The prevalence of obesity is high in the United States. One of the many concerns with the high prevalence of obesity is its association with an increased risk of falls and subsequent injury. Thus, it is important to understand factors affecting falls among individuals who are obese, to help develop effective intervention solutions to mitigate falls in this population. Obese individuals have been hypothesized to have an impaired plantar sensitivity, and this may influence their balance control, thus lead to more falls. Executive function deficits in individuals who are obese may affect their ability to allocate attentional resources to dual tasks (walking while performing other tasks), and may put them at higher risks of falls. Gait alterations and muscle strength deficits in individuals who are obese may also increase their fall risks. Therefore, three studies were carried out to provide better understanding into the factors affecting falls in individuals who are obese. The first study investigated the effects of obesity on plantar sensitivity, and explored the relationship between plantar sensitivity and postural sway during quiet standing. Plantar sensitivity was measured as the force threshold at which an increasing force applied to the plantar surface of the foot was first perceived, and the force threshold at which a decreasing force was last perceived. Measurements were obtained while standing, and at two locations on the plantar surface of the dominant foot. Postural sway during quiet standing was then measured under three different sensory conditions. Results indicated less sensitive plantar sensitivity and increased postural sway among individuals who are obese, and statistically significant correlations between plantar sensitivity and postural sway that were characterized as weak to moderate in strength. As such, impaired plantar sensitivity among individuals who are obese may be a mechanism by which obesity degrades standing balance among these individuals. The second study investigated the influence of obesity on executive function, and determined whether there is a relationship between executive function and fall risk (as estimated from selected gait parameters). Four major components of executive function were assessed, including selective attention, divided attention, semantic memory and working memory. Both single- and dual-task walking (walking-while-talking) were completed to evaluate fall risk during gait. Less effective selective attention, semantic memory, and working memory were found among young obese adults. Participants exhibited higher fall risks during dual-task walking, and executive function scores were associated with gait during dual-task walking. In conclusion, obese individuals exhibited less effective executive function, which may be associated with their increased fall risk. The third study explored differences in gait, plantar sensitivity, executive function, lower extremity muscle strength, and body size between fallers and non-fallers, and the strength of the association between the same factors and slip severity. Participants' gait, plantar sensitivity, executive function, lower extremity muscle strength, and body size measures were obtained. An unexpected slip was introduced in a laboratory setting to obtain slip severity related measures and slip outcome. Results indicated obese fallers exhibited better executive function (selective attention), stronger lower extremity muscle strength, lower BMI and smaller waist circumference. Results also indicated increased slip severity was associated with faster walking speed, longer step length, higher RCOF, worse executive function (working memory), and lower BMI. Slower reactive recovery response was also associated with lower BMI. As such, better selective attention and stronger muscle strength exhibited limited benefit in slip recovery among individuals who are obese. Altered gait pattern, and working memory may be factors by which obesity increased slip severity, and lower BMI among individuals who are obese may increase slip-induced fall risks. In conclusion, reduced plantar sensitivity, impairments in executive function, altered gait pattern were associated with deficits in standing and walking balance control, and increased slip severity among individuals who are obese. Therefore, appropriate fall prevention/intervention program targeting at some or all of these factors may be considered as solutions to decrease fall risks for obese individuals. / Ph. D.

Inhibitory Control (IC), a vital facet of childhood development, involves the ability to suppress a dominant response, as well as the ability to suppress irrelevant thoughts and behaviors. This ability emerges during the first year of life and develops rapidly during the preschool years. A variety of tasks have been developed to measure IC in this age group and, recently, research has demonstrated important differences in task performance according to various distinctions among these tasks. One under-researched distinction is that of whether an IC task requires the child to give a verbal or a motoric response. Therefore, the purpose of this study was to examine, in 4-year-old children, the differences and similarities among IC tasks requiring either a verbal or a motoric response. Differences were explored with respect to the contributions to verbal and motoric IC performance of language, intelligence, temperament, and frontal encephalography, as well as with respect to social and school readiness outcomes. IC was best described by a two-component model, distinguishing verbal and motoric IC. Both baseline and task electrophysiology contributed to task performance in the verbal Yes-No task as well as the motoric IC composite. Language and intelligence, too, were associated with both verbal and motoric IC, although nonverbal intelligence was less strongly correlated with verbal IC than it was with motoric IC. All laboratory measures of IC related to parent report of children’s IC as well as to other parent-reported temperament scales and factors. Children’s verbal and motoric IC were associated, too, with children’s social development, surprisingly showing the most consistent associations with social inhibition. Asocial behavior positively correlated more strongly with motoric IC than with verbal IC. Children’s laboratory IC positively correlated with their school readiness, even when controlling for their intelligence although children’s emergent literacy more positively related to their motoric, rather than verbal, IC. An interaction of intelligence and IC contributed to social variables, but not to school readiness. This research supports the important distinction between verbal and motoric IC, and demonstrates the utility of including an array of measures of both in early childhood research. / Ph. D.

