Human Physiology Theses and Dissertations

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Browsing Human Physiology Theses and Dissertations by Subject "Attention"

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    Attention and gait performance following a concussion
    (University of Oregon, 2008-06) Catena, Robert David, 1981-
    Currently the information on attention-balance control interactions following concussion is incomplete and not given particular consideration during clinical examinations of concussion. The purposes of this dissertation were to (1) test different gait paradigms for their sensitivity of identifying concussion symptoms and to (2) test how individual components of attention interact with gait performance. The long-term goal of this study is to establish more functional and succinct protocols for return-to-play decisions. Grade II (AAN guidelines) concussed individuals were recruited to participate in testing at 2, 6, 14, and 28 days post-injury. Gait and components of attention were analyzed during each session through a number of different paradigms. Control subjects were matched by stature, age, and athletic participation. The results indicate that the dynamic balance deficits following a concussion are immediately identified with an attention dividing gait task. Obstacle crossing identified more conservative adaptations 2 weeks after injury. A task combining the two did not clearly identify concussion deficits. Two components of attention showed promise as interacting with gait to cause balance deficits. The spatial orientation component showed an interaction with obstacle avoidance indicating that the same concussed individuals that had poor spatial orientation of attention also came closer to hitting the obstacle during crossings. An analysis of divided attention showed that concussed individuals performing poorly in one task also performed poorly in the other during a dual-task paradigm, but during any one particular trial there was a trade-off between task performances, which was not present in control individuals. The findings of this dissertation point to the use of a divided attention task to distinguish concussed individuals from healthy individuals immediately after a possible injurious event. How several different components of attention interact with gait performance is identified. Finally, if a concussion has occurred, an obstacle crossing task might be suitable for a long-term analysis of full recovery of balance control. Ultimately, it is my hope that the information provided here will lead to functionally relevant and clinically executable tests of concussed individuals before they are placed in harm's way due purely to an incomplete diagnosis of their injuries.
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    Effects of meditation training on attentional networks: A randomized controlled trial examining psychometric and electro-physiological (EEG) measures
    (University of Oregon, 2007-12) Joshi, Aditi A.
    Meditation has been defined as a "group of practices that self-regulate the body and mind, thereby affecting mental events by engaging a specific attentional set" (Cahn & Polich, 2006). We conducted a randomized, longitudinal trial to examine the effects of concentrative meditation training (40 min/day, 5 days/week for 8 weeks) on top-down, voluntary control of attention with a progressive muscle relaxation training group as a control. To determine if training produced changes in attentional network efficiency we compared, pre- and post-training, mean validity effect scores (difference between invalid cue and center cue reaction time) in the contingent capture paradigm (Folk et al., 1992). The meditation group showed a trend towards improvement of top-down attention while the relaxation group did not. Using EEG we assessed the changes in amplitudes of wavelets during periods of mind-wandering and meditation. Periods in which subjects were on- vs. off-focus during the meditation task were identified by asking subjects to make button presses whenever the mind wandered and also at probe tones, if they were off-focus. After training, the episodes of mind-wandering were significantly lower in the meditation group as compared to the relaxation group. Increased amplitudes of alpha and theta EEG frequencies in the occipital and right parietal areas were seen during the meditation task for the meditation but not the relaxation group as an effect of training. A baseline EEG trait effect of reduced mental activity was seen (meditation training: occipital and right parietal areas; relaxation training: only occipital areas). Within a given meditation session, prior to training, alpha and theta activity was lower in on-focus conditions (occurring immediately after subjects discovered they were off-focus and returned to active focus on the breath/syllable) compared to meditative focus segments. After training, we found higher alpha amplitude in periods of meditative focus as compared to periods of mind wandering for both groups. However, the meditation group showed significantly higher theta amplitude than the relaxation group during the meditative state segments.
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    Evaluation of Neuropsychological and Attentional Disturbances in Concussed High School Athletes
    (University of Oregon, 2011-06) Howell, David Robert, 1986-
    Approximately 1.5 million concussions occur annually in the United States, many affecting individuals between the ages of 15 and 18. Little is known about this age group's response to a concussion as they have been thought to respond differently than adults due to immature brain development. Additionally, relying on symptoms alone to determine level of brain function may lead to early return back to sport participation. Through the use of 3 computerized tests, neuropsychological and attentional deficit recovery post concussion was assessed between 12 subjects with concussions and 12 controls up to 2 months after injury. Memory tasks and symptoms resolved within a week after injury. Executive function tests showed small group differences up to two months post injury, suggesting these types of tests may be a useful tool in the evaluation of concussion recovery and provide an objective measure in evaluation.
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    The Role of Attention in Fall Avoidance: Evaluation of Dual Task Interference with Postural and Visual Working Memory Tasks in Young Versus Older Adults, Does Capacity Limitation Influence Postural Responses?
    (University of Oregon, 2013-07-11) Little, Carrie; Woollacott, Marjorie
    The primary goal of this research was to explore attentional factors contributing to normal balance control and to determine how age-related changes in these factors constrain balance in the aging adult. Though previous research has demonstrated attentional interference between postural control and performance of cognitive tasks in young (YA) and older adults (OA), the mechanisms contributing to interference have not been identified. This study utilized as a cognitive task, a visual working memory task (the change detection task), which identified the short term working memory (or attentional) capacity limits of participants. Participants were asked to perform the cognitive task (determining a change in the color of squares in a first vs. second memory array) either in isolation or with postural tasks of increasing complexity, including quiet sitting (control), quiet stance in isolation, quiet stance (but intermixed with support surface perturbations), and support surface perturbations. YA showed a significant decline in working memory capacity between the control and perturbation condition (p<0.01) but no change in postural performance between single and dual task conditions, as determined by increased steps in response to perturbations (p<0.33). In a second set of experiments, the performance of OA was compared to YA. Results showed that OA had reduced working memory capacity on the change detection task compared to YA even in the control condition (YA: 2.8±0.6 items; OA: 1.8±0.7; p<0.001). OA showed an even greater decline than YA in memory capacity in the dual task condition (p<0.001), along with difficulty regaining balance following perturbations, evidenced by significant increases in up on toes (p<0.05) and stepping strategies (p<0.05). These results suggest that visual working memory (for simple features) and postural control share a common attentional resource that is limited and that postural control is favored over the cognitive task in YA. In OA, attentional capacity was significantly reduced and both postural and cognitive tasks were impaired in the dual task condition, suggesting that with aging even simple cognitive tasks can negatively affect balance under challenging postural conditions.