Matching Items (5)
Filtering by
- All Subjects: Sensorimotor
- All Subjects: Adolescence
- All Subjects: Arm Configuration
- Creators: Presson, Clark
- Member of: Theses and Dissertations
Description
Motor behavior is prone to variable conditions and deviates further in disorders affecting the nervous system. A combination of environmental and neural factors impacts the amount of uncertainty. Although the influence of these factors on estimating endpoint positions have been examined, the role of limb configuration on endpoint variability has been mostly ignored. Characterizing the influence of arm configuration (i.e. intrinsic factors) would allow greater comprehension of sensorimotor integration and assist in interpreting exaggerated movement variability in patients. In this study, subjects were placed in a 3-D virtual reality environment and were asked to move from a starting position to one of three targets in the frontal plane with and without visual feedback of the moving limb. The alternating of visual feedback during trials increased uncertainty between the planning and execution phases. The starting limb configurations, adducted and abducted, were varied in separate blocks. Arm configurations were setup by rotating along the shoulder-hand axis to maintain endpoint position. The investigation hypothesized: 1) patterns of endpoint variability of movements would be dependent upon the starting arm configuration and 2) any differences observed would be more apparent in conditions that withheld visual feedback. The results indicated that there were differences in endpoint variability between arm configurations in both visual conditions, but differences in variability increased when visual feedback was withheld. Overall this suggests that in the presence of visual feedback, planning of movements in 3D space mostly uses coordinates that are arm configuration independent. On the other hand, without visual feedback, planning of movements in 3D space relies substantially on intrinsic coordinates.
ContributorsRahman, Qasim (Author) / Buneo, Christopher (Thesis director) / Helms Tillery, Stephen (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
Motor behavior is prone to variable conditions and deviates further in disorders affecting the nervous system. A combination of environmental and neural factors impacts the amount of uncertainty. Although the influence of these factors on estimating endpoint positions have been examined, the role of limb configuration on endpoint variability has been mostly ignored. Characterizing the influence of arm configuration (i.e. intrinsic factors) would allow greater comprehension of sensorimotor integration and assist in interpreting exaggerated movement variability in patients. In this study, subjects were placed in a 3-D virtual reality environment and were asked to move from a starting position to one of three targets in the frontal plane with and without visual feedback of the moving limb. The alternating of visual feedback during trials increased uncertainty between the planning and execution phases. The starting limb configurations, adducted and abducted, were varied in separate blocks. Arm configurations were setup by rotating along the shoulder-hand axis to maintain endpoint position. The investigation hypothesized: 1) patterns of endpoint variability of movements would be dependent upon the starting arm configuration and 2) any differences observed would be more apparent in conditions that withheld visual feedback. The results indicated that there were differences in endpoint variability between arm configurations in both visual conditions, but differences in variability increased when visual feedback was withheld. Overall this suggests that in the presence of visual feedback, planning of movements in 3D space mostly uses coordinates that are arm configuration independent. On the other hand, without visual feedback, planning of movements in 3D space relies substantially on intrinsic coordinates.
ContributorsRahman, Qasim (Author) / Buneo, Christopher (Thesis director) / Helms Tillery, Stephen (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
The premise of the embodied cognition hypothesis is that cognitive processes require emotion, sensory, and motor systems in the brain, rather than using arbitrary symbols divorced from sensorimotor systems. The hypothesis explains many of the mechanisms of mental simulation or imagination and how they facilitate comprehension of concepts. Some forms of embodied processing can be measured using electroencephalography (EEG), in a particular waveform known as the mu rhythm (8-13 Hz) in the sensorimotor cortex of the brain. Power in the mu band is suppressed (or de-synchronized) when an individual performs an action, as well as when the individual imagines performing the action, thus mu suppression measures embodied imagination. An important question however is whether the sensorimotor cortex involvement while reading, as measured by mu suppression, is part of the comprehension of what is read or if it is arises after comprehension has taken place. To answer this question, participants first took the Gates-MacGinitie reading comprehension test. Then, mu-suppression was measured while participants read experimental materials. The degree of mu-suppression while reading verbs correlated .45 with their score on the Gates-MacGinitie test. This correlation strongly suggests that the sensorimotor system involvement while reading action sentences is part of the comprehension process rather than being an aftereffect.
ContributorsMarino, Annette Webb (Author) / Glenberg, Arthur (Thesis director) / Presson, Clark (Committee member) / Blais, Chris (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Family influences are known predictors of adolescent health and well-being trajectories, yet little research has investigated how adolescents’ orientation to family may be associated with their physiological stress responses. Influenced by the strength-based approach to culture, this study evaluated 418 Hispanic adolescents' familism values and perceived life stress in family, school, and peer domains to investigate prospective associations with hypothalamic-pituitary-adrenal axis stress responses to the Group Public Speaking Task for Adolescents (GPST-A). Prior growth-mixture modeling on this sample revealed a five-class solution of cortisol responding to the GPST-A that was used here as the dependent variable: one class showed a more pronounced pattern of reactivity, potentially indicative of hyper-responsivity to the stress task; two classes showed evidence of a low to moderate cortisol response, potentially indicative of an adaptive physiological response to the challenge; and two classes showed patterns of non-responsivity, potentially indicative of hypo-responsivity. Results demonstrate that the role of familism is nuanced in the context of stressors, potentially offering both promotive and risk-amplifying effects for the physiological stress response system. This study offered several novel findings in the relation between cultural factors, salient stressors of adolescence, and HPA activity.
ContributorsSmola, Xochitl Arlene (Author) / Gonzales, Nancy (Thesis director) / Presson, Clark (Committee member) / Doane, Leah (Committee member) / Department of Psychology (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Substance use during adolescence is a significant predictor of developing a later substance use disorder. An encouraging trend is that there have been recent declines in rates of adolescent substance use, including alcohol and marijuana. However, these two substances may be decreasing differently from one another as a result of age, period, and cohort effects. Therefore, the overall trend of decreased substance use in more recent generations of adolescents may be greater for one substance than the other. The current study tested declines in adolescent alcohol and marijuana use across two generations measured in 1988-1990 and 2006-2012. Methodological strengths include controls for demographic characteristics and for parental alcohol disorder (as a proxy for genetic risk). Moreover, we tested whether findings would replicate using two methods—first comparing all assessed members of one generational cohort with all assessed members of the other generational cohort, and then comparing only matched parent-child pairs. Testing this second matched sample removes some potential demographic and risk confounds that might occur across cohorts in typical epidemiological studies. Results demonstrated that the younger cohort of adolescents used both substances less than the older cohort, and this effect was stronger for alcohol than for marijuana. These results were replicated in both samples over and above demographic variables. The parent-child sample showed that children used less alcohol and marijuana than did their parent during the same age period, suggesting that these trends cannot simply be due to changes in the demographics of the adolescent population over time. Taken together with epidemiological studies, these findings suggest encouraging declines in adolescent substance use rates but also indicate less decline in marijuana use compared to alcohol use. This prompts further surveillance to determine if marijuana use rates may start increasing among adolescents in the future.
ContributorsWatters, Shannon Marie (Author) / Chassin, Laurie (Thesis director) / Presson, Clark (Committee member) / Department of Psychology (Contributor) / School of Social Transformation (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05