ERP and cardiovascular correlates of source memory discrimination in older and younger adults /

There is much evidence to support an age-related decline in source memory ability. However, the underlying mechanisms responsible for this decline are not well understood. The current study was carried out to determine the electrophysiological correlates of source memory discrimination in younger and older adults. Event-related potentials (ERPs) and continuous electrocardiographic (ECG) data were collected from younger (M= 21 years) and older (M= 71 years) adults during a source memory task. Older adults were more likely to make source memory errors for recently repeated, non-target words than were younger adults. Moreover, their ERP records for correct trials showed an increased amplitude in the late positive (LP) component (400-800 msec) for the most recently presented, non-target stimuli relative to the LP noted for target items. Younger adults showed an opposite pattern, with a large LP component for target items, and a much smaller LP component for the recently repeated non-target items. Computation of parasympathetic activity in the vagus nerve was performed on the ECG data (Porges, 1985). The resulting measure, vagal tone, was used as an index of physiological responsivity. The vagal tone index of physiological responsivity was negatively related to the LP amplitude for the most recently repeated, non-target words in both groups, after accounting for age effects. The ERP data support the hypothesis that the tendency to make source memory errors on the part of older adults is related to the ability to selectively control attentional processes during task performance. Furthermore, the relationship between vagal tone and ERP reactivity suggests that there is a physiological basis to the heightened reactivity measured in the LP response to recently repeated non-target items such that, under decreased physiological resources, there is an impairment in the ability to selectively inhibit bottom-up, stimulus based properties in favour of task-related goals in older adults. The inconsistency of these results with other explanatory models of source memory deficits is discussed. It is concluded that the data are consistent with a physiological reactivity model requiring inhibition of reactivity to irrelevant, but perceptually-fluent, stimuli.

Autonomic and electrocortical indices of performance monitoring and source memory discrimination in older and younger adults

Reduced capacity for executive cognitive function and for the autonomic control of cardiac responsivity are both concomitants of the aging process. These may be linked through their mutual dependence on medial prefrontal function, but the specifics ofthat linkage have not been well explored. Executive functions associated with medial prefrontal cortex involve various aspects ofperformance monitoring, whereas centrally mediated autonomic functions can be observed as heart rate variability (HRV), i.e., variability in the length of intervals between heart beats. The focus for this thesis was to examine the degree to which the capacity for phasic autonomic adjustments to heart rate relates to performance monitoring in younger and older adults, using measures of electrocortical and autonomic activity. Behavioural performance and attention allocation during two age-sensitive tasks could be predicted by various aspects of autonomic control. For young adults, greater influence of the parasympathetic system on HRV was beneficial for learning unfamiliar maze paths; for older adults, greater sympathetic influence was detrimental to these functions. Further, these relationships were primarily evoked when the task required the construction and use of internalized representations of mazes rather than passive responses to feedback. When memory for source was required, older adults made three times as many source errors as young adults. However, greater parasympathetic influence on HRV in the older group was conducive to avoiding source errors and to reduced electrocortical responses to irrelevant information. Higher sympathetic predominance, in contrast, was associated with higher rates of source error and greater electrocortical responses tq non-target information in both groups. These relations were not seen for 11 errors associated with a speeded perceptual task, irrespective of its difficulty level. Overall, autonomic modulation of cardiac activity was associated with higher levels of performance monitoring, but differentially across tasks and age groups. With respect to age, those older adults who had maintained higher levels of autonomic cardiac regulation appeared to have also maintained higher levels of executive control over task performance.

Autonomic prediction of error-related ERP components in perceptual and conceptual tasks in older and younger adults

