scholarly journals Neural distinctiveness declines with age in auditory cortex and is associated with auditory GABA levels

2018 ◽  
Author(s):  
Poortata Lalwani ◽  
Holly Gagnon ◽  
Kaitlin Cassady ◽  
Molly Simmonite ◽  
Scott Peltier ◽  
...  
Keyword(s):  
Older Adults ◽  
Visual Cortex ◽  
Individual Differences ◽  
Magnetic Resonance ◽  
Auditory Cortex ◽  
Aging Brain ◽  
Resonance Spectroscopy ◽  
Younger Adults ◽  
Activation Patterns ◽  
Age Related

AbstractNeural activation patterns in the ventral visual cortex in response to different categories of visual stimuli (e.g., faces vs. houses) are less selective, or distinctive, in older adults than in younger adults, a phenomenon known as age-related neural dedifferentiation. Previous work in animals suggests that age-related reductions of the inhibitory neurotransmitter, gamma aminobutyric acid (GABA), may play a role in this age-related decline in neural distinctiveness. In this study, we investigated whether neural dedifferentiation extends to auditory cortex and whether individual differences in GABA are associated with individual differences in neural distinctiveness in humans. 20 healthy young adults (ages 18-29) and 23 healthy older adults (over 65) completed a functional magnetic resonance imaging (fMRI) scan, during which neural activity was estimated while they listened to foreign speech and music. GABA levels in the auditory, ventrovisual and sensorimotor cortex were estimated in the same individuals in a separate magnetic resonance spectroscopy (MRS) scan. Relative to the younger adults, the older adults exhibited both (1) less distinct activation patterns for music vs. speech stimuli and (2) lower GABA levels in the auditory cortex. Also, individual differences in auditory GABA levels (but not ventrovisual or sensorimotor GABA levels) predicted individual differences in neural distinctiveness in the auditory cortex in the older adults. These results demonstrate that age-related neural dedifferentiation extends to the auditory cortex and suggest that declining GABA levels may play a role in neural dedifferentiation in older adults.Significance StatementPrior work has revealed age-related neural dedifferentiation in the visual cortex. GABA levels also decline with age in several parts of the human cortex. Here, we report that these two age-related changes are linked; neural dedifferentiation is associated with lower GABA levels in older adults. We also show that age-related neural dedifferentiation extends to auditory cortex, suggesting that it may be a general feature of the aging brain. These findings provide novel insights into the neurochemical basis of age-related neural dedifferentiation in humans and also offer a potential new avenue for investigating age-related declines in central auditory processing.

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

2019 ◽  
Author(s):  
Jordan D. Chamberlain ◽  
Holly Gagnon ◽  
Poortata Lalwani ◽  
Kaitlin E. Cassady ◽  
Molly Simmonite ◽  
...  
Keyword(s):  
Older Adults ◽  
Visual Cortex ◽  
Magnetic Resonance ◽  
Aminobutyric Acid ◽  
Resonance Spectroscopy ◽  
Gamma Aminobutyric Acid ◽  
Younger Adults ◽  
Inhibitory Neurotransmitter ◽  
Neural Representations ◽  
Age Related

AbstractAge-related neural dedifferentiation – reduced distinctiveness of neural representations in the aging brain– has been associated with age-related declines in cognitive abilities. But why does neural distinctiveness decline with age? Based on prior work in non-human primates, we hypothesized that the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) declines with age and is associated with neural dedifferentiation. To test this hypothesis, we used magnetic resonance spectroscopy (MRS) to measure GABA and functional MRI (fMRI) to measure neural distinctiveness in the ventral visual cortex in a set of older and younger participants. Relative to younger adults, older adults exhibited lower GABA levels and less distinct activation patterns for faces and houses in the ventral visual cortex. Furthermore, individual differences in GABA within older adults predicted individual differences in neural distinctiveness even after controlling for gray matter volume and age. These results provide novel support for the view that age-related reductions of GABA contribute to age-related reductions in neural distinctiveness (i.e., neural dedifferentiation) in the human ventral visual cortex.Significance StatementNeural representations in the ventral visual cortex are less distinguishable in older compared to younger humans, and this neural dedifferentiation is associated with age-related cognitive deficits. Animal models suggest that reductions in the inhibitory neurotransmitter gamma aminobutyric acid (GABA) may play a role. To investigate this hypothesis, we combined functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy (MRS) in a study of the human ventral visual cortex. We observed reduced distinctiveness of neural patterns and reduced GABA levels in older compared to younger adults. Furthermore, older adults with higher GABA levels tended to have more distinctive neural representations. These findings suggest that reduced GABA levels contribute to age-related declines in neural distinctiveness in the human ventral visual cortex.

