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.

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 Electromyographic activation patterns during swallowing in older adults

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jin Young Ko ◽  
Hayoung Kim ◽  
Joonyoung Jang ◽  
Jun Chang Lee ◽  
Ju Seok Ryu
Keyword(s):  
Older Adults ◽  
Viscous Fluid ◽  
Muscle Activation ◽  
Fatty Infiltration ◽  
Liquid Volume ◽  
Type I ◽  
Type Ii ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Age Related

AbstractAge-related weakness due to atrophy and fatty infiltration in oropharyngeal muscles may be related to dysphagia in older adults. However, little is known about changes in the oropharyngeal muscle activation pattern in older adults. This was a prospective and experimental study. Forty healthy participants (20 older [> 60 years] and 20 young [< 60 years] adults) were enrolled. Six channel surface electrodes were placed over the bilateral suprahyoid (SH), bilateral retrohyoid (RH), thyrohyoid (TH), and sternothyroid (StH) muscles. Electromyography signals were then recorded twice for each patient during swallowing of 2 cc of water, 5 cc of water, and 5 cc of a highly viscous fluid. Latency, duration, and peak amplitude were measured. The activation patterns were the same, in the order of SH, TH, and StH, in both groups. The muscle activation patterns were classified as type I and II; the type I pattern was characterized by a monophasic shape, and the type II comprised a pre-reflex phase and a main phase. The oropharyngeal muscles and SH muscles were found to develop a pre-reflex phase specifically with increasing volume and viscosity of the swallowed fluid. Type I showed a different response to the highly viscous fluid in the older group compared to that in the younger group. However, type II showed concordant changes in the groups. Therefore, healthy older people were found to compensate for swallowing with a pre-reflex phase of muscle activation in response to increased liquid volume and viscosity, to adjust for age-related muscle weakness.

Age Differences in the Social Associative Learning of Trust Information

2022 ◽  
Author(s):  
Kendra Leigh Seaman ◽  
Alexander P. Christensen ◽  
Katherine Senn ◽  
Jessica Cooper ◽  
Brittany Shane Cassidy
Keyword(s):  
Older Adults ◽  
Age Differences ◽  
Social Cues ◽  
Trust Game ◽  
Time Model ◽  
Younger Adults ◽  
Cortical Areas ◽  
Age Related ◽  
The Social ◽  
Over Time

Trust is a key component of social interaction. Older adults, however, often exhibit excessive trust relative to younger adults. One explanation is that older adults may learn to trust differently than younger adults. Here, we examine how younger (N=33) and older adults (N=30) learn to trust over time. Participants completed a classic iterative trust game with three partners. Younger and older adults shared similar amounts but differed in how they shared money. Compared to younger adults, older adults invested more with untrustworthy partners and less with trustworthy partners. As a group, older adults displayed less learning than younger adults. However, computational modeling shows that this is because older adults are more likely to forget what they have learned over time. Model-based fMRI analyses revealed several age-related differences in neural processing. Younger adults showed prediction error signals in social processing areas while older adults showed over-recruitment of several cortical areas. Collectively, these findings suggest that older adults attend to and learn from social cues differently from younger adults.

scholarly journals Adult age differences in subjective responses to dynamic socioemotional incentives

2020 ◽  
Author(s):  
Sade J Abiodun ◽  
Galen McAllister ◽  
Gregory Russell Samanez-Larkin ◽  
Kendra Leigh Seaman
Keyword(s):  
Older Adults ◽  
Age Differences ◽  
Emotional Valence ◽  
Incentive Motivation ◽  
Social Signals ◽  
Younger Adults ◽  
Positivity Effect ◽  
Adult Age ◽  
Age Related ◽  
Adult Age Differences

Facial expressions are powerful communicative social signals that motivate feelings and action in the observer. However, research on incentive motivation has overwhelmingly focused on money and points and the limited research on social incentives has been mostly focused on responses in young adulthood. Previous research on the age-related positivity effect and adult age differences in social motivation suggest that older adults might experience higher levels of positive arousal to socioemotional stimuli than younger adults. Affect ratings following dynamic emotional expressions (anger, happiness, sadness) varying in magnitude of expression showed that higher magnitude expressions elicited higher arousal and valence ratings. Older adults did not differ significantly in levels of arousal when compared to younger adults, however their ratings of emotional valence were significantly higher as the magnitude of expressions increased. The findings provide novel evidence that socioemotional incentives may be relatively more reinforcing as adults age. More generally, these dynamic socioemotional stimuli that vary in magnitude are ideal for future studies of more naturalistic affect elicitation, studies of social incentive processing, and use in incentive-driven choice tasks.

