Meaningful semantic context has been shown to improve comprehension of spoken sentences by young and old adults, especially in difficult listening conditions. Whether older adults benefit differently than younger adults is a topic of some controversy. I asked young (14 participants, 18-25) and older adults (20 participants, 60-75) to report entire sentences which contained either a coherent or anomalous global semantic context (e.g. coherent: “Her new skirt was made of denim”, anomalous: “Her good slope was done in carrot”). Sentences were mixed with signal-correlated noise, at 10 signal-to-noise ratios (-6 to +2 dB and clear speech). Percentage scores were converted to rationalized arcsine units and subjected to a repeated-measures ANOVA; slopes from psychometric functions fitted to the transformed data were also analyzed. Cognitive and hearing threshold differences were considered as factors influencing results. Finally, individual variability in the use of context was explored. Comprehension by both groups benefited from meaningful context, without a clear difference in the overall amount of benefit obtained. Cognitive factors did not appear to influence the results, although differences in hearing thresholds likely contributed to the consistent performance decrement for older adults. Individuals varied greatly in their use of context, a possible explanation for inconsistent results in studies comparing context use by young and older people. fMRI was then used to look at neural activity associated with deriving benefit from meaningful context. Whole-brain EPI data were acquired from young (16 participants, 19-26) adults using a sparse imaging design. Participants heard coherent and anomalous sentences in the scanner, and were asked to report what they heard on half of the trials. Individual’s word-report data obtained in the scanner were used to model intelligibility in the analysis and results were compared to an analysis conducted using intelligibility estimates based on group data from another study. In addition to bilateral temporal activity associated with increasing intelligibility, I observe a large left inferior-frontal region in which BOLD signal correlated more strongly with highly intelligible anomalous compared to highly intelligible coherent prose, presumably reflecting challenged semantic integration and supporting Hagoort’s (2005) model of semantic unification. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2008-09-18 23:01:40.979

Purpose: An open mouth approach is used in voice therapy for enhancing speech and voice production and relaxing the laryngeal musculature. The acoustic and physiological consequences of an open jaw posture, however, have not been clearly understood due to a paucity of cross-system studies taking the age effect into consideration. The major aims of this study are twofold (1) to examine if the geriatric voice may be improved using an “open jaw” posture and (2) if an aging effect on the voice of normal healthy adults can be detected through acoustic and physiological measures Method: The main part of this study involved simultaneous multi-channel voice recordings obtained from 85 healthy adults aged between 38 and 93 years. A convenience sampling strategy was used to recruit at least five females and five males in each of four age groups, 35-59 years (35+), 60-69 (60+), 70-79 (70+), and above 80 (80+). For simultaneous acoustic, electroglottographic (EGG), and jaw displacement recordings, participants were asked to perform two tasks which included a sustained vowel task and a sentence production task. The sustained vowel task involved sustaining the vowel /a/ in five different conditions, an isolated vowel /a/ produced at normal, low, and high pitch levels and the vowel /a/ initiated with a consonant (/m/ and /h/). The sentence production task involved production of the sentence 'We saw two cars,' containing the vowels /i, ɔ, u, a/. For simultaneous airflow-EGG recordings, participants were asked to sustain the vowel /a/ at normal pitch. For simultaneous airflow-air pressure-EGG recordings, participants were asked to repeat /pa/ five times in one breath. Participants were asked to perform all of the tasks using two jaw postures (normal and open). A series of univariate analysis of variances were used to identify instrumental measures sensitive for discriminating between the four age groups and the two jaw postures. A follow-up perceptual study was conducted to determine the effect of an open jaw posture on vowel intelligibility and voice clarity. A quota sampling strategy was used to recruit 40 normal hearing participants, including 20 females (age range = 18-42 years, mean = 25.3, SD = 7.9) and 20 males (age range = 18-47, mean = 23.6, SD = 6.7). These listeners were presented with vowels segmented from the sentences recorded in the first experiment and asked to perform a vowel identification and a voice clarity discrimination task. The vowel samples were taken from 40 speakers, with five females and five males in each of the four age groups (35+, 60+, 70+, and 80+). The percentages of correct vowel identification for voices produced with normal and open jaw postures were compared. The percentages of vowels judged as 'clearer' in a normal-open jaw contrast pairs were also calculated for comparison. Results: Significant age group effects were found in this study for both genders on fundamental frequency (F0), voice onset time (VOT) (/ka/), open quotient (OQ), and speed quotient (SQ), with additional age differences detected for females on %jitter, %shimmer, signal-to-noise ratio (SNR), and the second formant frequency (F2), and for males a significant age group effect was found on VOT (/tu/). Results for both females and males revealed significant open jaw posture effects on F0, F2, VOT (/ka/), MFR, SPL and vowel space area. In addition, for females significant posture effects were found on F1, subglottal pressure and the H1-H2 amplitude difference, and for males, significant posture effects were found on %jitter and VOT-/tu/. Results from the follow-up perceptual study revealed that an open jaw posture was associated with better vowel identification and better voice clarity. Conclusions: A selection of instrumental measures was shown to be useful for detecting voice changes due to aging. Instrumental and perceptual evidence was found that an open jaw posture was associated with positive changes in vocal behaviours, including improved phonatory stability, vocal power, and voice clarity.

