Age-associated non-selective neural activations

描述（由申请人提供）：拟议的项目旨在研究在情节记忆任务中老年人半球不对称减少的性质。在目前的项目中，提出了三个事件相关的功能磁共振成像实验，试图表征功能机制和认知过程介导的年龄相关的非选择性神经激活（即招聘的大脑区域以外的年轻人从事）。出现了两种观点来解释这种与年龄相关的神经激活。根据补偿观点，年龄相关的半球不对称性减少可能有助于抵消年龄相关的神经认知下降。根据去分化的观点，年龄相关的不对称性减少反映了招募专门的神经机制的困难。为了区分这些观点，我们联合收割机结合了多种方法，包括受试者之间的比较（即高功能与低功能的老年人），受试者内的比较（例如随后记住与随后忘记的项目），以及在检索需求方面不同的条件的比较。在实验1中，我们试图通过在一个单一的实验中结合受试者内和受试者间的比较，来调和在以前的情景编码研究中观察到的结果。在实验2中，我们探讨检索相关的神经激活在不同的条件下检索需求的年轻人。在实验3中，我们使用任务（即，联想识别），对MTL的要求比以前用来检查这个问题的任务更高。

DESCRIPTION (provided by applicant): The proposed project aims to examine the nature of hemispheric asymmetry reductions in older adults during tasks of episodic memory. In the current project, three event-related fMRI experiments are proposed which attempt to characterize the functional mechanisms and cognitive processes mediating age-related non-selective neural activations (i.e. recruitment of brain regions beyond those engaged by young adults). Two views have emerged to account for such age-associated neural activations. By the compensation view, age-related hemispheric asymmetry reductions may help to counteract age-related neurocognitive decline. According to the dedifferentiation view, age-related asymmetry reductions reflect a difficulty in recruiting specialized neural mechanisms. To differentiate between these views, we combine a variety of methods, including between-subjects comparisons, (i.e. high- versus low-functioning older adults), within-subject comparisons (e.g. subsequently remembered versus subsequently forgotten items), and comparisons of conditions which vary in their retrieval demand. In Experiment 1, we attempt to reconcile the results observed in previous episodic encoding studies of aging by combining within- and between-subjects comparisons in a single experiment. In Experiment 2, we explore retrieval-related neural activations in young adults under conditions which differ in retrieval demand. In Experiment 3, we investigate whether age-related non-selective activations extend to medial-temporal lobe (MTL) regions using a task (i.e., associative recognition) that places greater demands on the MTL than tasks previously used to examine this issue.