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.
| Giovanello, Kelly S; Schacter, Daniel L (2012) Reduced specificity of hippocampal and posterior ventrolateral prefrontal activity during relational retrieval in normal aging. J Cogn Neurosci 24:159-70 |
| Giovanello, Kelly S; Kensinger, Elizabeth A; Wong, Alana T et al. (2010) Age-related neural changes during memory conjunction errors. J Cogn Neurosci 22:1348-61 |
