Women with exercise associated amenorrhea display a disturbance in basal and exercise levels of reproductive, anti-reproductive and stress hormones. Co-incident with chronic exercise are other factors, which alone, also affect the menstrual cycle. Therefore, amenorrheic runners (AR), regularly menstruating runners (RMR) and regularly menstruating sedentary controls (RMSC) were compared for plasma progesterone levels, plasma lipid levels, menstrual cycle characteristics, physical characteristics and nutritional adequacy to determine if the difference in menstrual status could be explained, and to determine whether exercise alone could be attributed as the cause of menstrual cycle disturbances.Plasma progesterone levels were significantly lower in the AR group (. 28 + .02 ng/ml) than in the RMR group (.41 + .06 ng/ml) and the RMSC group (.49 + .06 ng/ml) in the follicular phase. Regularly menstruating runners demonstrated lower plasma progesterone levels in the luteal phase (9.76 + 1.05 ng/ml) than RMSC subjects (10.24 + 2.21 ng/ml). Regularly menstruating runners had a significantly shorter luteal phase length relative to their cycle length (.35 + .01) than RMSC subjects (.46 + .01). Mean age, incidence of parity, age of menarche, height, weight, body composition, max V02 and number of miles run per week did not differ between the RMR and AR subjects. Amenorrheic runners took in significantly less fat, red meat, phosphorous and total calories than the RMR subjects. Serum LDL-C was significantly higher in the AR subjects (89.2 + 9.7 mg/dl) than in the RMR subjects in both the luteal (67.8+ 3.4 mg/dl) and follicular (66.8+ 5.6 mg/dl) phases. Serum HDL-C was significantly higher in the RMR subjects in both the luteal (62.9+ 4.1 mg/dl) and follicular (59.2+ 2.9 mg/dl) phase, and in the AR subjects (63.9+ 4.2 mg/dl), than in the RMSC subjects in the luteal (49.2+ 5.9 mg/dl) and follicular (47.2+ 2.4 mg/dl) phase. Serum VLDL-C did not differ between any groups.This investigation demonstrates that hormonal and lipid level alterations with exercise are significantly different in the amenorrheic runner. However, regularly menstruating runners display alterations which may represent and intermediate or potential phase of menstrual cycle disturbances. The nutritional inadequacy or energy imbalance separates amenorrheic runners from regularly menstruating runners. Thus, it appears that exercise alone is not enough to cause the hormonal disturbances that trigger amenorrhea, and, that exercise associated amenorrhea is not unlike other amenorrheas of hypothalamic origin.

This dissertation presents results from three experiments to address two research questions: What do the acquisition and processing of information structure tell us about the acquisition and processing of language in general, and what do the acquisition and processing of information structure tell us about the nature of information structure as a syntactic and pragmatic phenomenon? The first two experiments were behavioral studies of native and L2 speakers of French in which subjects made acceptability judgments of sentences containing felicitous or infelicitous information structure. In Experiment 1, there was evidence of a postmaturational effect of age of arrival on judgment task scores; the geometry of this age effect did not show evidence of leveling off over time, contrary to the predictions of some formulations of the critical period hypothesis for second language acquisition (e.g. Newport, 1990; cf. Birdsong & Molis, 2001). The results of this experiment are interpreted as evidence against the presence of a critical period for the acquisition of information structure in a second language. In Experiment 2, L2 learners in low- and high-proficiency groups performed a similar judgment task. Low-proficiency L2 learners exhibited lower scores on the information structure anomaly judgment task than did high-proficiency L2 learners and L1 speakers. The behavioral results from this experiment, in conjunction with electrophysiological data from Experiment 3, suggest that many subjects judged the target sentences based on truth value, rather than information structure. In Experiment 3, subjects were presented with sentences containing felicitous and infelicitous information structure while a 14-channel electroencephalogram (EEG) was recorded. Results from this experiment suggest the presence of an N400 and P600 effect indexed with the processing of information structure anomalies in native-speaking subjects. L2 subjects of both high- and low-proficiency also exhibited a late positivity; however, results for the two groups diverged in the earlier time window, suggesting that high-proficiency speakers exhibit a P600 but low-proficiency speakers exhibit a P3 effect reflecting the processing of oddball stimuli. Taken together, the results from these experiments suggest that L2 speakers can acquire aspects of information structure processing to a nativelike degree. / text

