Investigation of MRI Brain Changes in Developmental Coordination Disorder and Friedreich’s Ataxia

Publish Year: 1397
نوع سند: مقاله کنفرانسی
زبان: English
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NSMED01_013

تاریخ نمایه سازی: 5 آذر 1397

Abstract:

To move things is all mankind can do. ... whether whispering a syllable or felling a forest.’ - Charles SherringtonThe human motor system is one of the most complicated systems in the human body. This complex system of interactions and collaborations between different regions of the human nervous system enables humans to interact with their external environment. Several parts of the human central nervous system are required to communicate effectively to send signals to the target muscles to carry out the final voluntary or involuntary movements. At the level of the central nervous system (CNS), motor planning and control form the essential element of any voluntary movements and several models have been suggested to describe these processes. Internal models, and specifically the ‘forward model’ is one of the most recognised theories of human motor control function. In this thesis, I have investigated two different movement disorders in which motor dysfunction is suggested to be involved in motor planning level in one disorder and motor execution in the other. I used several novel MRI methods to elucidate the neuro-mechanisms and brain regions likely to be involved in motor impairment in these two disorders, developmental coordination disorder (DCD) and (Freidreich’s ataxia) FRDA. Integral to this process was an endeavor to investigate human motor control theory and examine its pathological aspects through the window of neuroimaging.Recent advances in neuroimaging technologies, and particularly MRI methods, have provided researchers with invaluable insights into the structure of the human brain compared with those obtained by conventional T1 and T2 MRI imaging methods. I have used novel structural MRI technologies in this research project, including diffusion tensor imaging (DTI) and magnetisation transfer imaging (MTI). I have also harnessed the power of functional magnetic resonance imaging (fMRI), a method of mapping brain activity based on measuring the hemodynamic response related to neural activity. This method has received considerable attention in neuroscience studies because of its non-invasive nature and it offers the potential to map brain activities in considerably higher spatial resolution compared to older methods such as EEG. I have used these new functional and structural MRI imaging techniques to investigate the dysfunction in human motor execution and planning circuits in DCD and FRDA.Developmental Coordination Disorder (DCD) is a movement disorder with an unknown aetiology and a prevalence of 5-10% in children. Individuals with DCD show noticeable impairment in motor skills at both fine and gross levels. DCD is mostly diagnosed in children of school ages and there is up to a 50% chance that these symptoms continue into adulthood. There is some evidence that shows DCD is a motor imagery deficit. We investigated the neural basis of DCD using functional MRI whilst participants performed a mental rotation task. An analysis of pilot results supports the impairment of motor imagery ability in the expected areas in individuals with DCD. Using structural and functional MRI techniques we also investigated motor dysfunction in a second movement disorder, namely Friedreich’s ataxia (FRDA). FRDA is a genetic systemic disorder in which muscle weakness, ataxia and sensory loss are common neurological manifestations. To investigate the structural changes in the CNS of FRDA patients, we used the Magnetisation Transfer Imaging (MTI) technique. The results Neuroimaging studies of both DCD and FRDA are scare and as mentioned above, I have used different MRI modalities including microstructural and functional methods to investigate neural correlate and pathways characteristics and pathologies in DCD and FRDA. The results for individuals with DCD showed reduced cortical neural activation of grey matter during the performance of motor imagery task in the middle frontal gyrus bilaterally, the left superior parietal lobe and lobule VI of the cerebellum in adults with probable Developmental Coordination Disorder compared to control group. The individual with DCD compared with controls also showed a reduction in microstructural white matter in pathways including corticospinal tract, superior longitudinal fasciculus and internal capsule. There was also a tentative compensatory maturational compensation in inferior longitudinal fasciculus. The investigation of demyelination in Friedreich’s ataxia showed the presence of myelin bulk reduction in the superior cerebellar peduncle (SCP) region in patients suffering FRDA. The results of research presented in thesis are very promising in elucidating the physiopathology of neural damage and involved brain areas of above-mentioned disorders. In addition, the results emphasise the role of novel imaging technologies, such as MRI in the understanding both the theoretical aspects and practical application in individuals with motor dysfunction, especially in movement disorders such as DCD and FRDA in which conventional methods such as traditional imaging methods and laboratory biochemistry laboratory tests are of very limited value. This research also suggests that MRI findings could be considered as a potential biomarker for determining the severity of motor disorders, following up the clinical progression and evaluating the effectiveness of therapeutic interventions in movement disorders with neurological causes at CNS level

Authors

Saman Rassaei Kashuk

Victoria University College of Engineering and Science