CRCNS: Neural signals that maintain/refresh LTP and memory

实验表明，干扰LTP后的CaMKI I可以消除LTP，这是一个强烈的迹象 CaMKll在LTP维护过程中的重要性。CaMKll全酶由12个催化亚基组成。 在开启状态下，每个亚基都被磷酸化，因此是活性的。当一个站点成为 去磷酸化后，它可以被邻近的活性亚基刷新(重新磷酸化)。 目标1.更新是否依赖于活动？CaMKll刷新过程需要低水平的钙，但 这一水平的实现是否依赖于自发的神经活动尚不清楚。因此，a 人们感兴趣的基本问题是，LTP或记忆的维持是否需要神经活动。在……里面 目标1A，我们将在急性海马片上测试这一点。在目标1B中，我们将探讨活动是否必要 用果蝇在行为水平上保持记忆。虽然我们知道CaMKll是 对果蝇记忆重要的是，实验还没有测试CaMKll在记忆中是否重要 维修。鉴于这一问题对于解释活动对记忆的影响的重要性，我们将 进行关键擦除测试，以确定CaMKll是否调节果蝇的记忆存储。 目的2.体内是否存在CaMKll亚单位交换：分子刷新的潜在机制？ 根据理论模型，开关的稳定性可能长于任何亚基的寿命，如果CaMKll 通过亚基交换进行蛋白质周转：新插入的非磷酸化亚基可能是 被邻近的磷酸化亚基磷酸化，从而提供分子刷新。我们会 首次尝试测试活细胞(果蝇和海马体)中是否发生亚单位交换 并对其活动依赖性进行了表征。 目标3.计算模型：需要什么样的神经活动来更新CaMKll 磷酸化？静息Ca~(2+)水平和自发动作电位或mEPSP的水平 估计，以及这些反应的速度。我们将使用经过验证的CaMKll计算模型来 确定这些短暂的Ca~(2+)事件是否足以刷新CaMKll和 从而保证了存储信息的稳定性。结果将对根本问题产生重要影响。 刷新反应是由自发活动介导的，还是取决于 重放记忆的网络进程。 相关性(请参阅说明)： 了解在突触存储记忆的过程将对几个健康问题产生重大影响 有问题。特别是，成瘾已被证明与CaMKll的持续变化有关 基底节网络中的突触对成瘾行为至关重要。拟议的工作可能 提供关闭CaMKll的方法，从而减少成瘾行为。CaMKll也一直表现强劲 与记忆障碍和中风有关。

Experiments show that interference with CaMKI I after LTP can erase LTP, a strong indication of the importance of CaMKll in the LTP maintenance process. CaMKll holoenzymes contain 12 catalytic subunits. In the ON state, each subunit is phosphorylated and therefore active. When a site becomes dephosphorylated, it can be refreshed (rephosphorylated) by a neighboring active subunit. Aim 1. Is refresh dependent on activity? The CaMKll refresh process requires low levels of Ca, but whether achievement of this level is dependent on spontaneous neural activity is not known. Therefore, a fundamental question of interest is whether the maintenance of LTP or memory requires neural activity. In Aim 1A, we will test this in acute hippocampal slices. In Aim 1B, we will explore whether activity is necessary for maintaining memory at the behavioral level using Drosophila. Although it is known that CaMKll is important for Drosophila memory, experiments have not yet tested whether CaMKll is important in memory maintenance. Given the importance of this issue for interpreting the effects of activity on memory, we will conduct the critical erasure test for determining whether CaMKll mediates memory storage in Drosophila. Aim 2. Does CaMKll subunit exchange occur in vivo: a potential mechanism for molecular refresh? According to theoretical models, switch stability could long outlive the lifetime of any subunit if CaMKll underwent protein turnover by subunit exchange: a newly inserted unphosphorylated subunit could be phosphorylated by a neighboring phosphorylated subunit, thereby providing a molecular refresh. We will make the first attempts to test whether subunit exchange occurs in living cells (Drosophila and hippocampus) and characterize its activity-dependence. Aim 3. Computational modelling: what kinds of neural activity are required to refresh CaMKll phosphorylation? The level of resting Ca2+, and that during spontaneous action potentials or mEPSPs can be estimate, as well as the rate of these reactions. We will use a verified computational model of CaMKll to determine whether these brief Ca2+ events are sufficient to refresh the phosphorylated state of CaMKll and thus ensure the stability of stored information. The results will bear importantly on the fundamental question of whether refresh reactions are mediated by spontaneous activity, or alternatively, are dependent on a network process that replays memories. RELEVANCE (See instructions): Understanding the processes that store memory at synapses will have major implications for several health problems. In particular, addiction has been demonstrated to involve persistent changes in CaMKll at synapses in the basal ganglia networks that are critical for addictive behaviors. The proposed work may provide ways to turn off CaMKll and thus reduce addictive behaviors. CaMKll has also been strongly implicated in memory disorders and stroke.