Although memory recall is known to be reduced with normal aging, little is known about the patterns of brain activity that accompany these recall failures. By assessing faulty memory, we can identify the brain regions engaged during retrieval attempts in the absence of successful memory and determine the impact of aging on this functional activity. We used functional magnetic resonance imaging to examine age differences in brain activity associated with memory failure in three memory retrieval tasks: autobiographical (AM), episodic (EM) and semantic (SM). Compared to successful memory retrieval, both age groups showed more activity when they failed to recall a memory in regions consistent with the salience network (SLN), a brain network also associated with non-memory errors. Both groups also showed strong functional coupling among SLN regions during incorrect trials and in intrinsic patterns of functional connectivity. In comparison to young adults, older adults demonstrated (1) less activity within the SLN during unsuccessful AM trials; (2) weaker intrinsic functional connectivity between SLN nodes and dorsolateral prefrontal cortex; and (3) less differentiation of SLN functional connectivity during incorrect trials across memory conditions. These results suggest that the SLN is engaged during recall failures, as it is for non-memory errors, which may be because errors in general have particular salience for adapting behavior. In older adults, the dedifferentiation of functional connectivity within the SLN across memory conditions and the reduction of functional coupling between it and prefrontal cortex may indicate poorer internetwork communication and less flexible use of cognitive control processes, either while retrieval is attempted or when monitoring takes place after retrieval has failed. Keywords fMRI; aging; episodic memory; salience network; frontal lobe
IntroductionA number of studies have provided extensive evidence of the neural circuitry that supports memory retrieval (e.g., Cabeza and Nyberg, 2000;Spaniol et al., 2009
CIHR Author Manuscript
CIHR Author Manuscript
CIHR Author Manuscript2008), as well as evidence of how aging influences this circuitry (e.g., Cabeza et al., 2005;Grady, 2012;Rajah and D'Esposito, 2005). However, most research has investigated how the brain supports successful memory performance (Addis and McAndrews, 2006;Brewer et al., 1998;Morcom et al., 2003;Wagner et al., 1998), and limited attention has been paid to brain networks involved in faulty memory retrieval, most notably faulty long-term memory recall. A number of processes may be engaged during recall, including goal setting, memory search, accessing (hopefully correct) stored memories, and evaluating retrieval success (Henson et al., 1999;Moscovitch, 1992;Rugg et al., 2002). The assessment of faulty memory retrieval can be used to identify brain regions whose activity reflects processes engaged when retrieval fails. Such processes can include cognitive control processes involved regardless of retrieval succes...