Mechanisms in the Expression and Decay of Long-Term Habituation Memory

描述（由申请人提供）：学习产生行为、生理和基因表达的长期变化。尽管这一原理在动物王国中得到了充分的证明，但学习和记忆的基本方面仍不清楚：1)支持长期记忆的生理和遗传变化是如何通过神经回路整合的。2)遗忘是否代表长期记忆过程的衰退或主动擦除过程；3)记忆获得和保持的个体差异是如何产生的。为了解决学习和记忆中的这些基本问题，我们提出了一套简单的实验，使用长时间的适应性训练来训练海兔尾巴引发的虹吸-退缩反射（T-SWR）。一组动物将接受长期的习惯训练（5组，每组30次刺激，每次刺激30秒，每次刺激间隔90分钟）。这种训练产生了T-SWR行为的持久和单方面的减少。为了确定LTH的生理相关性，经过训练的动物将被麻醉并减少到虹吸管+尾巴准备，以便在正在进行的行为中从T-SWR回路中进行生理记录。通过比较每只动物受过训练和未受过训练的尾巴诱发的神经活动，将有可能确定LTH训练引发的长期神经可塑性部位。生理记录后，T-SWR回路每层训练侧和未训练侧的神经元将被物理隔离。为了确定LTH的分子相关性，将从收获的细胞中提取RNA，进行反向转录，并使用微阵列进行分析。通过对训练后1天和7天收获的动物重复相同的程序，将有可能确定记忆表达（1天）和衰退（7天）的生理和遗传相关性。此外，组内分析将能够识别生理和转录因素，预测长期习惯的获得和衰退中明显的相当大的变异性。最后，用这种方法确定的LTH相关因子将被实验操纵，以确定它们在LTH记忆的表达和衰减中的偶然作用。本项目提供了一种易于操作的方法，在实验背景下获得对长期记忆机制的基本见解，为本科生参与提供了极好的机会。

DESCRIPTION (provided by applicant): Learning produces long-term changes in behavior, physiology, and gene expression. Although this principle is now well-documented across the animal kingdom, fundamental aspects of learning and memory remain unclear: 1) how physiological and genetic changes supporting long-term memory are integrated across a neural circuit. 2) if forgetting represents the decay of long-term memory processes or an active erasure process, and 3) how individual differences in memory acquisition and retention arise. To address these fundamental issues in learning and memory, we propose a simple set of experiments using long-term habituation of the Aplysia tail-elicited siphon-withdrawal reflex (T-SWR). Groups of animals will be exposed to long-term habituation training (5 blocks of 30 stimuli applied to one side of the tail, 30s ISI, 90 min between blocks). This training produces a long-lasting and unilateral decrease in T-SWR behavior. To determine the physiological correlates of LTH, trained animals will be anesthetized and reduced to a siphon+tail preparation, enabling physiological recordings from the T-SWR circuit during ongoing behavior. By comparing tail-evoked neural activity from the trained and untrained side of each animal, it will be possible to identify sites of long- term neural plasticity elicited by LTH training. After physiological recordings, neurons from trained and untrained sides of each layer of the T-SWR circuit will be physically isolated. To determine the molecular correlates of LTH, RNA from harvested cells will be extracted, reverse-transcribed, and profiled using microarrays. By repeating this same procedure with animals harvested 1 and 7 days after training, it will be possible to determine physiological and genetic correlates of a memory expression (1 day) and decay (7 days). In addition, within group analyses will enable identification of physiological and transcriptional factors that predict the considerable variability evident in the acquisition and decay of long-term habituation. Finally, LTH correlates identified with this approach will be experimentally manipulated to determine their casual role in the expression and decay of LTH memory. This project provides a tractable means to gain fundamental insight into the mechanisms of long-term memory in an experimental context that offers excellent opportunities for undergraduate involvement. PUBLIC HEALTH RELEVANCE: This project will explore the genetic and neural changes that mediate long-term memory for habituation, a simple form of memory that is shared across the entire animal kingdom. By studying the mechanisms of habituation in a simple model organism (Aplysia californica), it will be possible to gain fundamental insight into the processes by memories are stored and subsequently decay. Results may have implications not only for the treatment of memory disorders, but also for a variety of attentional processes thought to depend on habituation.