HIPPOCAMPAL GLUTAMATE MODULATION DURING MEMORY ENCODING: ASSOCIATION WITH AGE AND SUBFIELD VOLUMES

Abstract Hippocampal glutamatergic activity plays a pivotal role in memory consolidation, including the ability to form novel associations that declines with age. To test whether glutamatergic dysfunction may underpin age-related memory declines, we examined in vivo age differences in hippocampal glutamate modulation during encoding of associations, and its relationship with hippocampal subfield volumes. Proton functional magnetic resonance spectroscopy was performed on 32 young (25.1±2.8 years; 18 females) and 16 older (65.9±2.7 years; 7 females) adults to measure changes in hippocampal (randomly assigned right or left) glutamate during an object-location paired association learning task (with 12 cycles of encoding-retrieval epochs). Volumes of the dentate gyrus&CA3, CA1, subiculum, and entorhinal cortex were manually measured from T2-weighted MRI images. Memory performance differed between the age-groups [F(1, 46)=8.56, p<.01], with the older attaining a lower asymptote [t(46)=2.93, p<.05] compared to the younger. Age differences in glutamate were observed only during encoding (age-group x epoch: F(3,137)=5.28, p<.01), and varied over the epochs. Young adults showed increased glutamate during the first four encoding epochs of each cycle, with levels remaining high thereafter. Old adults evidenced a decrease in glutamate during the first four epochs, and a slow, sustained ramping-up afterwards. Including both age-groups, the maximum change in glutamate, calculated using the maximum and minimum levels during encoding, was positively associated with CA1 [F(2,39)=4.28, p<.05] and the dentate gyrus&CA3 volume [F(2,39)=4.4, p<.05], after correcting for multiple comparisons. Glutamate modulation specific to encoding may underlie age-related memory declines and be related to selected hippocampal subfield volumes.

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Adult age differences in the effects of processing on storage in working memory: A meta-analysis

10.31234/osf.io/x2uk7 ◽

2018 ◽

Author(s):

Agnieszka J Jaroslawska ◽

Stephen Rhodes

Keyword(s):

Older Adults ◽

Working Memory ◽

Age Differences ◽

Memory Performance ◽

Meta Analysis ◽

Age Groups ◽

Effect Sizes ◽

Future Research ◽

Adult Age ◽

Age Related

Normal adult aging is known to be associated with lower performance on tasks assessing the short-term storage of information. However, whether or not there are additional age-related deficits associated with concurrent storage and processing demands within working memory remains unclear. Methodological differences across studies are considered critical factors responsible for the variability in the magnitude of the reported age effects. Here we synthesized comparisons of younger and older adults' performance on tasks measuring storage alone against those combining storage with concurrent processing of information. We also considered the influence of task-related moderator variables. Meta-analysis of effect sizes revealed a small but disproportionate effect of processing on older adults' memory performance. Moderator analysis indicated that equating single task storage performance across age groups (titration) and the nature of the stimulus material were important determinants of memory accuracy. Titration of storage task difficulty was found to lead to smaller, and non-significant, age-differences in dual task costs. These results were corroborated by supplementary Brinley and state-trace analyses. We discuss these findings in relation to the extant literature and current working memory theory as well as possibilities for future research to address the residual heterogeneity in effect sizes.

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Five reasons COVID-19 is less severe in younger age groups

Evolution Medicine and Public Health ◽

10.1093/emph/eoaa050 ◽

2020 ◽

Author(s):

Paul W Turke

Keyword(s):

Life History ◽

Life History Theory ◽

Age Of Onset ◽

Age Groups ◽

Medical Community ◽

System Function ◽

The Third ◽

Immune System Function ◽

Age Related ◽

Younger Age

Abstract The severity of COVID-19 is age-related, with the advantage going to younger age groups. Five reasons are presented. The first two are well-known, are being actively researched by the broader medical community, and therefore are discussed only briefly here. The third, fourth, and fifth reasons derive from evolutionary life history theory, and potentially fill gaps in current understanding of why and how young and old age groups respond differently to infection with SARS-CoV-2. Age of onset of generalized somatic aging, and the timing of its progression, are identified as important causes of these disparities, as are specific antagonistic pleiotropic tradeoffs in immune system function.

