的结论。此外，没有信息可以获得，例如在海马或顶叶皮层，CREB是巩固和维持海马依赖性长期记忆所必需的。我们计划通过创造和分析一组新的CREB基因敲除小鼠来解决记忆研究中的这个中心问题。 该基因敲除是完全的，并限于CA 1区或顶叶和颞叶皮质（参见核心#1以构建后一种小鼠）。我们还建议生产和分析CREB KO小鼠，其中基因敲除可以在成熟后在大脑的特定区域中诱导，以研究CREB独立于其发育功能的成年功能。使用显性阴性形式的CREB（dn CREB）制备的另一种CREB小鼠将允许内源性CREB功能的空间限制性诱导抑制。 诱导型敲除或抑制系统将使我们能够研究特定基因产物（在这种情况下CREB）在记忆过程的不同阶段（如记忆的获得与巩固（或维持））中的作用。对于所有这些CREB基因操纵的小鼠，我们或Bear的实验室将分析LTP和LTD（或去增强），特别是海马CA 1突触或新皮质Te-2突触的晚期LTP（L-LTP）。我们的实验室和威尔逊的实验室都将对相同的小鼠进行空间学习和记忆范式，以评估行为的学习和/或记忆阶段可能的损伤。在一个密切相关的 作为个人项目#6的一部分，贝尔的实验室将扩展行为分析，包括视觉识别记忆。所有这些研究可能允许生理和行为缺陷的相关性，也可能确定CREB发挥关键作用的记忆过程的大脑部位和阶段。最后，威尔逊的实验室将通过大规模记录来分析其中一些CREB小鼠，以便将突触可塑性和行为的缺陷与神经元集合活动的缺陷联系起来。