Effects of age on the strategic control of recollected content as reflected by modulation of neural correlates of scene retrieval.

A previous study employing fMRI measures of retrieval-related neural selectivity reported that young, but not older, adults employ 'retrieval gating' to attenuate aspects of an episodic memory that are irrelevant to the retrieval goal. We examined whether the weak memories of the older adults in that study rendered goal-irrelevant memories insufficiently intrusive to motivate retrieval gating. Young and older participants studied words superimposed on rural or urban scenes, or on scrambled backgrounds. To strengthen memory for background information, word-image pairs were studied twice, initially centrally, and then in one of three locations. During scanning, one retrieval test probed memory for the test words' studied backgrounds and another test assessed memory for their location. Background memory performance was markedly higher than in the prior study. Retrieval gating was examined in two scene-selective regions of interest, the parahippocampal place area (PPA) and the medial place area (MPA). In the background task, robust scene-specific retrieval effects were identified in both age groups in both ROIs. These effects were attenuated ('gated') in the location task in the young age group only, replicating the prior finding. The results did not differ when the two groups were sub-sampled to match strength of scene-specific retrieval effects when scene information was goal relevant. The findings indicate that older adults' failure to gate goal-irrelevant scene information does not reflect age differences in memory strength and may instead reflect an age-related decline in top-down inhibitory control.