Social cognition is a set of complex processes that mediate much of human behavior. The development of these skills is related to and interdependent on other cognitive processes, particularly inhibitory control, which allows for willful suppression of dominant responses. Many aspects of social behavior rely on inhibitory control to moderate impulsive or socially inappropriate behaviors and process complex perspective-taking. Furthermore, the brain regions associated with inhibitory control and social cognition overlap functionally and structurally. I review neurodevelopmental literature to suggest that social cognition is developmentally dependent on inhibitory control and that the neural foundations of both these skills are measurable in infancy. I tested this model using growth curve and structural equation modeling and show that 10-month, but not 5-month, frontotemporal coherence predicts social cognition in late childhood through preschool inhibitory control. These findings provide insight into the neurodevelopmental trajectory of cognition and suggest that connectivity from frontal regions to other parts of the brain is a foundation for the development of these skills. / Doctor of Philosophy / Social cognition is the ability to understand and interpret another’s thoughts, words, and actions and inhibitory control is the ability to suppress one’s own thoughts, words, and actions. These two types of cognition are similar and use the same brain regions, and I suggest that inhibitory control underlies much of social cognition. In order to test this, I examined children’s inhibitory control and brain connectivity at 5 months, 10 months, 24 months, 48 months, and 9 years and measured social cognition at 9 years. I found that connectivity between the frontal and temporal lobes at 10 months predicted inhibitory control and 48-months, which then predicted social cognition at 9 years. This suggests that infant brain connectivity sets the stage for developing inhibitory control, which is important for later social cognition

Relatively few studies have investigated the relationship between executive functioning (EF) and language development, and even fewer have researched hot and cool EF as a predictor language development. This study is an investigation into the relationship between EF and language development in preschool aged children. More specifically, the ability for hot or cool EF to predict language, this will be the focus of the study. It was found that hot EF was a better predictor of language development in preschool aged children.

No description available.

Behavior-analytic accounts of rule-adherence behavior suggest that rule-governance is a general class of functional (i.e., instrumental) behavior maintained by social consequences (Baum, 2005; Malott & Suarez, 2004; Jacobs et al., in prep.). Evolutionary Life-History (LH) theory suggests that LH strategy may underlie variation in rule-adherence behavior. Based on an integration of these two theories, a theoretical structural model of rule-governance was developed and tested. The structure of this model was used to develop follow-up experiments to test particularly salient links in the model. Consistent with theory, the structural model indicated that slow LH strategy directly and indirectly (through increased moral emotions and increased executive functioning) contributed to strength of rule-governance. Two experiments failed to replicate previously demonstrated effects of executive function depletion or moral identity priming (on moral behavioral outcome measures). Further, self-report measures of slow LH strategy, executive functioning, and rule-governance did not predict prosocial (donating) or rule-defiance (cheating) behavior in laboratory tasks. The limitations of relying solely on either self-report or behavioral tasks of unknown external validity are discussed.

Cognitive impairment in coronary artery disease (CAD) patients can predict poorer quality of life, dementia, and increased mortality. This study aimed to determine the association between long-term cortisol elevations and cognitive function in CAD patients. Participants were recruited at the beginning of a 1 year cardiac rehabilitation program and followed forward. Composite Z-scores were computed from tests measuring memory and executive function at baseline and 1 year. Cortisol deposition (3 months) was measured from a 20 mg, 3 cm hair sample. Analyses of covariance showed less improvement in memory function (F1,50=4.721, p=0.035) but not executive function (F1,49=0.318, p=0.575) in patients dichotomized into a high cortisol group based on a previously established reference range. Prolonged cortisol elevation may be associated with cognitive changes in subjects with CAD.

The current study examined the phonological process of prosodic ability in a model of adult word reading and reading comprehension ability. All phonological tasks involve executive functions (EF) reflected in an individual’s flexibility for manipulating different components of language. To account for the EF demands involved in phonological tasks of reading, EF was assessed using measures of inhibitory control and switching attention as both a control variable and predictor in each model of reading. Two research questions guided the study: 1) Do prosodic ability and EF make independent contributions to word reading, and reading comprehension ability when controlling for the other? 2) Do prosodic ability and EF make unique contributions to word reading, and reading comprehension ability when controlling for the other, in addition to controlling for vocabulary, fluid (nonverbal) intelligence, rapid automatized naming (RAN - Digits), and phonological short-term memory (PSTM)? Participants were one hundred and three native-English speaking adults (18 to 55 years of age) recruited from Eastern Ontario. A total of 8 regression models were tested. The analyses revealed unique contributions of prosodic ability in adult word reading achievement, and EF in silent reading comprehension. Prosody’s contribution to word reading above EF supports prosodic awareness as a phonological skill that can be used to explain individual differences in word reading, whereas EF’s contribution to reading comprehension supports its’ role in more complex reading tasks. Prosody and EF represent constructs that warrant future consideration in models of reading. / Thesis (Master, Education) -- Queen's University, 2013-12-19 16:15:50.64

Cognitive impairment in coronary artery disease (CAD) patients can predict poorer quality of life, dementia, and increased mortality. This study aimed to determine the association between long-term cortisol elevations and cognitive function in CAD patients. Participants were recruited at the beginning of a 1 year cardiac rehabilitation program and followed forward. Composite Z-scores were computed from tests measuring memory and executive function at baseline and 1 year. Cortisol deposition (3 months) was measured from a 20 mg, 3 cm hair sample. Analyses of covariance showed less improvement in memory function (F1,50=4.721, p=0.035) but not executive function (F1,49=0.318, p=0.575) in patients dichotomized into a high cortisol group based on a previously established reference range. Prolonged cortisol elevation may be associated with cognitive changes in subjects with CAD.

Deficits in executive function are commonly reported following Traumatic Brain Injury (TBI) and are important for establishing functional impairments. Understanding the nature of executive dysfunction following TBI is often complicated by secondary factors that can impact measured ability. This study sought to clarify the persistent effects of TBI on executive function, as measured by the Wisconsin Card Sorting Test (WCST), while accounting for effort given during testing, as measured by the Portland Digit Recognition Test. Results suggested a dose-response relationship between TBI severity and subsequent WCST deficits. Mild TBI patients who provided good effort during testing showed no observable differences from locally matched controls on WCST performance. Effort during testing was found to have a larger overall effect on WCST performance than moderate-to-severe TBI or dementia. The present study highlights the need to account for secondary factors, such as effort during testing, to accurately measure cognitive dysfunction following compensable injuries.