In studies of cognitive processing, the allocation of attention has been consistently linked to subtle, phasic adjustments in autonomic control. Both autonomic control of heart rate and control of the allocation of attention are known to decline with age. It is not known, however, whether characteristic individual differences in autonomic control and the ability to control attention are closely linked. To test this, a measure of parasympathetic function, vagal tone (VT) was computed from cardiac recordings from older and younger adults taken before and during performance of two attentiondemanding tasks - the Eriksen visual flanker task and the source memory task. Both tasks elicited event-related potentials (ERPs) that accompany errors, i.e., error-related negativities (ERNs) and error positivities (Pe's). The ERN is a negative deflection in the ERP signal, time-locked to responses made on incorrect trials, likely generated in the anterior cingulate. It is followed immediately by the Pe, a broad, positive deflection which may reflect conscious awareness of having committed an error. Age-attenuation ofERN amplitude has previously been found in paradigms with simple stimulus-response mappings, such as the flanker task, but has rarely been examined in more complex, conceptual tasks. Until now, there have been no reports of its being investigated in a source monitoring task. Age-attenuation of the ERN component was observed in both tasks. Results also indicated that the ERNs generated in these two tasks were generally comparable for young adults. For older adults, however, the ERN from the source monitoring task was not only shallower, but incorporated more frontal processing, apparently reflecting task demands. The error positivities elicited by 3 the two tasks were not comparable, however, and age-attenuation of the Pe was seen only in the more perceptual flanker task. For younger adults, it was Pe scalp topography that seemed to reflect task demands, being maximal over central parietal areas in the flanker task, but over very frontal areas in the source monitoring task. With respect to vagal tone, in the flanker task, neither the number of errors nor ERP amplitudes were predicted by baseline or on-task vagal tone measures. However, in the more difficult source memory task, lower VT was marginally associated with greater numbers of source memory errors in the older group. Thus, for older adults, relatively low levels of parasympathetic control over cardiac response coincided with poorer source memory discrimination. In both groups, lower levels of baseline VT were associated with larger amplitude ERNs, and smaller amplitude Pe's. Thus, low VT was associated in a conceptual task with a greater "emergency response" to errors, and at the same time, reduced awareness of having made them. The efficiency of an individual's complex cognitive processing was therefore associated with the flexibility of parasympathetic control of heart rate, in response to a cognitively challenging task.

Effects of age on learning a spatial motor task in younger and older adults individualizing their knowledge of results schedule

Self-controlled KR practice has revealed that providing participants the opportunity to control their KR is superior for motor learning compared to participants replicating the KR schedule of a self-control participant, without the choice (e.g., yoked). The purpose of the present experiment was two-fold. First, to examine the utility of a self-controlled KR schedule for learning a spatial motor task in younger and older adults and second, to determine whether a self-controlled KR schedule facilitates an increased ability to estimate one’s performance in retention and transfer. Twenty younger adults and 20 older adults practiced in either the self-control or yoked condition and were required to push and release a slide along a confined pathway using their non-dominant hand to a target distance. The retention data revealed that as a function of age, a self-controlled KR schedule facilitated superior retention performance and performance estimations in younger adults compared to their yoked counterparts.

Age-related changes in ERPs associated with context-based and response-based interference

Age-related differences in information processing have often been explained through deficits in older adults' ability to ignore irrelevant stimuli and suppress inappropriate responses through inhibitory control processes. Functional imaging work on young adults by Nelson and colleagues (2003) has indicated that inferior frontal and anterior cingulate cortex playa key role in resolving interference effects during a delay-to-match memory task. Specifically, inferior frontal cortex appeared to be recruited under conditions of context interference while the anterior cingulate was associated with interference resolution at the stage of response selection. Related work has shown that specific neural activities related to interference resolution are not preserved in older adults, supporting the notion of age-related declines in inhibitory control (Jonides et aI., 2000, West et aI., 2004b). In this study the time course and nature of these inhibition-related processes were investigated in young and old adults using high-density ERPs collected during a modified Sternberg task. Participants were presented with four target letters followed by a probe that either did or did not match one of the target letters held in working memory. Inhibitory processes were evoked by manipulating the nature of cognitive conflict in a particular trial. Conflict in working memory was elicited through the presentation of a probe letter in immediately previous target sets. Response-based conflict was produced by presenting a negative probe that had just been viewed as a positive probe on the previous trial. Younger adults displayed a larger orienting response (P3a and P3b) to positive probes relative to a non-target baseline. Older adults produced the orienting P3a and 3 P3b waveforms but their responses did not differentiate between target and non-target stimuli. This age-related change in response to targetness is discussed in terms of "early selection/late correction" models of cognitive ageing. Younger adults also showed a sensitivity in their N450 response to different levels of interference. Source analysis of the N450 responses to the conflict trials of younger adults indicated an initial dipole in inferior frontal cortex and a subsequent dipole in anterior cingulate cortex, suggesting that inferior prefrontal regions may recruit the anterior cingulate to exert cognitive control functions. Individual older adults did show some evidence of an N450 response to conflict; however, this response was attenuated by a co-occurring positive deflection in the N450 time window. It is suggested that this positivity may reflect a form of compensatory activity in older adults to adapt to their decline in inhibitory control.

