Effects of cortical thickness, volume, and memory performance on age differences in neural reinstatement of scene information.

The strength of neural reinstatement, a correlate of episodic memory retrieval, reportedly reflects the amount and fidelity of mnemonic content and is weaker in older than younger adults, especially for scene memoranda. Based on evidence that age-related declines in cortical thickness and volume contribute to age-related cognitive decline, we analyzed functional magnetic resonance imaging data acquired from healthy young and older adults to examine relationships between cortical thickness, cortical volume, age, and scene-related reinstatement in 3 cortical regions implicated in scene processing: the parahippocampal place area, medial place area, and occipital place area. A "reinstatement index" was estimated from functional magnetic resonance imaging data collected during tests of source memory for scene images, and multiple regression analyses were employed to examine the effects of the variables of interest on scene reinstatement. There were robust age differences in reinstatement, cortical thickness, and cortical volume. In the parahippocampal place area and medial place area, cortical volume fully mediated the effects of age on reinstatement. Additionally, parahippocampal place area reinstatement strength predicted source memory performance independently of cortical volume or age. These findings suggest that age differences in scene reinstatement are mediated by cortical volume and that memory performance and cortical volume are associated with unique components of variance in reinstatement strength.