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FosGFP expression does not capture a sensory learning-related engram in superficial layers of mouse barrel cortex

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2112212118 ◽

2021 ◽

Vol 118 (52) ◽

pp. e2112212118

Author(s):

Jiseok Lee ◽

Joanna Urban-Ciecko ◽

Eunsol Park ◽

Mo Zhu ◽

Stephanie E. Myal ◽

...

Keyword(s):

Pyramidal Neurons ◽

Barrel Cortex ◽

Sensory Information ◽

Learning Task ◽

Early Gene ◽

Sensory Stimuli ◽

Association Learning ◽

Neural Ensembles ◽

Dependent Learning

Immediate-early gene (IEG) expression has been used to identify small neural ensembles linked to a particular experience, based on the principle that a selective subset of activated neurons will encode specific memories or behavioral responses. The majority of these studies have focused on “engrams” in higher-order brain areas where more abstract or convergent sensory information is represented, such as the hippocampus, prefrontal cortex, or amygdala. In primary sensory cortex, IEG expression can label neurons that are responsive to specific sensory stimuli, but experience-dependent shaping of neural ensembles marked by IEG expression has not been demonstrated. Here, we use a fosGFP transgenic mouse to longitudinally monitor in vivo expression of the activity-dependent gene c-fos in superficial layers (L2/3) of primary somatosensory cortex (S1) during a whisker-dependent learning task. We find that sensory association training does not detectably alter fosGFP expression in L2/3 neurons. Although training broadly enhances thalamocortical synaptic strength in pyramidal neurons, we find that synapses onto fosGFP+ neurons are not selectively increased by training; rather, synaptic strengthening is concentrated in fosGFP− neurons. Taken together, these data indicate that expression of the IEG reporter fosGFP does not facilitate identification of a learning-specific engram in L2/3 in barrel cortex during whisker-dependent sensory association learning.

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Age affects pigeon memory capacity, but not representation of serial order, during a locomotor sequential-learning task

10.21203/rs.3.rs-289410/v1 ◽

2021 ◽

Author(s):

Christina Meier ◽

Parisa Sepehri ◽

Debbie M. Kelly

Keyword(s):

Cognitive Processing ◽

Age Groups ◽

Serial Order ◽

Memory Capacity ◽

Learning Task ◽

Individual Variability ◽

Sequential Learning ◽

Choice Test ◽

Age Related ◽

Recall Memory

Abstract Aging affects individuals of every species, with sometimes detrimental effects on memory and cognition. The simultaneous-chaining task, a sequential-learning task, requires subjects to select items in a predetermined sequence, putting demands on memory and cognitive processing capacity. It is thus a useful tool to investigate age-related differences in these domains. Pigeons of three age groups (young, adult and aged) completed a locomotor adaptation of the task, learning a list of four items. Training began presenting only the first item; additional items were added, one at a time, once previous items were reliably selected in their correct order. Although memory capacity declined noticeably with age, not all aged pigeons showed impairments compared to younger pigeons, suggesting that inter-individual variability emerged with age. During a subsequent free-recall memory test, when all trained items were presented alongside novel distractor items, most pigeons did not reproduce the trained sequence in the absence of reinforcement. During a further forced-choice test, when pigeons were given a choice between only two of the trained items, all three age groups showed evidence of an understanding of the ordinal relationship between items by choosing the earlier item, indicating that complex cognitive processing, unlike memory capacity, remained unaffected by age.

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Internal, external and repeated-sprint demands in small-sided games: A comparison between bouts and age groups in elite youth soccer players

PLoS ONE ◽

10.1371/journal.pone.0249906 ◽

2021 ◽

Vol 16 (4) ◽

pp. e0249906

Author(s):

Richard Hauer ◽

Paul Störchle ◽

Bettina Karsten ◽

Harald Tschan ◽

Arnold Baca

Keyword(s):