Objective: The primary purpose of this study was to determine the influence of high frequency peripheral hearing loss on test performance on the University of Canterbury Adaptive Speech Test – Filtered Words (UCAST-FW). We also aimed to investigate (1) if there is an ear advantage in performing the UCAST-FW; (2) whether there is any correlation between the UCAST-FW score and age; (3) the effectiveness of a binaural practice run in reducing the learning effect; and (4) the average time required for older adults to complete the UCAST-FW. Method: A total of 18 participants with normal hearing (≤ 25 dB Hearing Level (HL) at octave intervals of 250 through 4000 Hz in both ears) and 19 participants with varying degrees of high frequency sensorineural hearing loss (>25 dB HL at frequencies above 1000 Hz) were included in this study. All participants were native New Zealand English speakers, aged between 55-71 years, with normal low frequency hearing (≤25 dB at 250, 500 and 1000 Hz), had speech scores consistent with their audiogram, normal cognition and judged by the examiner to be capable of completing test protocols in terms of sufficient eyesight, alertness and motor control. Participants underwent a full diagnostic hearing test, the Montreal Cognitive Assessment, the Dichotic Digits Test, the Random Gap Detection Test and the UCAST-FW. Results: Findings indicated that the presence of a high frequency peripheral hearing loss had no significant influence on the UCAST-FW score. Findings also showed no significant ear advantage, or any trend between the participant’s UCAST-FW score and their age. A binaural practice run comprised of 5 initial and 15 working reversals was effective in reducing any learning effect. The UCAST-FW took an average of 15 minutes to complete, and the results showed no correlation between the test completion time and the participant’s age. Conclusion: Findings suggested that the listener’s high frequency peripheral hearing sensitivity had no significant influence on their UCAST-FW score and thus the UCAST-FW can potentially be an effective test for assessing Auditory Processing Disorder (APD) in older adults and the elderly regardless of their high frequency peripheral hearing sensitivity. The development of test material in New Zealand English, as well as the investigation of the validity of the UCAST-FW in assessing APD in older adults and the influence of cognitive functioning on test performance is necessary before the UCAST-FW can be implemented in New Zealand clinical Audiology settings.

<p> Hearing loss and cognitive impairment are significant health problems, threatening the independent function of older adults. While there appears to be a strong relationship between the two conditions, the mechanisms underlying this association are complex and are not fully elucidated.</p><p> The purpose of this secondary analysis was to explore the relationship between hearing ability and cognitive performance in older adults. In addition, this study attempted to examine the role of depressive symptoms in the relationship between hearing loss and cognitive performance. Comprehensive measures of peripheral hearing, central auditory processing and cognitive performance were utilized to examine these relationships in a sample (N = 30) of adults aged 60 years and older. The Geriatric Depression Scale (GDS) was used to assess depressive symptoms.</p><p> Correlational analyses revealed a statistically significant relationship between central auditory processing and executive function. Statistically significant relationships were also observed between speed of processing and peripheral hearing as well as central auditory processing. No significant relationships were noted between depressive symptoms, hearing acuity and cognitive performance. While the correlation coefficients <i>(r)</i> for several of the hearing and cognitive performance measures were not statistically significant, medium effect sizes were detected, suggesting a moderate association may exist between these variables.</p>

