The Recordability of Two Sonomotor Responses in Young Normal Subjects

Background: It has been reported that up to 40% of patients over age 60 fail to generate a vestibular evoked myogenic potential (VEMP; Su et al, 2004). When this occurs it is difficult to determine whether the absent VEMP represents evidence of bilateral impairment of the vestibulocollic reflex pathway or a normal age-related variant (i.e., idiopathic absence). Purpose: The purpose of the present investigation was to determine whether both VEMPs and PAMs could be recorded reliably in a sample of neurologically and otologically intact young adults. If both could be obtained with high reliability in normal subjects, then the bilateral presence of PAM in the bilateral absence of VEMP, at least in younger patients, could be used to support the contention that the absent VEMP represented evidence of bilateral impairment. Research Design: A descriptive study. Study Sample: Attempts were made to record both the VEMP and a second sonomotor response, the postauricular muscle potential (PAM) from 20 young adults. Results: Results showed both the VEMP and the PAM were present in 90% of the ears. Both the VEMP and PAM responses were bilaterally absent for one subject. Also, the VEMP and PAM were unilaterally absent for two subjects. Subjects who generated VEMPs also generated a PAM in at least one ear. Conclusions: The present investigation represents an initial step in the determination of whether the presence of PAMs in the absence of VEMPs can be used as a method of validating the presence of an impairment affecting the vestibulocollic reflex pathway.

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Age-Related Differences in Arm and Trunk Responses to First and Repeated Exposure to Laterally Induced Imbalances

Brain Sciences ◽

10.3390/brainsci10090574 ◽

2020 ◽

Vol 10 (9) ◽

pp. 574

Author(s):

Ruth Y. Akinlosotu ◽

Nesreen Alissa ◽

John D. Sorkin ◽

George F. Wittenberg ◽

Kelly P. Westlake

Keyword(s):

Older Adults ◽

Young Adults ◽

Initial Step ◽

Neck Muscle ◽

Balance Recovery ◽

Balance Confidence ◽

Positive Effects ◽

Age Related ◽

Lift Off ◽

Step Type

The objective of this study was to examine age-related differences in arm and trunk responses during first and repeated step induced balance perturbations. Young and older adults received 10 trials of unpredictable lateral platform translations. Outcomes included maximum arm and trunk displacement within 1 s of perturbation and at first foot lift off (FFLO), arm and neck muscle activity as recorded using electromyography (EMG), initial step type, balance confidence, and percentage of harness-assisted trials. Compared to young adults, older adults demonstrated greater arm and trunk angular displacements during the first trial, which were present at FFLO and negatively associated with balance confidence. Unlike young adults, recovery steps in older adults were directed towards the fall with a narrowed base of support. Over repeated trials, rapid habituation of first-trial responses of bilateral arm and trunk displacement and EMG amplitude was demonstrated in young adults, but was absent or limited in older adults. Older adults also relied more on harness assistance during balance recovery. Exaggerated arm and trunk responses to sudden lateral balance perturbations in older adults appear to influence step type and balance recovery. Associations of these persistently amplified movements with an increased reliance on harness assistance suggest that training to reduce these deficits could have positive effects in older adults with and without neurological disorders.

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Inefficient Encoding as an Explanation for Age-Related Deficits in Recollection-Based Processing

Journal of Psychophysiology ◽

10.1027/0269-8803/a000122 ◽

2014 ◽

Vol 28 (3) ◽

pp. 148-161 ◽

Cited By ~ 12

Author(s):

David Friedman ◽

Ray Johnson

Keyword(s):

Older Adults ◽

Young Adults ◽

Cognitive Processes ◽

Brain Activity ◽

Memory Performance ◽

Brain Regions ◽

Semantic Retrieval ◽

Age Related ◽

The Face ◽

Episodic Memories

A cardinal feature of aging is a decline in episodic memory (EM). Nevertheless, there is evidence that some older adults may be able to “compensate” for failures in recollection-based processing by recruiting brain regions and cognitive processes not normally recruited by the young. We review the evidence suggesting that age-related declines in EM performance and recollection-related brain activity (left-parietal EM effect; LPEM) are due to altered processing at encoding. We describe results from our laboratory on differences in encoding- and retrieval-related activity between young and older adults. We then show that, relative to the young, in older adults brain activity at encoding is reduced over a brain region believed to be crucial for successful semantic elaboration in a 400–1,400-ms interval (left inferior prefrontal cortex, LIPFC; Johnson, Nessler, & Friedman, 2013 ; Nessler, Friedman, Johnson, & Bersick, 2007 ; Nessler, Johnson, Bersick, & Friedman, 2006 ). This reduced brain activity is associated with diminished subsequent recognition-memory performance and the LPEM at retrieval. We provide evidence for this premise by demonstrating that disrupting encoding-related processes during this 400–1,400-ms interval in young adults affords causal support for the hypothesis that the reduction over LIPFC during encoding produces the hallmarks of an age-related EM deficit: normal semantic retrieval at encoding, reduced subsequent episodic recognition accuracy, free recall, and the LPEM. Finally, we show that the reduced LPEM in young adults is associated with “additional” brain activity over similar brain areas as those activated when older adults show deficient retrieval. Hence, rather than supporting the compensation hypothesis, these data are more consistent with the scaffolding hypothesis, in which the recruitment of additional cognitive processes is an adaptive response across the life span in the face of momentary increases in task demand due to poorly-encoded episodic memories.