Age Groups ◽

Soccer Players ◽

Internal Load ◽

Youth Soccer ◽

Training Tool ◽

Low Intensity ◽

Repeated Sprint ◽

Age Related ◽

Younger Age ◽

Image Position

This study investigated the activity profile during small-sided games (SSG) in elite youth soccer players. Internal load (IL) including heart rate (HR) and external load (EL) such as distance covered in different speed-zones (SZ) were collected from forty-eight players of three different teams (U15, U16, U18). The investigation included a total of eighteen 5vs.5 SSGs, each consisting of four 2-minute bouts on a 40x32m pitch during spring season. Total group results (n = 48) showed a reduction in total-distance (p = 0.001; ηp2 = 0.12), high-intensity-running (p = 0.009; ηp2 = 0.09), and low-intensity-running distance (p = 0.028; ηp2 = 0.07) between bouts. Similarly, a reduction in the number of both acceleration-low (p = 0.001; ηp2 = 0.12) and deceleration-high (p = 0.003; ηp2 = 0.11) values was observed. Additionally, time spent in HR-zones 3 and 4 (p≤0.007; ηp2 ≥ 0.10), increased, with a reduction in HR-zone 1 (p = 0.000, ηp2 = 0.25). Age group comparison showed less distance covered in SZ 1 (p≤0.000; ηp2 = 0.56) and greater deceleration-high values (p≤0.038; ηp2 = 0.32) in U15 players compared to other age groups. Further, U15 showed lower values in low-intensity-running compared to U18 (p = 0.038; ηp2 = 0.22). No age-related differences were found for IL and repeated sprint ability (RSA) values. The higher EL in younger age groups should be taken into account when implementing soccer specific SSGs. In addition, HRmean values between 80–85% of HRmax and RSA numbers, which are similar to match-play data, indicate SSGs as an effective training tool to prepare youth soccer athletes for the demands of competition.

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

Journal of Applied Biomechanics ◽

10.1123/jab.2013-0275 ◽

2014 ◽

Vol 30 (4) ◽

pp. 542-546 ◽

Cited By ~ 7

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.

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Longitudinal force and stress of rat's esophagus: age-related changes.

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1977.232.6.e580 ◽

1977 ◽

Vol 232 (6) ◽

pp. E580

Author(s):

M P Zabinski ◽

P Biancani

Keyword(s):

Age Groups ◽

Longitudinal Direction ◽

Longitudinal Force ◽

Active Stress ◽

Length Relationship ◽

Age Related ◽

Old Rats ◽

The Difference

Longitudinal force-length relationship of the rat esophagus was studied in vitro in three age groups: 1 mo, 3 mo, and 12 mo. The length of maximum force development (MFD) occurs at 1.4-1.5 times the in vivo length for all age groups. The active force developed at MFD increases markedly with age. The difference in the active forces in the 3-mo and 12-mo age groups is due to differences in cross section because the active stress of the esophagus in the longitudinal direction is approximately equal for the two age groups. The active stress in the 1-mo-old rats is lower than in the 3-mo-old rats, suggesting an increased contractility of the esophagus with age in this period of development.

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Growth-related changes in the influence of nitric oxide on arteriolar tone

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1999.277.4.h1570 ◽

1999 ◽

Vol 277 (4) ◽

pp. H1570-H1578 ◽

Cited By ~ 8

Author(s):

J. R. Linderman ◽

M. A. Boegehold

Keyword(s):

Nitric Oxide ◽

Age Groups ◽

Prostaglandin E ◽

Similar Amount ◽

Juvenile Growth ◽

Juvenile Rats ◽

Age Related ◽

Weanling Rats ◽

Arteriolar Tone

This study was designed to determine whether juvenile growth is accompanied by changes in the local influence of nitric oxide (NO) or prostaglandins on arteriolar tone. In vivo microscopy was used to study proximal arterioles in the spinotrapezius muscle of rats 4–5 wk (weanling), 7–8 wk (juvenile), and 11–12 wk (mature) of age. From 4 to 12 wk of age, arterioles underwent an increase in resting diameter (from 31 ± 2 to 49 ± 2 μm) and volume flow (from 7 ± 1 to 10 ± 1 nl/s) but a decrease in resting wall shear rate (from 1,901 ± 150 to 748 ± 50 s−1). NO synthase inhibition with N G-monomethyl-l-arginine (l-NMMA) had no effect on arteriolar diameters in weanling rats but reduced diameters by 14 ± 4% in juvenile rats and by 13 ± 4% in mature rats. Cyclooxygenase inhibition with meclofenamate reduced arteriolar diameters by a similar amount (13 ± 4 to 18 ± 3%) in all age groups. There were no age-related differences in arteriolar responsiveness to locally applied sodium nitroprusside or prostaglandin E2. Arteriolar responsiveness to ACh was also similar in all groups, but thel-NMMA-sensitive portion of this response was smaller in mature rats than in weanling rats. Elevation of flow-related shear stress caused arteriolar dilation in juvenile rats but not in weanling rats. These findings suggest that arteriolar smooth muscle responsiveness to NO or prostaglandins does not change during juvenile growth and that basally released vasodilator prostaglandins exert a constant influence on arteriolar tone throughout this period. Basal NO activity also modulates arteriolar tone in juvenile and mature rats but not in weanling rats. In contrast, agonist-stimulated NO release is prominent in weanling and juvenile rats but somewhat decreased in mature rats, where cyclooxygenase products also contribute to ACh induced dilation.