L-glutamate is the predominant excitatory amino acid neurotransmitter inthe mammalian central nervous system. Prior aging studies have focusedprimarily on dopaminergic circuitry of the striatum, and data obtained studyingglutamate regulation in the striatum have been largely equivocal. Thesediscrepancies are due in large part to the limitations of microdialysis; while it isextremely sensitive to minute concentrations of analyte, it is lacking in terms ofthe temporal resolution necessary to study a neurotransmitter with rapid releaseand clearance kinetics such as glutamate. In order to address this matter, ourlaboratory has designed a ceramic-based multisite microelectrode with thecapability to detect and analyze fluctuations in extracellular glutamateconcentrations on a sub-second basis. These microelectrodes were utilized tostudy the phasic release and uptake dynamics of potassium-evoked glutamate inthe striatum of young (6 month), late-middle aged (18 month) and aged (24month) Fischer 344 rats. Our results showed a reduced glutamate clearancerate and an attenuated response to potassium depolarization in the corticostriatalprojections of aged animals in comparison to other age groups. In addition,average maximal glutamate release amplitudes were decreased in the striatumof aged animals. Pressure ejection of exogenous glutamate solution furtherconfirmed the decreased glutamate clearance ability of the aged striatum. Thesepotassium and exogenous glutamate data also highlighted a markeddorsoventral gradient in the striatum in terms of glutamate release and clearanceability. We further explored this phenomenon of age-related decreased glutamateuptake by coupling our in vivo technology with classical immunoblotting andbiotinylation techniques in order to investigate glutamate transporter regulation.Decreased glutamate clearance in the aged rats cannot be attributed to areduction in steady-state total transporter protein levels. Rather, our resultsindicate that reduced plasma membrane surface trafficking of GLAST in the agedstriatum may be partially responsible for this effect. Finally, we modified ourmicroelectrodes to study basal glutamate levels in the striatum of the aging,freely moving rat. This approach allowed us to study extracellular glutamateregulation free from the potential confounding variable of anesthesia. Our resultsdemonstrate that there is no significant alteration in basal glutamate levels inaging in the brain regions investigated. More importantly, this study validated theefficacy of the utilization of ceramic-based multisite microelectrodes for the studyof alterations in glutamate neurotransmission in the aging, freely moving rat, andit lays the foundation for future work correlating such changes with age associatedimpairments in motor function.

