The effects of aging on material-independent and material-dependent neural correlates of source memory retrieval - PubMed (original) (raw)
The effects of aging on material-independent and material-dependent neural correlates of source memory retrieval
Michael R Dulas et al. Cereb Cortex. 2012 Jan.
Abstract
Age-related declines in source memory have been observed for various stimuli and associated details. These impairments may be related to alterations in brain regions contributing to source memory via material-independent processes and/or regions specialized for processing specific materials. Using event-related functional magnetic resonance imaging, we investigate the effects of aging on source memory and associated neural activity for words and objects. Source accuracy was equally impaired in older adults for both materials. Imaging data revealed both groups recruited similar networks of regions to support source memory accuracy irrespective of material, including parietal and prefrontal cortices (PFC) and the hippocampus. Age-related decreases in material-independent activity linked to postretrieval monitoring were observed in right lateral PFC. Additionally, age-related increases in source accuracy effects were shown in perirhinal cortex, which were positively correlated with performance in older adults, potentially reflecting functional compensation. In addition to group differences in material-independent regions, age-related crossover interactions for material-dependent source memory effects were observed in regions selectively engaged by objects. These results suggest that older adults' source memory impairments reflect alterations in regions making material-independent contributions to source memory retrieval, primarily the lateral PFC, but may be further impacted by changes in regions sensitive to particular materials.
Figures
Figure 1.
Old/new effects, (SC vs. CR). Activity common to groups and age-related interactions are shown. Select regions are displayed on the 3D rendered MNI reference brain (P < 0.0005, uncorrected, with a 5 voxel extent; exclusive masking conducted as described in Materials and Methods). YA, young; OA, old.
Figure 2.
Material-independent old/new effects. Activity common to groups and age-related interactions are shown. Select regions are displayed on the MNI reference brain. Plots show parameter estimates for the event-related response at the peak maxima of the selected regions for SC and CR trial types. Error bars depict standard error of the mean across participants, for each group. (P < 0.0005, uncorrected, with a 5 voxel extent; exclusive masking conducted as described in Materials and Methods). YA, young; OA, old.
Figure 3.
Regions exhibiting differential activity for words and objects, collapsed across memory judgment, are displayed on the 3D rendered MNI reference brain. Activity common to both groups and activity showing age-related interactions are shown (P < 0.0005, uncorrected, with a 5 voxel extent; exclusive masking conducted as described in Materials and Methods). YA, young; OA, old.
Figure 4.
Material-dependent old/new effects. Regions more sensitive to objects than words (see Fig. 3) are also shown to highlight the overlap between perceptual processing and memory effects. Select regions are displayed on the MNI reference brain. Plots show parameter estimates for the event-related response at the peak maxima of the selected regions for SC and CR trial types. Error bars depict standard error of the mean across participants, for each group. (P < 0.0005, uncorrected, with a 5 voxel extent; inclusive masking conducted as described in Materials and Methods). YA, young; OA, old.
Figure 5.
Material-independent source memory effects, specific to recollection (SC vs. SINCDK). Activity common to groups and age-related interactions are shown. Select regions are displayed on the MNI reference brain. Plots show parameter estimates for the event-related response at the peak maxima of the selected regions for SC and SINCDK trial types. Error bars depict standard error of the mean across participants, for each group. (P < 0.0005, uncorrected, with a 5 voxel extent; P < 0.05, FWE-corrected for the MTL regions; exclusive masking conducted as described in Materials and Methods). YA, young; OA, old.
Figure 6.
Correlations between source memory accuracy and activity in the PrC for both groups. YA, young; OA, old.
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