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Vascular Risk Moderates Associations between Hippocampal Subfield Volumes and Memory

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00435 ◽

2013 ◽

Vol 25 (11) ◽

pp. 1851-1862 ◽

Cited By ~ 36

Author(s):

Andrew R. Bender ◽

Ana M. Daugherty ◽

Naftali Raz

Keyword(s):

Dentate Gyrus ◽

Memory Performance ◽

Complex Structure ◽

Vascular Risk Factor ◽

Advanced Age ◽

Vascular Risk ◽

Measurement Occasion ◽

Age Related ◽

Path Models ◽

Using Data

Advanced age and vascular risk negatively affect episodic memory. The hippocampus (HC) is a complex structure, and little is known about the roles of different HC regions in age-related memory declines. Using data from an ongoing longitudinal study, we investigated whether memory functions are related to volumes of specific HC subregions (CA1-2, CA3-4/dentate gyrus, and subiculum). Furthermore, we inquired if arterial hypertension, a common age-related vascular risk factor, modifies age-related differences in HC regional volumes, concurrent memory performance, and improvement in memory over multiple administrations. Healthy adults (n = 49, 52–82 years old) completed associative recognition and free recall tasks. In grouped path models, covariance structures differed between hypertensive and normotensive participants. Whereas larger CA3-4/dentate gyrus volumes predicted greater improvement in associative memory over repeated tests regardless of vascular risk, CA1-2 volumes were associated with improvement in noun recall only in hypertensive participants. Only among hypertensive participants, CA1-2 volumes negatively related to age and CA3-4/dentate gyrus and CA1-2 volumes were associated with performance at the last measurement occasion. These findings suggest that relatively small regions of the HC may play a role in age-related memory declines and that vascular risk factors associated with advanced age may modify that relationship.

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Reexamination of Accelerometer Calibration with Energy Expenditure as Criterion: VO2net Instead of MET for Age-Equivalent Physical Activity Intensity

Sensors ◽

10.3390/s19153377 ◽

2019 ◽

Vol 19 (15) ◽

pp. 3377 ◽

Cited By ~ 3

Author(s):

Daniel Arvidsson ◽

Jonatan Fridolfsson ◽

Christoph Buck ◽

Örjan Ekblom ◽

Elin Ekblom-Bak ◽

...

Keyword(s):

Physical Activity ◽

Age Groups ◽

Accelerometer Data ◽

Physical Activity Intensity ◽

Free Living ◽

Activity Intensity ◽

Age Related ◽

Younger Age ◽

Metabolic Equivalent Of Task ◽

Adolescents And Adults

Accelerometer calibration for physical activity (PA) intensity is commonly performed using Metabolic Equivalent of Task (MET) as criterion. However, MET is not an age-equivalent measure of PA intensity, which limits the use of MET-calibrated accelerometers for age-related PA investigations. We investigated calibration using VO2net (VO2gross − VO2stand; mL⋅min−1⋅kg−1) as criterion compared to MET (VO2gross/VO2rest) and the effect on assessment of free-living PA in children, adolescents and adults. Oxygen consumption and hip/thigh accelerometer data were collected during rest, stand and treadmill walk and run. Equivalent speed (Speedeq) was used as indicator of the absolute speed (Speedabs) performed with the same effort in individuals of different body size/age. The results showed that VO2net was higher in younger age-groups for Speedabs, but was similar in the three age-groups for Speedeq. MET was lower in younger age-groups for both Speedabs and Speedeq. The same VO2net-values respective MET-values were applied to all age-groups to develop accelerometer PA intensity cut-points. Free-living moderate-and-vigorous PA was 216, 115, 74 and 71 min/d in children, adolescents, younger and older adults with VO2net-calibration, but 140, 83, 74 and 41 min/d with MET-calibration, respectively. In conclusion, VO2net calibration of accelerometers may provide age-equivalent measures of PA intensity/effort for more accurate age-related investigations of PA in epidemiological research.

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