scholarly journals Advanced Aging Enhances the Positivity Effect in Memory: Due to Cognitive Control or Age-Related Decline in Emotional Processing?

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Michiko Sakaki ◽  
Jasmine A. L. Raw ◽  
Jamie Findlay ◽  
Mariel Thottam
Keyword(s):  
Older Adults ◽  
Cognitive Control ◽  
Emotional Processing ◽  
Aging Brain ◽  
Control Mechanisms ◽  
Younger Adults ◽  
Positivity Effect ◽  
Old Adults ◽  
Age Related ◽  
Conditioned Responses

Older adults typically remember more positive than negative information compared to their younger counterparts; a phenomenon referred to as the ‘positivity effect.’ According to the socioemotional selectivity theory (SST), the positivity effect derives from the age-related motivational shift towards attaining emotionally meaningful goals which become more important as the perception of future time becomes more limited. Cognitive control mechanisms are critical in achieving such goals and therefore SST predicts that the positivity effect is associated with preserved cognitive control mechanisms in older adults. In contrast, the aging-brain model suggests that the positivity effect is driven by an age-related decline in the amygdala which is responsible for emotional processing and emotional learning. The aim of the current research was to address whether the age-related positivity effect is associated with cognitive control or impaired emotional processing associated with aging. We included older old adults, younger old adults and younger adults and tested their memory for emotional stimuli, cognitive control and amygdala-dependent fear conditioned responses. Consistent with prior research, older adults, relative to younger adults, demonstrate better memory for positive over negative images. We further found that within a group of older adults, the positivity effect increases as a function of age, such that older old adults demonstrated a greater positivity effect compared to younger older adults. Furthermore, the positivity effect in older old adults was associated with preserved cognitive control, supporting the prediction of SST. Contrary to the prediction of the aging-brain model, participants across all groups demonstrated similar enhanced skin conductance responses to fear conditioned stimuli – responses known to rely on the amygdala. Our results support SST and suggest that the positivity effect in older adults is achieved by the preserved cognitive control mechanisms and is not a reflection of the impaired emotional function associated with age.

scholarly journals Event Centrality of Positive and Negative Autobiographical Memories in Older Adulthood

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 712-712
Author(s):  
Justina Pociunaite ◽  
Tabea Wolf
Keyword(s):  
Older Adults ◽  
Individual Differences ◽  
Life Experience ◽  
Age Groups ◽  
Openness To Experience ◽  
Middle Aged ◽  
Younger Adults ◽  
Age Related ◽  
Middle Aged Adults ◽  
Positive Memories

Abstract Centrality of an event (CE) is a characteristic denoting how important a life experience is to one’s identity. Usually, positive memories are more central than negative ones in the community samples. Nevertheless, there is emerging evidence showing substantial individual differences in how one perceives CE. Especially regarding age, one could expect pronounced differences due to age-related changes in personal goals. In this study, we investigated how older adults differ from young and middle-aged adults. Apart from age, we tested whether personality traits such as neuroticism and openness to experience influence the CE ratings among age groups. The sample comprised of 363 German participants, age ranging from 18 to 89 (M=49.57, SD=17.087), 67.2 % of the sample were women. Using multilevel analysis, we found the CE of positive memories to be higher in all age groups. The CE of positive events significantly differed for older adults compared to younger adults but not to the middle-aged group. With respect to personality, neuroticism had an impact only on the CE of negative memories in younger and middle-aged adults. For older adults, neither neuroticism, nor openness to experience had an impact on CE ratings. This shows that while older adults significantly differ from younger adults in the CE of positive memories, other individual differences characteristics do not have an impact on the way older adults perceive memories as central to their identity.

