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

GRANT=P50MH58880-01A1-0002 描述：(改编自应用程序)本项目贡献 通过审查NMDA的作用来实现中心的总体目标 受体和钙调神经磷酸酶(PP2B)在海马CA1区锥体中的作用 海马体依赖学习中的细胞。突触的可塑性如何在 海马体有助于海马体依赖学习是 中心的主要目标。CA1神经元NMDA受体的激活 已知在几种形式的突触的诱导中起着关键作用 CA1突触的可塑性，如LTP和LTD。另一方面， 已知钙调神经磷酸酶在LTD的诱导中起关键作用。我们以前的 CA1特异性NR1KO(CA1KO NR1)小鼠的研究 我们和威尔逊的实验室之间的合作表明，NMDA- CA1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 NR1KO小鼠表现出的能力可能是由于该动物无法 在CAI区域中生成正常的位置字段，这可能需要 大脑下游区域特定位置、协调的神经元放电。我们 将通过记录神经元集合的活动来进一步检验这一假说 在CA1 KO NR1内嗅皮质的下丘脑和深层 老鼠。而NMDA受体介导的突触可塑性似乎起着至关重要的作用 LTP和LTD在空间学习中的相对贡献 认知过程尚不清楚。我们预测钙调神经磷酸酶的丢失 将导致在保留LTP的情况下选择性地失去LTD。因此，我们 计划构建CA1特异性PP2B基因敲除小鼠(称为CA1 KO婴儿床 1)采用Tonegawa实验室中已有的方法。这些老鼠会 通过对他们进行电生理和行为研究进行分析。 除了我们实验室已经在使用的程序之外， 分析CA1特异性N-R1KO小鼠，贝尔斯登实验室对 LTD也将适用(具体目标3)。另一组实验重温了尚未解决的问题，即海马体是否不仅在空间学习中发挥关键作用，而且在 非空间学习。我们将通过让CAIKNR1小鼠研究这个问题来解决这个问题 以非空间学习范式、社会传递食物偏好 (具体目标2)。个人项目#2也通过以下方式为中心的总体目标做出贡献 研究cAMP依赖转录因子CREB在海马CA1区以及新皮质中在记忆巩固和维持中的作用(特定目标#4)。其他人对果蝇和海兔的早期研究表明，CREB依赖的蛋白质合成与长期记忆或长期促进有关。尽管其他人也做出了努力 将这一概念推广到使用不受限制的CREB KO小鼠的哺乳动物，基因敲除缺乏区域和时间限制以及CREB活性的不完全失活阻碍了确定的结论。此外，无法获得关于CREB在巩固和维持依赖于海马体的长期记忆中在哪里需要的信息，例如在海马区或顶叶皮质。我们计划通过创建和分析一组新的CREB KO小鼠来解决记忆研究中的这个中心问题 哪个基因敲除是完全的，并且仅限于CA1区或顶叶和颞叶皮质(后一种小鼠的结构见核心#1)。我们还建议建立和分析CREB KO小鼠，在成熟后可以在大脑的特定区域诱导基因敲除，以研究CREB独立于其发育功能的成人功能。另一种使用显性CREB阴性形式的CREB(DN CREB)的CREB小鼠将允许对内源性CREB功能的空间受限诱导抑制。 可诱导的基因敲除或抑制系统将使我们能够研究特定基因产物(在这种情况下是CREB)在记忆过程的不同阶段的作用，如记忆获得与巩固(或维持)。利用所有这些CREB基因操作的小鼠，我们或贝尔的实验室将分析LTP和LTD(或去增强)，特别是在海马区CA1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例，以评估行为的学习和/或记忆阶段可能存在的损害。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，将视觉识别记忆包括在内。所有这些研究可能允许生理和行为缺陷之间的关联，也可能识别记忆过程的脑部位(S)和阶段(S)，CREB在其中发挥关键作用。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缺陷与神经元整体活动缺陷联系起来。

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.