Browsing by Subject "gait"
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Item APAL "Sensitivity to changes in dynamic affordances for walking on land and at sea" Data Sets(2019-09-17) Walter, Hannah; Li, Ruixuan; Peterson, Nicolette; Stoffregen, Thomas; Wagman, Jeffrey; walte666@umn.edu; Walter, Hannah; University of Minnesota Affordance Perception-Action LabWe investigated the perception of affordances for walking along a narrow path. We asked whether participants could perceive changes in affordances brought about by manipulation of properties of the body, or of the environment, without direct practice of the to-be-perceived affordance, and without external feedback about the accuracy of perception. In Experiment 1, participants made a series of 8 judgments of how far they could walk along a narrow path either, 1) without added weight, 2) while wearing a weighted vest, or 3) while wearing weights on their ankles. Before walking, mean judgments were lower when wearing weights than in the no-weight condition. In addition, in both weight conditions judgments changed across the series of 8 judgments, in the direction of greater accuracy. Control of the body in walking also can be influenced by motion of the ground surface, as commonly happens in vehicles. In Experiment 2, on a ship at sea, we evaluated the effects of walking with or without weight added to the body at the ankles. We again asked participants (experienced maritime crewmembers) to judge how far they could walk along a narrow path, with versus without ankle weights. As in Experiment 1, judgments made before walking mirrored the observed differences in walking performance. In addition, we again found evidence that judgment improved (without walking practice, or feedback) over the series of judgments. We conclude that participants were sensitive to (and spontaneously learned about) how affordances for walking were influenced by changes in the dynamics of body and the environment.Item Genetic Factors Underlying Disease and Performance Traits in Standardbreds(2014-05) McCoy, AnnetteMany diseases and performance characteristics of the horse are considered to be "complex" traits because they are influenced by both genetic and environmental factors. Furthermore, many are polygenic in nature, reflecting the combined effects of multiple genes. Traditional methodological approaches, such as family linkage analysis and candidate gene sequencing are not ideal for identifying the multiple interacting alleles underlying complex/polygenic traits. An alternative investigational approach is needed that can account for environmental risk factors, issues related to population structure in large study cohorts, and epistatic interactions. In the work presented here, whole-genome approaches, including genome-wide association (GWA) analysis, whole-genome sequencing (WGS), and high-throughput genotyping, were used to investigate the genetic factors underlying three complex traits in Standardbred horses, a breed primarily used for harness racing. These were 1) osteochondrosis (OC; a disease of young horses in which the cartilage at the end of long bones does not form normally); 2) pacing (an alternative pattern of locomotion); and 3) performance (using speed as the phenotype). GWA analysis identified chromosomal regions of association for all three traits of interest, although the significance of the findings for speed was marginal, reflecting the challenge of appropriately phenotyping a complex trait such as performance. WGS performed in eighteen horses identified thousands of variants within chromosomal regions of association identified for OC and pacing, of which a small fraction were predicted to have functional effect. These variants were prioritized and a subset was selected for high-throughput genotyping in the study cohorts (180 horse phenotyped for OC, 500 phenotyped for gait). A few of the markers selected for OC were moderately associated with disease status, while the majority of the markers selected for gait were highly associated with this trait. A crucial next step for interpreting these data will be trying to understand the potential interactions between markers, using a combination of pathway analysis and random forest analysis. Knowledge of gene variants that affect complex traits in the horse - and how they interact with each other - may help reduce the incidence of disease and assist selection for desirable characteristics.Item Investigating the effects of subthalamic nucleus stimulation on gait and pedunculopontine nucleus activity in a preclinical animal model of Parkinson’s disease(2022-02) Doyle, AlexandraDopamine-replacement therapy and deep brain stimulation therapy can reliably manage several cardinal motor signs of Parkinson’s disease including tremor, rigidity, and bradykinesia. The efficacy of these treatments on gait and postural dysfunction, however, are often variable and wane over time. This doctoral dissertation advanced our understanding of parkinsonian gait dysfunction by (1) defining spatiotemporal progression of gait changes with increasing parkinsonian severity in the MPTP non-human primate model of Parkinson’s disease, (2) characterizing changes in gait parameters with targeted subthalamic deep brain stimulation, and (3) defining how targeted subthalamic deep brain stimulation differentially affects neuronal spike rate and pattern changes in the pedunculopontine nucleus, which is a key structure in the mesencephalic locomotor region. The major findings were that the MPTP non-human primate model displays progressive bradykinetic gait that align with severity of other cardinal motor signs; however, asymmetric and disordered gait patterns only appeared in the more advanced parkinsonian state. Deep brain stimulation of the subthalamic nucleus showed a spatial map in of improving and worsening bradykinetic gait, and this map aligned with a differential effect on pedunculopontine nucleus modulation. These results suggest that deep brain stimulation can impart therapeutic effects on gait symptoms, but the effects depend on how one modulates pathways involved in locomotion. Such findings will be useful for future efforts to optimize deep brain stimulation for individuals with Parkinson’s disease.Item Nautical Affordances for Walking(2019-08) Walter, HannahI investigated the perception of affordance that emerge from dynamic aspects of humans (lateral oscillations of the body during walking) and the environment (angular motion of the ground). I chose to focus on the ways in which motion of ships at sea may influence how humans detect their affordances. Humans going out to sea for thousands of years, yet very little research has addressed perception and action at sea. I conducted several affordance experiments at sea to begin filling the large gap in human movement literature. I chose to investigate the affordance of walking on the deck within the confines of a pathway. In Experiment 1, I asked seasoned mariners to estimate their ability to walk within a set pathway. Upon completion of these judgments, the mariners were then asked to perform the walking task. The results showed that mariners’ judgments were accurate. In Experiment 2, I built off of this success, repeating the same design across daily changes in ship angular motion. Judgments accurately reflected these daily changes. Finally, in Experiments 3 and 4, I took a different approach. While the two previous experiments utilized the natural ship motion (environmental factor) to change the affordance, in Experiments 3 and 4 I used weights added to the participant (animal factor) to manipulate affordances for walking. I first established that added weight influenced affordance judgments on land. I then found similar effects on a ship at sea. Taken together, my experiments expand our understanding of perceptual sensitivity to affordances that arise from dynamic properties in the animal-environment system. Additionally, many implications concerning nautical performance and safety can be gleaned from this study.