In Vivo Brain Glutathione is Higher in Older Age and Correlates with Mobility

2020 ◽  
Author(s):  
K. E. Hupfeld ◽  
H. W. Hyatt ◽  
P. Alvarez Jerez ◽  
M. Mikkelsen ◽  
C. J. Hass ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Older Adults ◽  
Motor Performance ◽  
Resonance Spectroscopy ◽  
Younger Adults ◽  
Age Related ◽  
Brain Oxidative Stress ◽  
Brain Antioxidants ◽  
Insight Into

AbstractBrain markers of oxidative damage increase with advancing age. In response, brain antioxidant levels may also increase with age, although this has not been well investigated. Here we used edited magnetic resonance spectroscopy to quantify endogenous levels of glutathione (GSH, one of the most abundant brain antioxidants) in 37 young (mean: 21.8 (2.5) years; 19 F) and 23 older adults (mean: 72.8 (8.9) years; 19 F). Accounting for age-related atrophy, we identified higher frontal and sensorimotor GSH levels for the older compared to the younger adults. For the older adults only, higher sensorimotor (but not frontal) GSH was correlated with poorer balance, gait, and manual dexterity. This suggests a regionally-specific relationship between higher brain oxidative stress levels and motor performance declines with age. We suggest these findings reflect a compensatory upregulation of GSH in response to increasing brain oxidative stress with normal aging. Together, these results provide insight into age differences in brain antioxidant levels and implications for motor function.

scholarly journals Age-Associated Reduction of Asymmetry in Human Central Auditory Function: A 1H-Magnetic Resonance Spectroscopy Study

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Xianming Chen ◽  
Yonghui Liang ◽  
Yihong Deng ◽  
Jianzhong Li ◽  
Shiyan Chen ◽  
...  
Keyword(s):  
Older Adults ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Auditory Cortex ◽  
Pure Tone ◽  
Hemispheric Asymmetry ◽  
Young Group ◽  
Resonance Spectroscopy ◽  
1H Magnetic Resonance Spectroscopy ◽  
Left And Right

The aim of this study was to investigate the effects of age on hemispheric asymmetry in the auditory cortex after pure tone stimulation. Ten young and 8 older healthy volunteers took part in this study. Two-dimensional multivoxel 1H-magnetic resonance spectroscopy scans were performed before and after stimulation. The ratios of N-acetylaspartate (NAA), glutamate/glutamine (Glx), andγ-amino butyric acid (GABA) to creatine (Cr) were determined and compared between the two groups. The distribution of metabolites between the left and right auditory cortex was also determined. Before stimulation, left and right side NAA/Cr and right side GABA/Cr were significantly lower, whereas right side Glx/Cr was significantly higher in the older group compared with the young group. After stimulation, left and right side NAA/Cr and GABA/Cr were significantly lower, whereas left side Glx/Cr was significantly higher in the older group compared with the young group. There was obvious asymmetry in right side Glx/Cr and left side GABA/Cr after stimulation in young group, but not in older group. In summary, there is marked hemispheric asymmetry in auditory cortical metabolites following pure tone stimulation in young, but not older adults. This reduced asymmetry in older adults may at least in part underlie the speech perception difficulties/presbycusis experienced by aging adults.

scholarly journals Older adults benefit from more widespread brain network integration during working memory

2019 ◽  
Author(s):  
C.A. Crowell ◽  
S.W. Davis ◽  
L. Beynel ◽  
L. Deng ◽  
D. Lakhlani ◽  
...  
Keyword(s):  
Older Adults ◽  
Working Memory ◽  
Network Connectivity ◽  
Task Demands ◽  
Global Network ◽  
Aging Brain ◽  
Network Integration ◽  
Younger Adults ◽  
Age Related ◽  
Cortical Regions

