We examined oscillatory power in electroencephalographic recordings obtained while younger (18-30 years) and older (60+ years) adults studied lists of words for later recall. Power changed in a highly consistent way from word-to-word across the study period. Above 14 Hz, there were virtually no age differences in these neural gradients. But gradients below 14 Hz reliably discriminated between age groups. Older adults with the best memory performance showed the largest departures from the younger adult pattern of neural activity. These results suggest that age differences in the dynamics of neural activity across an encoding period reflect changes in cognitive processing that may compensate for age-related decline.
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Age Differences In Retrieval-Related Reinstatement Reflect Age-Related Dedifferentiation At Encoding
Abstract Age-related reductions in neural selectivity have been linked to cognitive decline. We examined whether age differences in the strength of retrieval-related cortical reinstatement could be explained by analogous differences in neural selectivity at encoding, and whether reinstatement was associated with memory performance in an age-dependent or an age-independent manner. Young and older adults underwent fMRI as they encoded words paired with images of faces or scenes. During a subsequent scanned memory test participants judged whether test words were studied or unstudied and, for words judged studied, also made a source memory judgment about the associated image category. Using multi-voxel pattern similarity analyses, we identified robust evidence for reduced scene reinstatement in older relative to younger adults. This decline was however largely explained by age differences in neural differentiation at encoding; moreover, a similar relationship between neural selectivity at encoding and retrieval was evident in young participants. The results suggest that, regardless of age, the selectivity with which events are neurally processed at the time of encoding can determine the strength of retrieval-related cortical reinstatement.
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- Award ID(s):
- 1633873
- NSF-PAR ID:
- 10198411
- Date Published:
- Journal Name:
- Cerebral Cortex
- ISSN:
- 1047-3211
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Objectives Evidence from industrialized populations suggests that urine concentrating ability declines with age. However, lifestyle factors including episodic protein intake and low hypertension may help explain differences between populations. Whether this age‐related decline occurs among small‐scale populations with active lifestyles and non‐Western diets is unknown. We test the universality of age‐related urine concentration decline.
Materials and Methods We used urine specific gravity (Usg) and urine osmolality (Uosm) data from 15,055 U.S. nonpregnant adults without kidney failure aged 18–80 in 2007–2012 participating in the National Health and Nutrition Examination Survey (NHANES). We tested the relationship of age on urine concentration biomarkers with multiple linear regressions using survey commands. We compared results to longitudinal data on Usg from 116 Tsimane’ forager‐horticulturalists (266 observations) adults aged 18–83 in 2013–2014 from Lowland Bolivia, and to 38 Hadza hunter‐gatherers (156 observations) aged 18–75 in 2010–2015 from Tanzania using random‐effects panel linear regressions.
Results Among U.S. adults, age was significantly negatively associated with Usg (Adjusted beta [B] = −0.0009 g/mL/10 years; SE = 0.0001;
p < 0.001) and Uosm (B = −28.1 mOsm/kg/10 yr; SE = 2.4; p < 0.001). In contrast, among Tsimane’ (B = 0.0003 g/mL/10 yr; SE = 0.0002;p = 0.16) and Hadza (B = −0.0004 g/mL/10 yr; SE = 0.0004;p = 0.29) age was not associated with Usg. Older Tsimane’ and Hadza exhibited similar within‐individual variability in Usg equivalent to younger adults.Discussion While U.S. adults exhibited age‐related declines in urine concentration, Tsimane’ and Hadza adults did not exhibit the same statistical decline in Usg. Mismatches between evolved physiology and modern environments in lifestyle may affect kidney physiology and disease risk.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/cercor/bhaa210