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Clinical Psychology / Master / Master of Social Sciences

Exercise induced fatigue can have a negative impact on motor skill performance. While part of the decline is attributable to physiological factors that directly influence the coordination of movement, psychological factors may also contribute. Typically, motor learning environments encourage the accumulation of task-relevant declarative knowledge, which can be depended on to consciously support performance. The literature suggests that skills learnt in this way are vulnerable to demanding performance environments, including those in which the performer is fatigued. Recent empirical work has demonstrated that ‘implicit’ motor learning environments, devised to limit declarative knowledge buildup and/or dependence on working memory, promote resilient skill performance even after exhaustive fatigue protocols. Such findings imply that dependence on declarative knowledge to support motor skill execution may be a limiting factor under physiologically fatigue. However, it remains unclear the effect fatigue has on attentional resources, such as working memory. Using established experimental paradigms and EEG methodology, a research project was designed to investigate. Two explanations were considered: (1) fatigue distracts attention away from the control of movement or (2) fatigue directs attention to the skill, which interferes with automated control of the movement. In this study novice participants were allowed to freely accumulate declarative knowledge before completing a targeted muscle-fatigue protocol. A probe response paradigm assessed participants’ ability to recall the position of movement at the time a tone sounded, under the assumption that better recall reflects skill-focused attention. Neural activity was monitored by wireless EEG technology. Neural co-activation (or coherence) between brain regions associated with motor planning (Fz or F3) and with verbal-analytical processing (T3) has been suggested to reflect conscious control of motor skills. Therefore, a fatigue induced increase in T3-F3 coherence can be interpreted as increased conscious involvement in movement control, whereas, a decrease suggests a shift of attention away from movement control. The data collected suggests that to some extent fatigue raises visual-spatial and verbal-analytical contributions to motor control, but highlights methodological issues and limitations of the work. / published_or_final_version / Human Performance / Master / Master of Philosophy

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In man, tolerance to an orthostatic stress varies widely. Compensatory cardiovascular responses to orthostatic stressors such as head-up tilt, +Gz acceleration, and lower body negative pressure (LBNP) have been identified. However, physiologic reactions associated with the capacity to withstand a presyncopal- limited orthostatic exposure requires additional clarification. The relationship between maximal oxygen uptake (‘VO₂ max) and presyncopal-limited LBNP tolerance was examined in adult male subjects categorized into high (HAC) and low (LAC) aerobic capacity groups. In addition to similar (N.S.) cardiovascular responses, the (mean) and cumulative LBNP stress indices (CS)) observed in the HAC (722 torr•min) and LAC (784 torr•min) groups were also similar (N.S.). These data fail to support a relationship between LBNP tolerance and ‘VO₂ max. Cardiovascular responses associated with LBNP tolerance were measured during the control period (pre-LBNP) and final minute (peak LBNP) of decompression. The CSI criterion distinguished high (HT, n = 10) and low (LT, n = 8) LBNP tolerant groups was 640 torr•min. A greater (p < 0.05) end-diastolic volume and cardiac output was observed in the HT subjects during pre-LBNP may have provided a larger reserve to utilize throughout exposure to LBNP. At peak LBNP, both groups demonstrated similar (N.S.) cardiac outputs despite a higher (p < 0.05) HT heart rate. These data suggest that a major mechanism in prolonging LBNP tolerance may have been a greater LBNP-induced tachycardia. Blood samples were drawn to determine group differences in vasoactive neuroendocrine response. During peak LBNP, concentrations of norepinephrine increased (p < 0.05) in both groups. The HT group displayed greater (p < 0.05) LBNP-induced increases in vasopressin and plasma renin activity. These data suggest that HT subjects may have supplemented the catecholamine pressor response by involving the vasopressin and renin-angiotensin systems. The affect of cholenergic and beta-adrenergic blockades on cardiovascular responses to LBNP were examined in six HT and five LT subjects. CSI in both groups were unchanged (N.S.) by administration of atropine as compared to a placebo LBNP exposure. Propranolol however, reduced (p < 0.05) LBNP tolerance in both groups. This CSI reduction was greater (p < 0.05) in the HT subjects. The reduction in LBNP tolerance appeared closely associated with the negative chronotropic effect.

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