Matching Items (2)
Description
The efficacy of deep brain stimulation (DBS) in Parkinson's disease (PD) has been convincingly demonstrated in studies that compare motor performance with and without stimulation, but characterization of performance at intermediate stimulation amplitudes has been limited. This study investigated the effects of changing DBS amplitude in order to assess dose-response characteristics, inter-subject variability, consistency of effect across outcome measures, and day-to-day variability. Eight subjects with PD and bilateral DBS systems were evaluated at their clinically determined stimulation (CDS) and at three reduced amplitude conditions: approximately 70%, 30%, and 0% of the CDS (MOD, LOW, and OFF, respectively). Overall symptom severity and performance on a battery of motor tasks - gait, postural control, single-joint flexion-extension, postural tremor, and tapping - were assessed at each condition using the motor section of the Unified Parkinson's Disease Rating Scale (UPDRS-III) and quantitative measures. Data were analyzed to determine whether subjects demonstrated a threshold response (one decrement in stimulation resulted in ≥ 70% of the maximum change) or a graded response to reduced stimulation. Day-to-day variability was assessed using the CDS data from the three testing sessions. Although the cohort as a whole demonstrated a graded response on several measures, there was high variability across subjects, with subsets exhibiting graded, threshold, or minimal responses. Some subjects experienced greater variability in their CDS performance across the three days than the change induced by reducing stimulation. For several tasks, a subset of subjects exhibited improved performance at one or more of the reduced conditions. Reducing stimulation did not affect all subjects equally, nor did it uniformly affect each subject's performance across tasks. These results indicate that altered recruitment of neural structures can differentially affect motor capabilities and demonstrate the need for clinical consideration of the effects on multiple symptoms across several days when selecting DBS parameters.
ContributorsConovaloff, Alison (Author) / Abbas, James (Thesis advisor) / Krishnamurthi, Narayanan (Committee member) / Mahant, Padma (Committee member) / Jung, Ranu (Committee member) / Helms Tillery, Stephen (Committee member) / Arizona State University (Publisher)
Created2013
Description
The benefits of exercise have been recommended in typical and other special populations. However, the evidence for persons with Down syndrome (DS) is still limited. This study was aimed at investigating the impact of an acute bout of aerobic exercise intervention on motor performance, executive function and intrinsic motivation in adolescents and young adults with DS. Ten participants with DS were assigned to an exercise group, who walked on a incremental treadmill protocol for 20 minutes. The exercise intensity was achieved at 66% of their predicted maximum heart rate. Another ten participants with DS were assigned to an attentional control group, who watched a video for 20 minutes. Measures of fine manual dexterity (e.g., Purdue Pegboard test), manual force production (e.g., grip strength test), processing speed (e.g., visual choice reaction time test), verbal processing (e.g., verbal fluency test), attention shifting ability (e.g., The Dimensional Card sorting test), and inhibitory control (e.g., Knock and Tap test) were tested pre and post intervention. An intrinsic motivation scale (e.g., enjoyment and effort) was conducted after the intervention. First, results showed participants significantly improved their performance in manual force production and Knock and Tap Test after the exercise intervention. While it has been proposed that exercise increases arousal status, neurotransmitters, or cerebral vasculature, the exact mechanisms in persons with DS are still unknown. However, our results showed that after treadmill walking, motor and cognitive improvements can be found in individuals with DS, even in a single exercise session. In addition, participants reported higher scores in enjoyment after video viewing than exercise, which may a result from musical effect or too much emphasis on external rewards in their early participation in exercise. These may imply that participants had low intrinsic motivation to an active lifestyle. Further, scores in effort were significantly higher after exercise than video viewing, which indicated their capabilities to perceive their physical exertion. However, other motivational regulations (e.g., introjected and identified regulations) have shown the relationship with exercise behavior in this population. Thus, further study should consider divergent motivational factors in order to implement an effective exercise program.
ContributorsChen, Chih-Chia (Author) / Ringenbach, Shannon D.R. (Thesis advisor) / Crews, Debra (Committee member) / Kulinna, Pamela (Committee member) / Amazeen, Eric (Committee member) / Arizona State University (Publisher)
Created2013