scholarly journals Age Differences in the Required Coefficient of Friction During Level Walking Do Not Exist When Experimentally-Controlling Speed and Step Length

2014 ◽  
Vol 30 (4) ◽  
pp. 542-546 ◽  
Author(s):  
Dennis E. Anderson ◽  
Christopher T. Franck ◽  
Michael L. Madigan
Keyword(s):  
Older Adults ◽  
Age Differences ◽  
Coefficient Of Friction ◽  
Age Groups ◽  
Step Length ◽  
Age Difference ◽  
Age Related ◽  
Negative Effect ◽  
Independent Effects ◽  
Positive Effect

The effects of gait speed and step length on the required coefficient of friction (COF) confound the investigation of age-related differences in required COF. The goals of this study were to investigate whether age differences in required COF during self-selected gait persist when experimentally-controlling speed and step length, and to determine the independent effects of speed and step length on required COF. Ten young and 10 older healthy adults performed gait trials under five gait conditions: self-selected, slow and fast speeds without controlling step length, and slow and fast speeds while controlling step length. During self-selected gait, older adults walked with shorter step lengths and exhibited a lower required COF. Older adults also exhibited a lower required COF when walking at a controlled speed without controlling step length. When both age groups walked with the same speed and step length, no age difference in required COF was found. Thus, speed and step length can have a large influence on studies investigating age-related differences in required COF. It was also found that speed and step length have independent and opposite effects on required COF, with step length having a strong positive effect on required COF, and speed having a weaker negative effect.

scholarly journals USING VR FOR NAVIGATION ASSESSMENT IN OLDER ADULTS

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S240-S240
Author(s):  
Scott Moffat
Keyword(s):  
Older Adults ◽  
Age Differences ◽  
Large Scale ◽  
Empirical Studies ◽  
Science Research ◽  
Later Life ◽  
Functional Independence ◽  
Spatial Strategies ◽  
Age Related ◽  
Field Of Inquiry

Abstract There has been a long tradition of wayfinding and orienteering studies in humans but these have mostly neglected possible age-related differences in navigation. This field of inquiry is experiencing something of a resurgence of interest due to the development of VR technology which has brought the systematic study of large scale navigation into the laboratory and into the MRI scanning environment. Empirical studies to date identify navigation as an aspect of cognition that is vulnerable to the aging process. Functional and structural neuroimaging studies in humans suggest that age-related changes in the brain’s “navigation circuit” may underlie these behavioral age differences. Older adults also adopt unique spatial strategies and knowledge of these strategy preferences could enlighten both basic science research in spatial cognition and also inform the development of age-specific technological assistance that may extend functional independence of older adults into later life.

scholarly journals ANGER, LOVE, SADNESS: DO EMOTION WORDS HAVE THE SAME SEMANTIC MEANING ACROSS AGE-GROUPS?

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S841-S842
Author(s):  
Madeline J Nichols ◽  
Jennifer A Bellingtier ◽  
Frances Buttelmann
Keyword(s):  
Older Adults ◽  
Age Differences ◽  
Language Use ◽  
Age Groups ◽  
Past Research ◽  
Semantic Meaning ◽  
Younger Adults ◽  
Emotion Words ◽  
Emotion Word ◽  
Age Related

Abstract Every day we use emotion words to describe our experiences, but past research finds that the meanings of these words can vary. Furthermore, historical shifts in language use and experiential knowledge of the emotions may contribute to age-differences in what these emotion words convey. We examined age-related differences in the valence, arousal, and expression connoted by the words anger, love, and sadness. We predicted age-related differences in the semantic meanings of the words would emerge such that older adults would more clearly differentiate the positivity/negativity of the words, whereas younger adults would report higher endorsement for the conveyed arousal and expression. Participants included American and German older adults (N=61; mean age=68.98) and younger adults (N=77; mean age=20.77). Using the GRID instrument (Swiss Center for Affective Sciences, 2013), they rated each emotion word for its valence, arousal, and expression when used by a speaker of the participant’s native language. Across emotions and dimensions, older adults were generally more moderate in their understanding of emotion words. For example, German older adults rated anger and sadness as suggesting the speaker felt less bad and more good than the younger adults. American older adults rated love as connoting the speaker felt more bad and less good than younger adults. Arousal ratings were higher for German younger, as opposed to older, adults. Cultural differences were most pronounced for sadness such that German participants gave more moderate answers than American participants. Overall, our research suggests that there are age-related differences in the understanding of emotion words.

