Doctor of Philosophy (PhD)
Medical Sciences Interdepartmental Area
Cerebral palsy (CP) is the most common neuromotor developmental diagnosis that can result in a myriad of activity impairments. The literature has primarily explored motor impairments in children with CP. Additionally, there is evidence of CP impacting several cognitive domains in children and adults with CP. Very little literature has explored if these impairments persist into adulthood, and the underlying neurophysiology serving these functions in individuals with CP is unknown.
The first purpose of this dissertation was to quantify the cortical oscillations serving hand movement with magnetoencephalography (MEG) and determine if differences were present as a function of age between children and adults with CP compared to an age-matched control group. The group with CP was slower to respond and less accurate compared to the controls. We found that the group with CP demonstrated a reduced beta response with age, while the control group had an increased response with age within the bilateral supplementary motor areas. Additionally, the motor hand “knob” area of the brain demonstrated a reduced beta response prior to movement onset in the group with CP. These divergent group finding may partially explain the movement performance deficits observed in this cohort.
Another aim of this dissertation was to explore cognitive impairments in individuals with CP. Two cognitive domains that are essential for daily function include selective attention and working memory (WM). We utilized MEG to investigate the neurophysiology underlying both of these cognitive domains. Therefore, the second purpose of this dissertation was to examine the neurophysiology underlying selective attention. For this study, individuals were shown a target stimulus with flanking stimuli surrounding the target. The surrounding stimuli were either the same as the target or different (more distracting). The group with CP was slower to respond to the target stimulus and was less accurate on their responses. The MEG results revealed there was a significant difference in the alpha response between groups in the primary visual cortices suggesting possible visual processing issues. Such visual processing issues could partially explain the poorer performance found in children and adults with CP. Secondly, there were similarities between the groups as a function of age. The alpha response was similarly activated in the left insula, and the theta response was similarly activated in the right insula across groups. These results imply that the insula (a region located within the ventral attention network (VAN)) is activated similarly as a function of age in both groups suggesting this attentional network may not have aberrant age-related activity in individuals with CP.
The third aim of this dissertation was to explore the neurophysiology underlying WM performance in adults with CP. Both groups completed a verbal WM task in which they had to report if a probe letter was included in the previous set of four letters while undergoing MEG. The MEG results showed a left-lateralized alpha-beta response during the encoding period within the occipital, temporal, and prefrontal cortices and an alpha response in the bilateral cortices during maintenance. The strength of the alpha-beta oscillations in the prefrontal cortices was weaker in the group with CP during encoding and associated with poorer performance on the NIH Toolbox. While activity during the maintenance period was similar between groups. Collectively, these results suggest that aberrations are present during the encoding time period, and they could partially explain poor cognitive performance in adults with CP.
Hoffman, Rashelle M., "The Neural Oscillatory Dynamics Underlying Motor and Cognitive Abilities in Children And Adults with Cerebral Palsy" (2020). Theses & Dissertations. 444.
Available for download on Thursday, April 28, 2022