UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item Developing an Alternative Perspective on Coherence Seeking in Science Classrooms(2012) Sikorski, Tiffany-Rose; Hammer, David; Curriculum and Instruction; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Education research continues to struggle with how to characterize students' engagement in the doing of science. Too often, educators and researchers reduce doing science to learning particular facts and explanations, or participating in narrowly-defined, de-contextualized ways of reasoning and arguing. In this dissertation, I review prominent work that attempts to characterize students' engagement in one aspect of doing science--seeking coherence. By seeking coherence, I mean trying to make information "hang together" in meaningful, mutually consistent ways. Using examples from a variety of science classrooms, I show that these prominent approaches fail to provide substantive accounts of students' work to form connections between information. To address those weaknesses, I develop, refine and illustrate an alternative perspective on coherence seeking in science education, one that emphasizes what information students are trying to fit together, how they are trying to fit it together, and toward what ends.Item Arousal and skilled motor performance: The mediating role of cerebral cortical dynamics(2006-08-16) Rietschel, Jeremy Carl; Hatfield, Bradley D; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Despite achievement of a highly skilled level of motor competence, elucidation of the multiple factors contributing to variability of motor performance remains somewhat enigmatic. The inverted-U hypothesis posits moderate levels of arousal as essential to optimal performance; this suggests that arousal may be a key player of this variability. The purpose of this study was to examine the psychophysiological concomitants of moderate as compared to low arousal. Specifically we hypothesized a decrease in coherence between the temporal lobes (T3-verbal-analytical processing & T4-visuo-spatial processing) and the motor planning region (Fz), accompanied by an increase in task performance. Fifteen college undergraduates (9 females, 6 males, mean age = 23.4, SD = 4.22) participated in two days of testing. Day one consisted of 340 trials of a novel visuomotor pointing task to achieve task competency. On the second day, EEG data were recorded during both a Performance Alone (PA) condition vs. a Social-Evaluation and Competition (SE&C) condition, which were counterbalanced. Coherence estimates were subjected to a 2 x 2 ANOVA comparing Condition x Hemisphere; post hoc testing was completed using paired-t tests. The arousal-manipulation check of the two experimental protocols (PA vs. SE&C) provided by the autonomic measures and self-reports indicated an increase from a low to moderate level of arousal during the SE&C condition. There was a statistical interaction between condition and hemisphere revealing reduced coherence during SE&C only between T4-Fz (t(14) = 3.084, p = 0.008). Additionally, there was a increase in motor performance (t(13) = 2.171, p = 0.049). Consistent with the inverted-U hypothesis and our predictions as stated for moderate arousal relative to performing alone, there was a subsequent increase in performance coupled with a decrease in coherence between the visuo-spatial and the motor-planning regions. In light of the significantly improved kinematics, the reduction in networking between these task relevant areas is seen as an adaptive refinement of cortico-cortical communication as one moves from low towards optimal arousal.Item Role of Human Parietal and Premotor Cortical Areas in Complex Hand Movements(2005-04-11) Wheaton, Lewis A; Cohen, Avis; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The need to understand our ability to plan and successfully execute movement is a core aspect of clinical neurophysiology. Studies in humans are particularly valuable and can have direct application to neurological disorders. While most studies have focused on the physiological characteristics of relatively simple movements (e.g., finger flexion, extension), the aim of the current studies is to determine the mechanisms involved in producing meaningful, complex movements that better represent natural movements. Electroencephalography (EEG) measures such as movement-related cortical potentials, coherence, and event-related synchronization and desynchronization allow investigators to determine the functions of specific areas and coherent networks before and during movement. Patients with ideomotor apraxia, who produce abnormal movements with spatial and/or temporal errors during pantomime of praxis movements (e.g., using a hammer, waving good-bye), were compared to normal subjects. It is our hypothesis that performance of complex movements involves early preparatory activity seen localized in the left parietal and premotor cortical areas. Additionally, we hypothesize that the activity seen in the parietal and premotor cortices is coherent and part of a functional network for such movements. Stroke patients with parietal and premotor lesions with apraxia will show a decrease in function of these areas, as well as reduced communication of the network as a result of their anatomical damage. Our studies revealed widespread and early activity of the parietal cortex for praxis movements in normal subjects. This early activity was also seen in the inferior temporal cortex. The distribution and timing of this activity was different when comparing it to simple movements, which generally had activity confined to the premotor cortex. Moreover, an active functional network was seen between the parietal and premotor cortices of the left hemisphere for praxis movements. This network differed from that seen in patients with ideomotor apraxia, where activity in the right hemisphere parietal and premotor areas became predominant. These studies provide evidence of distinct and early parietal activity before praxis and a functional network that is involved in planning and execution, which can be modified in the event of brain injury.