Electrocortical indices of cognitive control in working memory : exploring the effects of proactive interference, cognitive load, and aging

Cognitive control involves the ability to flexibly adjust cognitive processing in order to resist interference and promote goal-directed behaviour. Although frontal cortex is considered to be broadly involved in cognitive control, the mechanisms by which frontal brain areas implement control functions are unclear. Furthermore, aging is associated with reductions in the ability to implement control functions and questions remain as to whether unique cortical responses serve a compensatory role in maintaining maximal performance in later years. Described here are three studies in which electrophysiological data were recorded while participants performed modified versions of the standard Sternberg task. The goal was to determine how top-down control is implemented in younger adults and altered in aging. In study I, the effects of frequent stimulus repetition on the interference-related N450 were investigated in a Sternberg task with a small stimulus set (requiring extensive stimulus resampling) and a task with a large stimulus set (requiring no stimulus resampling).The data indicated that constant stimulus res amp ling required by employing small stimulus sets can undercut the effect of proactive interference on the N450. In study 2, younger and older adults were tested in a standard version of the Sternberg task to determine whether the unique frontal positivity, previously shown to predict memory impairment in older adults during a proactive interference task, would be associated with the improved performance when memory recognition could be aided by unambiguous stimulus familiarity. Here, results indicated that the frontal positivity was associated with poorer memory performance, replicating the effect observed in a more cognitively demanding task, and showing that stimulus familiarity does not mediate compensatory cortical activations in older adults. Although the frontal positivity could be interpreted to reflect maladaptive cortical activation, it may also reflect attempts at compensation that fail to fully ameliorate agerelated decline. Furthermore, the frontal positivity may be the result of older adults' reliance on late occurring, controlled processing in contrast to younger adults' ability to identify stimuli at very early stages of processing. In the final study, working memory load was manipulated in the proactive interference Sternberg task in order to investigate whether the N450 reflects simple interference detection, with little need for cognitive resources, or an active conflict resolution mechanism that requires executive resources to implement. Independent component analysis was used to isolate the effect of interference revealing that the canonical N450 was based on two dissociable cognitive control mechanisms: a left frontal negativity that reflects active interference resolution, , but requires executive resources to implement, and a right frontal negativity that reflects global response inhibition that can be relied on when executive resources are minimal but at the cost of a slowed response. Collectively, these studies advance understanding of the factors that influence younger and older adults' ability to satisfy goal-directed behavioural requirements in the face of interference and the effects of age-related cognitive decline.

Autonomic and Electrophysiological Correlates of Cognitive Control in Aging

This thesis tested a model of neurovisceral integration (Thayer & Lane, 2001) wherein parasympathetic autonomic regulation is considered to play a central role in cognitive control. We asked whether respiratory sinus arrhythmia (RSA), a parasympathetic index, and cardiac workload (rate pressure product, RPP) would influence cognition and whether this would change with age. Cognitive control was measured behaviourally and electrophysiologically through the error-related negativity (ERN) and error positivity (Pe). The ERN and Pe are thought to be generated by the anterior cingulate cortex (ACC), a region involved in regulating cognitive and autonomic control and susceptible to age-related change. In Study 1, older and younger adults completed a working memory Go/NoGo task. Although RSA did not relate to performance, higher pre-task RPP was associated with poorer NoGo performance among older adults. Relations between ERN/Pe and accuracy were indirect and more evident in younger adults. Thus, Study 1 supported the link between cognition and autonomic activity, specifically, cardiac workload in older adults. In Study 2, we included younger adults and manipulated a Stroop task to clarify conditions under which associations between RSA and performance will likely emerge. We varied task parameters to allow for proactive versus reactive strategies, and motivation was increased via financial incentive. Pre-task RSA predicted accuracy when response contingencies required maintenance of a specific item in memory. Thus, RSA was most relevant when performance required proactive control, a metabolically costly strategy that would presumably be more reliant on autonomic flexibility. In Study 3, we included older adults and examined RSA and proactive control in an additive factors framework. We maintained the incentive and measured fitness. Higher pre-task RSA among older adults was associated with greater accuracy when proactive control was needed most. Conversely, performance of young women was consistently associated with fitness. Relations between ERN/Pe and accuracy were modest; however, isolating ACC activity via independent component analysis allowed for more associations with accuracy to emerge in younger adults. Thus, performance in both groups appeared to be differentially dependent on RSA and ACC activation. Altogether, these data are consistent with a neurovisceral integration model in the context of cognitive control.