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How adolescents and adults translate motivational value to action: Age-related shifts in strategic physical effort exertion for monetary rewards

10.31234/osf.io/zcw4s ◽

2019 ◽

Author(s):

Alexandra M Rodman ◽

Katherine Powers ◽

Catherine Insel ◽

Erik K Kastman ◽

Katherine Kabotyanski ◽

...

Keyword(s):

Young Adults ◽

Early Adulthood ◽

Theoretical Models ◽

Incentive Motivation ◽

Reward Processing ◽

Monetary Reward ◽

Physical Effort ◽

Monetary Rewards ◽

Age Related ◽

Adolescents And Adults

Adults titrate the degree of physical effort they are willing to expend according to the magnitude of reward they expect to obtain, a process guided by incentive motivation. However, it remains unclear whether adolescents, who are undergoing normative developmental changes in cognitive and reward processing, translate incentive motivation into action in a way that is similarly tuned to reward value and economical in effort utilization. The present study adapted a classic physical effort paradigm to quantify age-related changes in motivation-based and strategic markers of effort exertion for monetary rewards from adolescence to early adulthood. One hundred and three participants aged 12-23 years completed a task that involved exerting low or high amounts of physical effort, in the form of a hand grip, to earn low or high amounts of money. Adolescents and young adults exhibited highly similar incentive-modulated effort for reward according to measures of peak grip force and speed, suggesting that motivation for monetary reward is consistent across age. However, young adults expended energy more economically and strategically: whereas adolescents were prone to exert excess physical effort beyond what was required to earn reward, young adults were more likely to strategically prepare before each grip phase and conserve energy by opting out of low reward trials. This work extends theoretical models of development of incentive-driven behavior by demonstrating that layered on similarity in motivational value for monetary reward, there are important differences in the way behavior is flexibly adjusted in the presence of reward from adolescence to young adulthood.

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Inflamm-Aging Is Associated with Lower Plasma PTX3 Concentrations and an Impaired Capacity of PBMCs to Express hTERT following LPS Stimulation

Mediators of Inflammation ◽

10.1155/2019/2324193 ◽

2019 ◽

Vol 2019 ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

Aaron L. Slusher ◽

Tiffany M. Zúñiga ◽

Edmund O. Acevedo

Keyword(s):

Gene Expression ◽

Young Adults ◽

Telomere Length ◽

Immune Cell ◽

Ex Vivo ◽

Middle Aged ◽

Human Telomerase Reverse Transcriptase ◽

Negatively Associated ◽

Htert Gene ◽

Age Related

Age-related elevations in proinflammatory cytokines, known as inflamm-aging, are associated with shorter immune cell telomere lengths. Purpose. This study examined the relationship of plasma PTX3 concentrations, a biomarker of appropriate immune function, with telomere length in 15 middle-aged (40-64 years) and 15 young adults (20-31 years). In addition, PBMCs were isolated from middle-aged and young adults to examine their capacity to express a key mechanistic component of telomere length maintenance, human telomerase reverse transcriptase (hTERT), following ex vivo cellular stimulation. Methods. Plasma PTX3 and inflammatory cytokines (i.e., IL-6, IL-10, TGF-β, and TNF-α), PBMC telomere lengths, and PBMC hTERT gene expression and inflammatory protein secretion following exposure to LPS, PTX3, and PTX3+LPS were measured. Results. Aging was accompanied by the accumulation of centrally located visceral adipose tissue, without changes in body weight and BMI, and alterations in the systemic inflammatory milieu (decreased plasma PTX3 and TGF-β; increased TNF-α (p≤0.050)). In addition, shorter telomere lengths in middle-aged compared to young adults (p=0.011) were negatively associated with age, body fat percentages, and plasma TNF-α (r=−0.404, p=0.027; r=−0.427, p=0.019; and r=−0.323, p=0.041, respectively). Finally, the capacity of PBMCs to increase hTERT gene expression following ex vivo stimulation was impaired in middle-aged compared to young adults (p=0.033) and negatively associated with telomere lengths (r=0.353, p=0.028). Conclusions. Proinflammation and the impaired hTERT gene expression capacity of PBMCs may contribute to age-related telomere attrition and disease.

