NEURONAL PATHWAYS UNDERLYING IN VITRO MOTOR LEARNING

体外运动学习的神经通路

• 批准号: 8247748
• 负责人: JOYCE KEIFER
• 金额: $ 31.42万
• 依托单位: UNIVERSITY OF SOUTH DAKOTA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8247748
• 关键词: Acoustic Nerve; Address; Adenylate Cyclase; Affect; Alzheimer' s Disease; Animals; Area; Biological Models; Blinking; Brain Stem; Brain-Derived Neurotrophic Factor; CREB1 gene; Calcium; Characteristics; Conditioned Stimulus; Cornea; Cyclic AMP-Dependent Protein Kinases; Detection; Disease; Effectiveness; Electric Stimulation; Elements; Ephrins; Event; Funding; Gene Targeting; Genes; Growth; Human; Impaired cognition; In Vitro; Investigation; Label; Laboratories; Lead; Learning; Link; Mediating; Memory; Metalloproteases; Mitogen-Activated Protein Kinases; Modeling; Modification; Molecular; Motor Neurons; Neurons; Pathway interactions; Phosphotransferases; Preparation; Presynaptic Terminals; Process; Protein Kinase; RNA Interference; Research; Role; Signal Pathway; Signal Transduction; Site; Source; Specificity; Staging; Stimulus; Study models; Synapses; System; Testing; Trigeminal nerve structure; Turtles; Vertebrates; Work; abducens nerve; analog; base; blink reflexes; calmodulin-dependent protein kinase II; classical conditioning; conditioning; immunocytochemistry; in vitro Model; motor learning; neuromechanism; normal aging; paired stimuli; postsynaptic; presynaptic; public health relevance; relating to nervous system; response; trafficking; voltage

DESCRIPTION (provided by applicant): The classically conditioned eyeblink response is a well-studied model for understanding the neural mechanisms underlying associative learning. Classical conditioning is an example of associative learning that occurs when a reinforcing unconditioned stimulus (US) is contingent on the occurrence of a preceding conditioned stimulus (CS). In humans and other vertebrates, an eyeblink reflex in response to a tone can be learned when the tone is repeatedly paired with an airpuff to the cornea. We have developed an in vitro model of vertebrate associative learning using a turtle brain stem preparation that generates a neural analog of eyeblink classical conditioning to examine cellular mechanisms of conditioned response (CR) acquisition. In place of using tone and airpuff stimuli as in behaving animals we use paired stimulation of the auditory nerve (the "tone" CS) with the trigeminal nerve (the "airpuff" US) that results in burst discharge in the abducens nerve, which controls blinking in this species, characteristic of conditioned eyeblink responses. Our studies in the last funding period have focused on detailing molecular events that take place during in vitro conditioning related to protein kinase activation and AMPAR trafficking. These have allowed us to construct a two-stage model for conditioning in which synaptic delivery of GluR1-containing AMPARs initially activate silent synapses, followed by synaptic incorporation GluR4 subunits that support the acquisition of CRs. The third renewal of our project will further investigate the molecular mechanisms that underlie associative learning in vertebrates using this in vitro model of eyeblink classical conditioning. The following Specific Aims will be examined: 1) Specific elements of our model for conditioning will be tested directly using selective knockdown of gene targets by the RNAi approach. 2) To investigate the signal transduction mechanisms for coincidence detection and initiation of acquisition. 3) Our previous studies indicated that synaptic delivery of GluR1 was PKA-dependent while GluR4 was PKC- dependent. However, both require ERK. In this Aim, we will examine whether intracellular compartmentalization maintains the functional specificity of these kinases. 4) We have shown that brain-derived neurotrophic factor (BDNF) is required for synaptic AMPAR incorporation and conditioning, and morphological alterations of presynaptic terminals. Here, we will assess whether the coordinate pre- and postsynaptic modifications that occur during conditioning are mediated by the trans-synaptic eph/ephrin signaling system working in combination with BDNF/TrkB. Detailed investigation of the mechanisms that underlie learning and memory are fundamental to understanding disease states affecting these processes and will contribute to an overall effort to understand and treat the cognitive decline associated with normal aging and Alzheimer's disease. PUBLIC HEALTH RELEVANCE: Using our in vitro model system of eyeblink classical conditioning, we have been able to directly link the function of metalloproteinases, brain-derived neurotrophic factor (BDNF) expression, synaptic AMPAR delivery, and associative learning. The studies performed in this proposal will contribute to a greater understanding of the molecular events that lead to associative learning and provide a potentially fruitful basis for future research into molecular mechanisms that underlie the cognitive decline associated with normal aging and Alzheimer's disease.

描述（由申请人提供）：经典条件的Eykeblink响应是一个认真的模型，用于了解关联学习的神经机制。经典条件是当加强无条件的刺激（US）取决于前面条件刺激（CS）的情况下，这是相关学习的一个例子。在人类和其他脊椎动物中，当音调与Airpuff搭配到角膜时，可以学习一种响亮的反射。我们已经使用乌龟脑干制剂开发了一种脊椎动物缔合学习的体外模型，该模型产生了Eyeblink经典调节的神经类似物，以检查条件反应（CR）的细胞机制。代替使用语调和Airpuff刺激，就像在行为动物中一样，我们使用了对听觉神经的配对刺激（“音调” C）与三叉神经（“ Airpuff” US）的配对刺激，从而导致外皮神经的破裂，该神经控制在该物种中闪烁的闪烁，有条件的眼线链接反应。我们在最后一个资金期间的研究重点是详细介绍与蛋白激酶激活和AMPAR运输有关的体外调节过程中发生的分子事件。这些使我们能够构建一个两阶段的模型，用于调节，其中含GlUR1的AMPAR的突触传递最初激活无声突触，然后是支持CRS获得的突触掺入GLUR4亚基。我们项目的第三个续约将进一步研究使用这种眼闪链经典条件的体外模型在脊椎动物中进行关联学习的分子机制。将检查以下具体目标：1）我们的调节模型的特定元素将使用RNAi方法选择性敲低基因靶标直接测试。 2）调查了巧合检测和启动采集的信号转导机制。 3）我们先前的研究表明，GlUR1的突触递送是PKA依赖性的，而GLUR4依赖于PKC。但是，都需要ERK。在此目标中，我们将检查细胞内分室化是否保持这些激酶的功能特异性。 4）我们已经表明，突触AMPAR掺入和调节和突触前末端的形态学改变是必需的脑源性神经营养因子（BDNF）。在这里，我们将评估调节过程中发生的坐标前和突触后修饰是否由跨突触EPH/Ephrin信号系统与BDNF/TRKB联合起作用。详细研究了学习和记忆基础的机制是理解影响这些过程的疾病状态的基础，并将有助于理解和治疗与正常衰老和阿尔茨海默氏病有关的认知下降。 公共卫生相关性：使用我们的Eykblink经典条件的体外模型系统，我们能够直接连接金属蛋白酶，脑源性神经营养因子（BDNF）表达，突触AMPAR的交付和关联学习的功能。在该提案中进行的研究将有助于更了解导致联想学习的分子事件，并为未来对分子机制的研究提供了潜在富有成效的基础，这些研究是与正常衰老和阿尔茨海默氏病有关的认知下降。