Wellspring: an intrinsic case study of community-based education for adults living with cancer /

This paper presents education research as vital to addressing the issues faced by adults living with cancer. This qualitative study looked at philosophies of practice for cancer patient education. It was about understanding how values and beliefs shape the way program planners and managers operationalize their knowledge of adult education and how this has significant impact on meeting the needs of those touched by cancer. Improved technology has extended life expectancy, so that Canadians living with cancer, or even dying with cancer now spend less time in direct medical care. The notion of cancer as simply a medical concern is outdated. This study found that informational and support needs of adults living with cancer are often unmet, ignored or unknown. This research investigated a community-based education initiative that is inviting, accessible, and promotes a sense of hope. More specifically, this case study uncovered factors contributing to the success of Wellspring, a grass-roots cancer patient support centre which has been recognized nationally for its ability to effectively meet the diverse non-medical supportive care needs of as many cancer patients and caregivers as possible. Therefore, Wellspring was selected as a case study. Educating people to take charge of their own lives and supporting them in making informed decisions about their lifestyle choices made Wellspring part of a social action movement that focused on improving social attitudes toward people living with cancer. Results of this descriptive inquiry and philosophical inquiry evolved into data that was used to devise an organic model of community-based education that encompasses Adler's (1993) four dimensions of philosophy within a socio-cultural context.

Attention focus and balance control in young and older adults

This thesis investigated attention focus and balance control in eighteen healthy young adults and eighteen healthy older adults. All participants performed sixteen consecutive trials of a balance task which involved standing for 30-s on an unstable platform that could rotate only in the roll direction. There were no attention focus instructions provided on any of the sixteen trials. Following the completion of the initial and final attempt in the series, participants reported "where" their attention had been focused when performing the task. The results showed differences in balance between young and older adults and improvements in balance with practice in both young and older adults. However, there were no differences in attention focus strategies between young and older adults. Both age groups directed attention to multiple sources during the balance task. An equal focus on internal (i.e., feet, trunk, and other body parts) and external (i.e., the platform) sources with little focus on events not related to the task dominated on the first attempt of the balance task. Focus on internal sources was maintained and focus on events not related to the task increased at the expense of focus on external sources on the final attempt of the balance task. Following the series of sixteen trials to establish "natural" attention focus, participants performed three randomly presented trials, each with specific attention focus instructions (i.e., think about minimizing movements of the feet, the trunk, or the platform). The results showed that, in contrast to the literature, instructions to focus on an internal source, the trunk, actually augmented control of the task as reflected in reduced trunk sway whereas instructions to focus on an internal source, the feet, or an external source, the platform, did not benefit performance on the task. Thus, the distance fi-om the interaction point of the body with the external source is critical and may not depend on whether the source is internal or external. Thus, a global attention focus instruction may not be beneficial and the nature of the task should be considered when adopting attention focus instructions for young and older adults.

A Study of role conflict, role ambiguity, locus of control, job satisfaction and participation in decision making among front-line vocational service workers for mentally retarded adults

This study was an investigation of individual and organizational factors, as perceived by front-line vocational service workers from Adult Rehabilitation Centres (ARC Industries) for mentally retarded adults. The specific variables which were measured included role conflict/role ambiguity (role factors), internal/external locus of control (individual differences), job satisfaction with work and supervision (job attitudes) and participation in deci~ion making (organizational factor). The exploration of these constructs was conducted by means of self-report questionnaires which were completed by sixty-nine out of a total of ninety front-line employees. The surveys were distributed in booklet form to nine distinct rehabilitation facilities from St. Catharines, West Lincoln, Greater Niagara, Port Colborne, WeIland, Fort Erie, Hamilton, Guelph and Brantford. The survey data was evaluated by the statisti.cal Package for the Social Sciences (SPSS) which used the Pearson Product Moment Correlation procedure and a compar~son of means test. A comparison of correlation coefficients test was also conducted. This statistical procedure was calculated mathematically. The results obtained from the statistical evaluation confirmed the prediction that self-reported measures of participation in decision making and satisfaction (work and supervision) would be negatively correlated with role conflict and role ambiguity. As well, the speculation that perceived satisfaction (work and supervision) would be positively correlated with participation in decision making was empirically supported. Internal and external locus of control did not contribute to a significant difference in r~sponses to role perceptions (conflict and ambiguity) , satisfaction (work and supervision) or the correlational relationship between participation in decision making and satisfaction (work and supervision). Overall, the findings from this study substantiated the importance of examining employee perceptions in the workplace and the interrelationships among individual and organizational variables. This research was considered a contribution to the general area of occupational stress and to the study of individuals in work organizations.