Résumé : Les maladies cardio-vasculaires (MCV) constituent l'une des principales causes de mortalité et de morbidité dans le monde. De nombreuses études épidémiologiques montrent que les niveaux des lipoprotéines de haute densité (HDL) sont inversement corrélés au risque des MCV. Les propriétés antiathérogènes des HDL sont attribuées, en partie, à l'action de l'enzyme Paraoxonase 1 (PON1) qui leur est associée exclusivement. Le rôle de la PON1 dans l’activité antioxydante des HDL a été largement étudié, alors que le mécanisme par lequel la PON1 exerce ses effets anti-inflammatoires reste à établir. La prévalence accrue des MCV avec l'augmentation de l'âge incite à rechercher certains facteurs qui pourraient expliquer cette tendance. Peu de travaux se sont intéressés à l'impact d'une réduction de la fonctionnalité de HDL dans le développement de l'athérosclérose et encore moins en présence d'un facteur de risque pour les MCV, tel que l'âge. À ce jour, plusieurs travaux ont mis en évidence une diminution de l'activité antioxydante de HDL et de la PON1 chez la personne âgée. Cependant, il n'existe pas de données sur l'effet de la réduction de l'activité de la PON1 sur l'activité anti-inflammatoire des HDL. Nos objectifs sont d'élucider le rôle de la PON1 dans les activités anti-inflammatoires des HDL et de déterminer l'effet de sa modulation sur l'activité athéroprotectrice des HDL chez les personnes âgées. Nos résultats montrent que la PON1 diminue significativement le niveau d'expression des molécules d'adhésion intercellulaire-1 (lCAM-1) au niveau des cellules endothéliales inhibant ainsi l'induction de l'inflammation en présence de phospholipides oxydés. Cette activité anti-inflammatoire de la PON1 est due à la fois à sa capacité de réduire l'oxydation des lipides (effet antioxydant) mais aussi à son activité phospholipase like, hydrolysant ainsi les lipides oxydés. Toutefois, cet effet anti-inflammatoire dépend de son association aux HDL. Nos résultats démontrent ainsi que l'effet anti-inflammatoire des HDL est dû en grande partie à la PON1. Cette activité des HDL diminue significativement au cours du vieillissement. Nos résultats montrent aussi que 12 semaines de consommation d'huile d'olive extra vierge (EVOO) augmentent significativement l'activité anti-inflammatoire des HDL. Cet effet est dû à une augmentation de l'activité de PON1 et d'une réduction du niveau de stress oxydant. Cet effet bénéfique de l'EVOO est plus significatif chez les personnes âgées que chez les personnes jeunes. Conclusions: Nos résultats apportent la démonstration de l'implication de la PON1 dans la régulation des activités antiathérogènes des HDL et proposent des mécanismes de l'implication de la PON1 dans la régulation de cette activité anti-inflammatoire des HDL. Aussi, nos résultats montrent l'importance de la diète de type méditerranéen dans la régulation des fonctions antiathérogènes des HDL, et plus particulièrement, en présence d'un facteur de risque pour les MCV, tel que le vieillissement. // Abstract : Cardiovascular diseases are one of the main causes of mortality and morbidity throughout the world. Several epidemiologic studies show that there is an inverse correlation between the levels of high density lipoproteins (HDL) and cardiovascular risk. The antiatherogenic properties of HDL are due, in part, to paraoxonase 1 (PON1) enzyme, which is associated exclusively to HDL. The role of PON1 in the antioxidant activity of HDL has been widely studied. However, the mechanism by which PON1 exerts its antiinflammatory effect remains to be determined. Increased prevalence of cardiovascular diseases and the increasing life span encourages investigations for certain predisposing factors that could explain this tendency. Few studies have focused on the impact of a reduction of HDL activity within the development of atherosclerosis during the aging process. Nowadays, several studies had demonstrated a reduction in the antioxidant activities of HDL and PON1 in the elderly population. However, there is no data of the effect of aging on the anti-inflamm atory activities of PON 1 and HDL. The main objectives of the present study were to explain the role of the PON1 in the anti-inflammatory properties of the HDL and to determine the effect of the modulation of PON1 activity on the atherprotective effect of HDL in the elderly population. Our results show that PON1 decreased significantly ICAM-1 expression within the endothelial cells, which inhibits the induction of inflammation in the presence of oxidized phospholipids. The anti-inflammatory activity of PON1 is due to its capacity to reduce lipid oxidation (antioxidant effect) and to its phospholipase-like activity, which consists of hydrolyzing oxidized lipids. Our results also show that 12 weeks of extra virgin oil (EVOO) increase significantly the anti-inflammatory activity of HDL. This effect is due principally to an improvement of the activity of PON1 and reduction of oxidative stress status. This beneficial effect of EVOO was more significant in the elderly than in young subjects. Conclusions: Our results demonstrate the role of the PON1 in the regulation of the antiatherogenic activities of HDL and suggest a mechanism for the implication of PON1 in the regulation of the anti-inflammatory activity of HDL. In addition, our results show the importance of the Mediterranean diet in the regulation of antiatherogenic function HDL, and particularly, in the presence of a risk factor for cardiovascular disease such as aging.

<p> Several demographers and scholars have dubbed the baby boomers&rsquo; transition to retirement as the <i>graying society</i>. Therefore, and recognizing its importance, the main objectives of this study were to learn about the transition to retirement process and its related meanings for baby boomers in the public sector. Using a mixed methodology, 382 retirees shared their perceptions on the subjects via questionnaire and 6 via interviews. This study concluded with a validation of previous authors on the importance of being prepared prior to retirement especially in the case of those with disability retirement.</p>

