GABA levels in ventral visual cortex decline with age and are associated with neural distinctiveness

Chamberlain, Jordan D.; Gagnon, Holly; Lalwani, Poortata; Cassady, Kaitlin; Simmonite, Molly; Seidler, Rachael D.; Taylor, Stephan F.; Weissman, Daniel H.; Park, Denise C.; Polk, Thad A.

doi:10.1016/j.neurobiolaging.2021.02.013

Cited by 38 publications

(36 citation statements)

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“…Carp et al, (2011) evaluated the distinctiveness of distributed patterns of neural activation elicited by different categories of visual stimuli and found neural activation patterns in the ventral visual cortex were less distinct in older adults. Several other studies have used MVPA to replicate these findings of reduced age-related dedifferentiation at the level of category representations (Chamberlain et al, 2021; J. Park, Carp, Hebrank, Park, & Polk, 2010) and recently Kobelt et al, (2021) found that item-level distinctiveness was also reduced in older adults.…”

Section: Introductionmentioning

confidence: 77%

“…Previous neuroimaging research has employed univariate and multivariate techniques to demonstrate age-related neural dedifferentiation in sensory regions including the visual (Carp, Park, Polk, et al, 2011; Chamberlain et al, 2021; D. C. Park et al, 2004; J.…”

Section: Discussionmentioning

confidence: 99%

“…Another possibility is age-related changes in neurotransmitter systems. Both dopamine (Bäckman, Nyberg, Lindenberger, Li, & Farde, 2006) and gamma-aminobutyric acid (GABA) (Chamberlain et al, 2021; Lalwani et al, 2019) systems have been reported to be affected by age and to be associated with neural distinctiveness.…”

Section: Discussionmentioning

confidence: 99%

“…To assess neural distinctiveness, we used a correlation-based approach, in line with that used by Haxby et al (2000), Carp et al (2011), Lalwani et al (2019), Cassady et al (2020), and Chamberlain et al (2021). To do so, for each participant, in each task we compared patterns of neural activity that were elicited by different blocks of the same experimental condition, with neural activity elicited by blocks of different experimental conditions.…”

Section: Methodsmentioning

confidence: 99%

“…Carp et al, (2011) found age differences in both, with older adults exhibiting reduced within-category similarities and increased between-category similarities. Other evidence has demonstrated age-reductions in the reliability of representations at the level of individual items (Zheng et al, 2018) and categories, without a significant increase in between-category similarity (Chamberlain et al, 2021). Here we use data from the Michigan Neural Distinctiveness (MiND) project (Gagnon et al, 2019) to investigate that question in visual cortex, in auditory cortex, and in motor cortex.…”

Section: Introductionmentioning

confidence: 99%

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Age-related declines in neural distinctiveness correlate across brain areas and result from both decreased reliability and increased confusability

Simmonite

Polk

2021

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According to the neural dedifferentiation hypothesis, age-related reductions in the distinctiveness of neural representations contribute to sensory, cognitive, and motor declines associated with aging: neural activity associated with different stimulus categories becomes more confusable with age and behavioural performance suffers as a result. Initial studies investigated age-related dedifferentiation in the visual cortex, but subsequent research has revealed declines in other brain regions, suggesting that dedifferentiation may be a general feature of the aging brain. In the present study, we used functional magnetic resonance imaging to investigate age-related dedifferentiation in the visual, auditory, and motor cortices. Participants were 58 young adults and 79 older adults. The similarity of activation patterns across different blocks of the same condition was calculated (within-condition correlation, a measure of reliability) as was the similarity of activation patterns elicited by different conditions (between-category correlations, a measure of confusability). Neural distinctiveness was defined as the difference between the mean within- and between-condition similarity. We found age-related reductions in neural distinctiveness in the visual, auditory, and motor cortices, which were driven by both decreases in within-category similarity and increases in between-category similarity. There were significant positive cross-region correlations between neural distinctiveness in different regions. These correlations were driven by within-category similarities, a finding that indicates that declines in the reliability of neural activity appear to occur in tandem across the brain. These findings suggest that the changes in neural distinctiveness that occur in healthy aging result from changes in both the reliability and confusability of patterns of neural activity.

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