Preadjunct questions as a learning strategy for older adults

This study investigated the effectiveness of comprehension level preadjunct questions as a learning strategy for older adults in a classroom setting. Fifty-five adults from 55 to 70 years of age were randomly assigned to two groups, the preadjunct question group and a no-question control group. They viewed a video on high blood pressure and completed a recall posttest immediately after viewing the video and again seven days tater. Results demonstrated that there was no significant difference between groups. However, the no-question control group obtained a higher mean score on both the immediate and delayed recall tests than did the preadjunct question group. Nevertheless, significant differences in posttest scores were found related to educational levels and prior knowledge about high blood pressure. Results obtained were explained in terms of resource theory of cognitive aging.

The Effectiveness of the precision fluency shaping program controlling stuttering behaviour in adults

This study was done to test the effectiveness of the Precision Fluency Shaping Program in controlling stuttering behaviour in adults. Two sites were chosen, each using the Precision Fluency Shaping Program to treat stuttering. At each clinic, a Speech Patbologist made a random selection of the subjects' pre- and post-therapy video-taped interviews, totalling 20 in all. During the interviews, the clients were asked questions and re~d a short passage to determine the frequency of stuttering in natural conversation and in reading. Perceptions of Stuttering Inventory questionnaires vvere also filled in before and after therapy. Two judges were trained to identify stuttering behaviour, and were given an inter-rater reliability test at selected intervals throughout the study. Protocols",:m.a;d;6 of each interview tape, were scored for (a) stuttering behaviour and (b) words spoken or read. An Analysis of Variance Repeated Measures Test was used to compare before and after scores of conversations, readings, and Perceptions of Stuttering Inventory to determine whether the Precision Fluency Shaping Program controlled stuttering behaviour significantly. A Pearson R Correlation Test was also administered to determine if a relationship existed bet\veen Perceptions of Stuttering Inventory and (i) conversation and (ii) reading scores.

The effect of literacy training on the self-concept of moderately mentally handicapped adults

In this single group, pretest/posttest design study the literacy level and self-concept of nine moderately mentally handicapped adults was assessed. The participants in the study were involved in reading lessons using the Ball-Stick-Bird reading system, a brainbased program. No significant differences were found in either literacy level or reading level after intervention. However, there were changes in reading behaviour. These changes occurred in the subskills ofdirectionality, letter-sound correspondence, wordreading, and use of reading materials.

Why do some adults change their minds about what is important in the visual arts? : a case study

This-~-case study used ethnographic-methodo-logy. --The research project was an introductory study of one adult's present and past experiences with the visual arts, exploring, in particular, the causes and processes that were related to the individual's changes of mind in order to develop an understanding of why that individual had changed her mind about what was significant in the visual arts. The individual who provided the data was a solid supporter of art galleries: female, middle-aged, graduate of university and college, married with two children, and living in an urban community. The data were collected from two informal conversational interviews and from a written description of one change experience selected by the participant. The individual had positive experiences with art during early childhood, in elementary and secondary school, during university, in avocational drawing and painting studio courses, and in aesthetic experiences. All of these experiences have had individual effects and, together, they have had a cumulative effect on the development of the participant's opinions and ideas about the visual arts. The experiences which had the most effect on the development of the individual's perspectives on the visual arts were handson studio, educational, and aesthetic experiences. Further research is suggested to investigate why some adults change their minds about the visual arts.

Developmental and individual differences in novelty and error detection in 10-year-old children and young adults /

Event-related potentials were recorded from 10-year-old children and young adults in order to examine the developmental dififerences in two frontal lobe functions: detection of novel stimuli during an auditory novelty oddball task, and error detection during a visual flanker task. All participants showed a parietally-maximal P3 in response to auditory stimuli. In children, novel stimuli generated higher P3 amplitudes at the frontal site compared with target stimuli, whereas target stimuli generated higher P3 amplitudes at the parietal site compared with novel stimuli. Adults, however, had higher P3 amplitude to novel tones compared with target tones at each site. Children also had greater P3 amplitude at more parietal sites than adults during the novelty oddball and flanker tasks. Furthermore, children and adults did not show a significant reduction in P3 amplitude from the first to second novel stimulus presentation. No age differences were found with respect to P3 latency to novel and target stimuli. These findings suggest that the detection of novel and target stimuli is mature in 10-year-olds. Error trials typically elicit a negative ERP deflection (the ERN) with a frontal-central scalp distribution that may reflect response monitoring. There is also evidence of a positive ERP peak (the Pe) with a posterior scalp distribution which may reflect subjective recognition of a response. Both children and adults showed an ERN and Pe maximal at frontal-central sites. Children committed more errors, had smaller ERN across sites, and had a larger Pe at the parietal site than adults. This suggests that response monitoring is still immature in 10-year-olds whereas recognition of and emotional responses to errors may be similar in children and adults.