BEHV AND IMAGING APPROCHES TO IMPLICIT MEMORY IN AGING

我们提出了一套精心整合和理论驱动的行为和神经成像研究，旨在拓宽和深化当前对年龄相关内隐记忆变化的理解。大多数研究报告说，内隐记忆在一个年龄段内随着年龄和时间的推移而被保存，而外显记忆在老年受试者中下降。然而，一些具有挑衅性的发现已经被报道，表明某些类型的刺激和时间延迟导致内隐记忆丧失。使用可能/不可能对象决策启动任务，我们发现，无论是年轻人还是老年人，对已研究的可能对象的决策准确性都有显著的促进或启动作用，但对未研究的可能对象的决定准确性没有显著影响。然而，年轻的受试者在学习一周后仍然表现出启动，而老年人在20分钟后几乎消失了启动。这一关于老年人知觉记忆系统恶化的建议构成了我们拟议工作的一个中心主题。特别是，需要解决的假设是，熟悉的或先前存在的表征可以被年长的人内隐记忆；而对新表征的内隐记忆可能会随着时间的推移而恶化。我们的策略将是通过行为研究建立行为方法和发现，然后尝试通过后续的H_215O PET研究来探索支持这些任务的神经底物。因此，从第一年开始，我们将进行一系列6个行为实验，旨在测试我们的假设，最终将在一项研究中使用训练程序试图诱导熟悉我们的新刺激，以便直接改善老年人的延迟内隐记忆表现。从第二年开始，我们将进行一系列的正电子发射计算机断层扫描研究，以跟进行为研究，并评估支持编码和提取内隐记忆的神经底物，包括立即编码和延迟提取的年轻人和老年人。这一建议代表了合作者之间独特的专业知识组合，并将对我们理解与年龄相关的记忆变化做出重大贡献。

We propose a carefully integrated and theoretically-motivated set of behavioral and neuroimaging studies designed both to broaden and deepen current understanding of age-related changes in implicit memory. Most studies report that implicit memory is preserved over chronological age as well as across time within an age group, whereas explicit memory declines in elderly subjects. However, some provocative findings have been reported, showing implicit memory loss with certain types of stimuli, and over temporal delays. Using a possible/impossible object decision priming task, we found that decision accuracy was significantly facilitated or primed for studied, but not for non-studied possible objects in both young and elderly subjects. However, young subjects continued to show priming up to 1 week after study, whereas priming virtually disappeared for the elders after 20 minutes. This suggestion of a deteriorating perceptual memory system in the elderly constitutes a central theme in our proposed work. In particular, the hypothesis to be addressed is that familiar or pre-existing representations can be remembered implicitly by older individuals; whereas implicit memory for novel representations may deteriorate over time. Our strategy will be to establish behavioral methodology and findings with behavioral studies, and then to attempt to explore the neural substrates that support these tasks with followup H215O PET studies. Thus, beginning in year 1, we will conduct a series of 6 behavioral experiments designed to test our hypotheses, culminating in a study where we will use a training procedure to try to induce familiarity in our novel stimuli in order to directly improve delayed implicit memory performance in elders. Beginning in year 2, we will conduct a series of PET studies to follow up on the behavioral studies and assess the neural substrates supporting encoding and retrieval of implicit memory both immediately and at delays in young and older individuals. This proposal represents a unique combination of expertise across collaborators and will make a major contribution to our understanding of age-related changes in memory.