scholarly journals Neural pattern similarity differentially affects memory performance of younger and older adults: Age differences in neural similarity and memory

2019 ◽  
Author(s):  
Verena R. Sommer ◽  
Yana Fandakova ◽  
Thomas H. Grandy ◽  
Yee Lee Shing ◽  
Markus Werkle-Bergner ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Memory Performance ◽  
Activity Patterns ◽  
Quality Of Information ◽  
Neural Representations ◽  
Age Related ◽  
Pattern Similarity ◽  
The Brain

AbstractAge-related memory decline is associated with changes in neural functioning but little is known about how aging affects the quality of information representation in the brain. Whereas a long-standing hypothesis of the aging literature links cognitive impairments to less distinct neural representations in old age, memory studies have shown that high similarity between activity patterns benefits memory performance for the respective stimuli. Here, we addressed this apparent conflict by investigating between-item representational similarity in 50 younger (19–27 years old) and 63 older (63–75 years old) human adults (male and female) who studied scene-word associations using a mnemonic imagery strategy while electroencephalography was recorded. We compared the similarity of spatiotemporal frequency patterns elicited during encoding of items with different subsequent memory fate. Compared to younger adults, older adults’ memory representations were more similar to each other but items that elicited the most similar activity patterns early in the encoding trial were those that were best remembered by older adults. In contrast, young adults’ memory performance benefited from decreased similarity between earlier and later periods in the encoding trials, which might reflect their better success in forming unique memorable mental images of the joint picture–word pair. Our results advance the understanding of the representational properties that give rise to memory quality as well as how these properties change in the course of aging.Significance statementDeclining memory abilities are one of the most evident limitations for humans when growing older. Despite recent advances of our understanding of how the brain represents and stores information in distributed activation patterns, little is known about how the quality of information representation changes during aging and thus affects memory performance. We investigated how the similarity between neural representations relates to subsequent memory quality in younger and older adults. We present novel evidence that the interaction of pattern similarity and memory performance differs between age groups: Older adults benefited from increased similarity during early encoding whereas young adults benefited from decreased similarity between early and later encoding. These results provide insights into the nature of memory and age-related memory deficits.

scholarly journals Behavioral and fMRI evidence that arousal enhances bottom-up attention and memory selectivity in young but not older adults

2021 ◽  
Author(s):  
Sara N Gallant ◽  
Briana L Kennedy ◽  
Shelby L Bachman ◽  
Ringo Huang ◽  
Tae-Ho Lee ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Age Differences ◽  
Emotional Experience ◽  
Noradrenergic System ◽  
Attention And Memory ◽  
Bottom Up ◽  
Age Related ◽  
Selective Processing ◽  
The Brain

During a challenge or emotional experience, increases in arousal help us focus on the most salient or relevant details and ignore distracting stimuli. The noradrenergic system integrates signals about arousal states throughout the brain and helps coordinate this adaptive attentional selectivity. However, age-related changes in the noradrenergic system and attention networks in the brain may reduce the efficiency of arousal to modulate selective processing in older adults. In the current neuroimaging study, we examined age differences in how arousal affects bottom-up attention to category-selective stimuli differing in perceptual salience. We found a dissociation in how arousal modulates selective processing in the young and older brain. In young adults, emotionally arousing sounds enhanced selective incidental memory and brain activity in the extrastriate body area for salient versus non-salient images of bodies. Older adults showed no such advantage in selective processing under arousal. These age differences could not be attributed to changes in the arousal response or less neural distinctiveness in old age. Rather, our results suggest that, relative to young adults, older adults become less effective at focusing on salient over non-salient details during increases in emotional arousal.

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.

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