AbstractNeuroimaging evidence suggests that the aging brain relies on a more distributed set of cortical regions than younger adults in order to maintain successful levels of performance during demanding cognitive tasks. However, it remains unclear how task demands give rise to this age-related expansion in cortical networks. To investigate this issue, we used functional magnetic resonance imaging to measure univariate activity, network connectivity, and cognitive performance in younger and older adults during a working memory (WM) task. In the WM task investigated, participants hold letters online (maintenance) while reordering them alphabetically (manipulation). WM load was titrated to obtain four individualized difficulty levels. Network integration—defined as the ratio of within-versus between-network connectivity—was linked to individual differences in WM capacity. The study yielded three main findings. First, as task difficulty increased, network integration decreased in younger adults, whereas it increased in older adults. Second, age-related increases in network integration were driven by increases in right hemispheric connectivity to both left and right cortical regions, a finding that helps to reconcile extant theories of compensatory recruitment in aging to address the multivariate dynamics of global network functioning. Lastly, older adults with higher WM capacity demonstrated higher levels of network integration in the most difficult condition. These results shed light on the mechanisms of age-related network reorganization by suggesting that changes in network connectivity may act as an adaptive form of compensation, with older adults recruiting a more distributed cortical network as task demands increase.Significance statementOlder adults often activate brain regions not engaged by younger adults, but the circumstances under which this widespread network emerges are unclear. Here, we examined the effects of aging on network connectivity between task regions recruited during a working memory (WM) manipulation task, and the rest of the brain. We found an age-related increase in the more global network integration in older adults, and an association between this integration and working memory capacity in older adults. The findings are generally consistent with the compensatory interpretation of these effects.

scholarly journals Linking individual differences in cognitive control and perception: Meta-perception in older and younger adults

2021 ◽  
Author(s):  
Lena Klever ◽  
Pascal Mamassian ◽  
Jutta Billino
Keyword(s):  
Older Adults ◽  
Individual Differences ◽  
Cognitive Control ◽  
Age Groups ◽  
Age Effects ◽  
Younger Adults ◽  
Age Related ◽  
Perceptual Performance ◽  
Metacognitive Ability ◽  
Specific Challenge

Visual perception is not only shaped by sensitivity, but also by confidence, i.e. the ability to estimate the accuracy of a visual decision. There is robust evidence that younger observers have access to a reliable measure of their own uncertainty when making visual decisions. This metacognitive ability might be challenged during aging due to increasing sensory noise and decreasing cognitive control resources. We investigated age effects on visual confidence using a confidence forced-choice paradigm. We determined discrimination thresholds for trials in which perceptual judgements were indicated as confident and for those in which they were declined as confident. Younger adults (19-38 years) showed significantly lower discrimination thresholds than older adults (60-78 years). In both age groups, perceptual performance was linked to confidence judgements, but overall results suggest reduced confidence efficiency in older adults. However, we observed substantial variability of confidence effects across all particpants. This variability was closely linked to individual differences in cognitive control capacities, i.e. executive function. Our findings provide evidence for age-related differences in meta-perceptual efficiency that present a specific challenge to perceptual performance in old age. We propose that these age effects are primarily mediated by cognitive control resources, supporting their crucial role for metacognitive efficiency.

scholarly journals A Neural Signature of Regularity in Sound is Reduced in Older Adults

2021 ◽  
Author(s):  
Björn Herrmann ◽  
Burkhard Maess ◽  
Ingrid S. Johnsrude
Keyword(s):  
Older Adults ◽  
Auditory Cortex ◽  
Older Individuals ◽  
Sound Perception ◽  
Younger Adults ◽  
Sound Processing ◽  
Age Related ◽  
Increased Sensitivity ◽  
Neural Signature ◽  
Age Related Changes

AbstractSensitivity to repetitions in sound amplitude and frequency is crucial for sound perception. As with other aspects of sound processing, sensitivity to such patterns may change with age, and may help explain some age-related changes in hearing such as segregating speech from background sound. We recorded magnetoencephalography to characterize differences in the processing of sound patterns between younger and older adults. We presented tone sequences that either contained a pattern (made of a repeated set of tones) or did not contain a pattern. We show that auditory cortex in older, compared to younger, adults is hyperresponsive to sound onsets, but that sustained neural activity in auditory cortex, indexing the processing of a sound pattern, is reduced. Hence, the sensitivity of neural populations in auditory cortex fundamentally differs between younger and older individuals, overresponding to sound onsets, while underresponding to patterns in sounds. This may help to explain some age-related changes in hearing such as increased sensitivity to distracting sounds and difficulties tracking speech in the presence of other sound.

