Matching Items (3)
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- All Subjects: Brain--Concussion.
- All Subjects: Extinction (Psychology)
- Genre: Academic theses
- Creators: Smith, Brian
- Creators: Berg, Dena
Description
Concussion, a subset of mild traumatic brain injury (mTBI), has recently been brought to the forefront of the media due to a large lawsuit filed against the National Football League. Concussion resulting from injury varies in severity, duration, and type, based on many characteristics about the individual that research does not presently understand. Chronic fatigue, poor working memory, impaired self-awareness, and lack of attention to task are symptoms commonly present post-concussion. Currently, there is not a standard method of assessing concussion, nor is there a way to track an individual's recovery, resulting in misguided treatment for better prognosis. The aim of the following study was to determine patient specific higher-order cognitive processing deficits for clinical diagnosis and prognosis of concussion. Six individuals (N=6) were seen during the acute phase of concussion, two of whom were seen subsequently when their symptoms were deemed clinically resolved. Subjective information was collected from both the patient and from neurology testing. Each individual completed a task, in which they were presented with degraded speech, taxing their higher-order cognitive processing. Patient specific behavioral patterns are noted, creating a unique paradigm for mapping subjective and objective data for each patient's strategy to compensate for deficits and understand speech in a difficult listening situation. Keywords: concussion, cognitive processing
ContributorsBerg, Dena (Author) / Liss, Julie M (Committee member) / Azuma, Tamiko (Committee member) / Caviness, John (Committee member) / Arizona State University (Publisher)
Created2013
Description
The goal of the present study was to investigate whether a rest period following the end of chronic stress would impact fear extinction. Past research has indicated that chronic stress leads to impairments in the learning and recall of fear conditioning extinction. Moreover, the effects of chronic stress can return to levels similar to controls when a post-stress “rest” period (i.e., undisturbed except for normal husbandry) is given prior to testing. Male rats underwent chronic restraint stress for 6hr/day/21days (STR-IMM). Some rats, underwent a post-stress rest period for 6- or 3-weeks after the end of stress (STR-R6, STR-R3). Control (CON) rats were unrestrained for the duration of the experiment. In Experiment 1, following the stress or rest manipulation, all rats were acclimated to conditioning and extinction contexts, fear conditioned with 3 tone-foot shock pairings, and then had two days of extinction training. All groups froze similarly to the tone across all training sessions. However, STR-R6/R3 froze less in the non-shock context than did STR-IMM or CON. During extinction training, STR-IMM showed high levels of freezing to the non-shock context, leading to a concern they may be generalizing across contexts. Consequently, a follow-up experiment tested for context generalization. In Experiment 2, STR-IMM rats underwent a generalization test in an environment that was either different or the same as the conditioning environment, using STR-R6 as a comparison. STR-IMM and STR-R6 showed similar relative levels of freezing to tone and context, regardless of their conditioning environment to reveal that STR-IMM did not generalize and instead, maybe expressing hypervigilance. Thus, the present study demonstrated the novel finding that a rest period from chronic stress can lead to reduced fear responsiveness in a non-shock environment.
ContributorsJudd, Jessica M (Author) / Conrad, Cheryl D. (Thesis advisor) / Sanabria, Federico (Committee member) / Smith, Brian (Committee member) / Arizona State University (Publisher)
Created2018
Description
Traumatic brain injury (TBI) most frequently occurs in pediatric patients and remains a leading cause of childhood death and disability. Mild TBI (mTBI) accounts for 70-90% of all TBI cases, yet its neuropathophysiology is still poorly understood. While a single mTBI injury can lead to persistent deficits, repeat injuries increase the severity and duration of both acute symptoms and long term deficits. In this study, to model pediatric repetitive mTBI (rmTBI) we subjected unrestrained juvenile animals (post-natal day 20) to repeat weight drop impact. Animals were anesthetized and subjected to sham or rmTBI once per day for 5 days. At 14 days post injury (PID), magnetic resonance imaging (MRI) revealed that rmTBI animals displayed marked cortical atrophy and ventriculomegaly. Specifically, the thickness of the cortex was reduced up to 46% beneath and the ventricles increased up to 970% beneath the impact zone. Immunostaining with the neuron specific marker NeuN revealed an overall loss of neurons within the motor cortex but no change in neuronal density. Examination of intrinsic and synaptic properties of layer II/III pyramidal neurons revealed no significant difference between sham and rmTBI animals at rest or under convulsant challenge with the potassium channel blocker, 4-Aminophyridine. Overall, our findings indicate that the neuropathological changes reported after pediatric rmTBI can be effectively modeled by repeat weight drop in juvenile animals. Developing a better understanding of how rmTBI alters the pediatric brain may help improve patient care and direct "return to game" decision making in adolescents.
ContributorsGoddeyne, Corey (Author) / Anderson, Trent (Thesis advisor) / Smith, Brian (Committee member) / Kleim, Jeffrey (Committee member) / Arizona State University (Publisher)
Created2014