Background Limitations in mobility resulting from balance impairments contribute substantially to falls in older adults. Aging also has a detrimental effect on cognition which influences mobility and balance. A low cost treadmill rehabilitation platform (TRP) and a custom computer game that provided single and dual task challenges while standing and walking were used to evaluate standing balance, gait variables, visual tracking and cognition game performances in active young and older adults. Objectives The study objectives were, 1) to determine the differences in performance-based measures of standing balance, treadmill walking, visual tracking and executive cognitive function between young and older adults and 2) to examine the effect of age and dual tasks on performance-based measures of balance, gait, visual tracking and cognition in both groups. Methods Thirty active young adults (Mean age: 26.7± 2 years) and thirty older adults (Mean age 61.4± 4.4 years) performed visual tracking and cognitive game tasks on three different physical and cognitive loads on the TRP. The treadmill was instrumented with a force sense array (FSA) pressure mat to record the centre of foot pressure excursions. A motion sense air mouse (Gyration Elite) mounted on a custom made helmet was used to interact with the on screen cursor of the computer screen to perform visual tracking and cognitive game tasks. Participants were also evaluated for balance using clinical tests. Results During single tasks, younger adults performed better than older adults in the AP direction while older adults demonstrated better balance in the ML direction. Single task walking did not demonstrate a difference between the two groups. During single task cognition, there was no difference during both cognitive games while young adults did better during the closed loop visual tracking task. During the dual tasks, both groups demonstrated a dual task effect in balance, walking and cognitive tasks. Younger adults performed better than older adults in all the physical and cognitive load conditions. Conclusion The study findings provided evidence for discussion on the effects of single and dual tasking conditions in young and older adults. Understanding the effects of dual tasks has important clinical implications because older adults engage themselves in a wide variety of activities that require cognitive, mobility and balance skills simultaneously. Identifying the age at which there is a compromise on the above and providing appropriate interventions would be very useful to prevent falls.

The essays in this dissertation explore issues related to health and retirement of older Americans, using longitudinal data on older Americans from ten waves of the Health and Retirement Study (1992-2010). The first essay explores the effect of both subjective and relatively more objective physical and mental health conditions on the probability of exit from full-time employment. Eight health indices (factors) are created from a wide range of health measures by principal component analysis. The effect of these health factors on the time until exit from full-time employment is empirically examined in a proportional hazard model. Single and competing risk specifications are estimated that allow for multiple spells of full-time employment and control for unobserved heterogeneity. The main results suggest that increase in functional limitation factor makes an individual more likely to exit via any route in general and the complete retirement route in particular. For mental health problems, increase in the depression factor increases the likelihood of exit from full-time employment via the complete retirement, part-time work and unemployment routes. While increase in cognitive disorders factor has no significant effect on the likelihood of exit via complete retirement, but increases the likelihood of exit via the disability route. These results have implications for public policies targeted towards retaining older workers within the labor market. The second essay examines the effect of retirement on post retirement physical and mental health and the extent to which the effects differ across these different health outcomes. The inherent issue of reverse causality between health and retirement that leads to endogeneity is addressed by using multiple sample stratification and instrumental variable estimation strategies. The stratified samples include individuals who are physically and mentally healthy prior to their retirement so that pure effect of retirement on post retirement health may be found. Five different instruments for complete retirement are also used to deal with endogeneity. The sample stratification results unanimously indicate that complete retirement has adverse effect on post retirement physical and mental health. While the instrumental variables approach results are mixed and are based on the choice of instrument for complete retirement.

<p> Participants (N= 227) completed questionnaires pertaining to depressive symptomatology and trait intrusive thinking, and subsequently engaged in tasks assessing executive functioning, working memory, prospective memory, and episodic memory. The dependent variables assessed the influence of intrusive thinking on the relationship between depressive symptomatology and the four previously mentioned cognitive domains. A three-way interaction was conducted using the PROCESS macro created by Hayes (2013). The results revealed a significant three-way interaction for the working and episodic memory measure. Younger participants with low levels of intrusive thinking performed better on the working and episodic memory task as depressive symptomatology increased, while older adults with low levels of intrusive thinking performed worse on these tasks as depressive symptomatology increased. It is important to note that performance on these measures did not significantly vary by depressive symptomatology at high levels of intrusive thinking. These findings suggest that intrusive thinking may be a beneficial factor to explore in future research regarding the impact of depressive symptomatology on cognitive functioning across age groups.</p>