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Age-related differences in monocyte DNA methylation and immune function in healthy Kenyan adults and children

Immunity & Ageing ◽

10.1186/s12979-021-00223-2 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Katherine R. Dobbs ◽

Paula Embury ◽

Emmily Koech ◽

Sidney Ogolla ◽

Stephen Munga ◽

...

Keyword(s):

Gene Expression ◽

Dna Methylation ◽

Young Adults ◽

Expression Profiles ◽

Gene Expression Profiles ◽

Innate Immune ◽

Inflammatory Gene Expression ◽

Cpg Sites ◽

Age Related ◽

Adults And Children

Abstract Background Age-related changes in adaptive and innate immune cells have been associated with a decline in effective immunity and chronic, low-grade inflammation. Epigenetic, transcriptional, and functional changes in monocytes occur with aging, though most studies to date have focused on differences between young adults and the elderly in populations with European ancestry; few data exist regarding changes that occur in circulating monocytes during the first few decades of life or in African populations. We analyzed DNA methylation profiles, cytokine production, and inflammatory gene expression profiles in monocytes from young adults and children from western Kenya. Results We identified several hypo- and hyper-methylated CpG sites in monocytes from Kenyan young adults vs. children that replicated findings in the current literature of differential DNA methylation in monocytes from elderly persons vs. young adults across diverse populations. Differentially methylated CpG sites were also noted in gene regions important to inflammation and innate immune responses. Monocytes from Kenyan young adults vs. children displayed increased production of IL-8, IL-10, and IL-12p70 in response to TLR4 and TLR2/1 stimulation as well as distinct inflammatory gene expression profiles. Conclusions These findings complement previous reports of age-related methylation changes in isolated monocytes and provide novel insights into the role of age-associated changes in innate immune functions.

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Quantifying the effects of electrode placement and montage on measures of cVEMP amplitude and muscle contraction

Journal of Vestibular Research ◽

10.3233/ves-200033 ◽

2020 ◽

pp. 1-13

Author(s):

Sendhil Govender ◽

Sally M. Rosengren

Keyword(s):

Muscle Contraction ◽

Normal Subjects ◽

Electrode Placement ◽

Electrode Position ◽

Test Results ◽

Vestibular Evoked Myogenic Potential ◽

Active Electrode ◽

Myogenic Potential ◽

Position Errors ◽

Test Outcomes

BACKGROUND: The cervical vestibular evoked myogenic potential (cVEMP) can be affected by the recording parameters used to quantify the response. OBJECTIVE: We investigated the effects of electrode placement and montage on the variability and symmetry of sternocleidomastoid (SCM) contraction strength and cVEMP amplitude. METHODS: We used inter-side asymmetries in electrode placement to mimic small clinical errors in twenty normal subjects. cVEMPs were recorded at three active electrode sites and referred to the distal SCM tendon (referential montages: upper, conventional and lower). Additional bipolar montages were constructed offline to measure SCM contraction strength using closely-spaced electrode pairs (bipolar montages: superior, lower and outer). RESULTS: The conventional montage generally produced the largest cVEMP amplitudes (P < 0.001). SCM contraction strength was larger for referential montages than bipolar ones (P < 0.001). Inter-side electrode position errors produced large variations in cVEMP and SCM contraction strength asymmetries in some subjects, producing erroneous abnormal test results. CONCLUSION: Recording locations affect cVEMP amplitude and SCM contraction strength. In most cases, small changes in electrode position had only minor effects but, in a minority of subjects, the different montages produced large changes in cVEMP and contraction amplitudes and asymmetry, potentially affecting test outcomes.

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Asymmetry in Event-Related Potentials to Simulated Auditory Motion in Children, Young Adults, and Seniors

Journal of the American Academy of Audiology ◽

10.1055/s-0040-1715943 ◽

2002 ◽

Vol 13 (01) ◽

pp. 001-013 ◽

Cited By ~ 2

Author(s):

James Jerger ◽

Rebecca Estes

Keyword(s):

Young Adults ◽

Right Hemisphere ◽

Apparent Movement ◽

Event Related Potentials ◽

Auditory Evoked Responses ◽

Age Related ◽

Related Potentials ◽

Velocity Information ◽

The Right ◽

Age Range

We studied auditory evoked responses to the apparent movement of a burst of noise in the horizontal plane. Event-related potentials (ERPs) were measured in three groups of participants: children in the age range from 9 to 12 years, young adults in the age range from 18 to 34 years, and seniors in the age range from 65 to 80 years. The topographic distribution of grand-averaged ERP activity was substantially greater over the right hemisphere in children and seniors but slightly greater over the left hemisphere in young adults. This finding may be related to age-related differences in the extent to which judgments of sound movement are based on displacement versus velocity information.

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