scholarly journals Effects of Aging on the Encoding of Spatial Direction in the Human Brain

2019 ◽  
Author(s):  
Christoph Koch ◽  
Shu-Chen Li ◽  
Thad A. Polk ◽  
Nicolas W. Schuck
Keyword(s):  
Older Adults ◽  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Age Differences ◽  
Spatial Navigation ◽  
Activation Patterns ◽  
Directional Information ◽  
Spatial Direction ◽  
Age Related ◽  
Pattern Similarity

AbstractHuman aging is characterized by impaired spatial cognition and reductions in the distinctiveness of category-specific fMRI activation patterns. Yet, little is know about age-related decline in neural distinctiveness of spatial information. Here, we asked whether neural tuning functions of walking direction are broadened in older versus younger adults. To test this idea, we developed a novel method that allowed us to investigate changes in fMRI-measured pattern similarity while participants navigated in different directions in a virtual spatial navigation task. We expected that directional tuning functions would be broader in older adults, and thus activation patterns that reflect neighboring directions would be less distinct as compared to non-adjacent directions. Because loss of distinctiveness leads to more confusions when information is read out by downstream areas, we analyzed predictions of a decoder trained on these representations and asked (1) whether decoder confusions between two directions increase proportionally to their angular similarity, (2) and how this effect may differ between age groups. Evidence for tuning-function-like signals was found in the retrosplenial complex and primary visual cortex. Significant age differences in tuning width, however, were only found in the primary visual cortex, suggesting that less precise visual information could lead to worse directional signals in older adults. Yet, age differences in visual tuning were not related to behavior. Instead, directional information encoded in RSC correlated with memory on task. These results shed new light on neural mechanisms underling age-related spatial navigation impairments and introduce a novel approach to measure tuning specificity using fMRI.

Age-Related Differences in Motivational Integration and Cognitive Control

2019 ◽  
Author(s):  
Debbie Marianne Yee ◽  
Sarah L Adams ◽  
Asad Beck ◽  
Todd Samuel Braver
Keyword(s):  
Older Adults ◽  
Decision Making ◽  
Cognitive Control ◽  
Task Performance ◽  
Cognitive Task ◽  
Monetary Reward ◽  
Potential Candidate ◽  
Younger Adults ◽  
Age Related ◽  
Cognitive Task Performance

Motivational incentives play an influential role in value-based decision-making and cognitive control. A compelling hypothesis in the literature suggests that the brain integrates the motivational value of diverse incentives (e.g., motivational integration) into a common currency value signal that influences decision-making and behavior. To investigate whether motivational integration processes change during healthy aging, we tested older (N=44) and younger (N=54) adults in an innovative incentive integration task paradigm that establishes dissociable and additive effects of liquid (e.g., juice, neutral, saltwater) and monetary incentives on cognitive task performance. The results reveal that motivational incentives improve cognitive task performance in both older and younger adults, providing novel evidence demonstrating that age-related cognitive control deficits can be ameliorated with sufficient incentive motivation. Additional analyses revealed clear age-related differences in motivational integration. Younger adult task performance was modulated by both monetary and liquid incentives, whereas monetary reward effects were more gradual in older adults and more strongly impacted by trial-by-trial performance feedback. A surprising discovery was that older adults shifted attention from liquid valence toward monetary reward throughout task performance, but younger adults shifted attention from monetary reward toward integrating both monetary reward and liquid valence by the end of the task, suggesting differential strategic utilization of incentives. Together these data suggest that older adults may have impairments in incentive integration, and employ different motivational strategies to improve cognitive task performance. The findings suggest potential candidate neural mechanisms that may serve as the locus of age-related change, providing targets for future cognitive neuroscience investigations.

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