Effects of dance therapy on balance, gait and neuro-psychological performances in patients with Parkinson's disease and postural instability

Postural Instability (PI) is a core feature of Parkinson’s Disease (PD) and a major cause of falls and disabilities. Impairment of executive functions has been called as an aggravating factor on motor performances. Dance therapy has been shown effective for improving gait and has been suggested as an alternative rehabilitative method. To evaluate gait performance, spatial-temporal (S-T) gait parameters and cognitive performances in a cohort of patients with PD and PI modifications in balance after a cycle of dance therapy

A multimodal approach to investigate brain reorganization after spinal cord injury using functional magnetic resonance imaging and functional near-infrared spectroscopy

Traumatic Spinal Cord Injury (SCI) results in structural and functional neurological changes at both the brain and the level of the spinal cord. Anatomical studies indicate decreased grey matter volume in sensorimotor and non-sensorimotor regions of the cortex following SCI; whereas, neurophysiological findings mostly report altered functional activity in the sensorimotor nodes of the cortex, subcortex, and cerebellum. Therefore, it is currently unknown whether tissue atrophy observed in non-motor related areas has any concomitant functional consequences. Furthermore, the neural underpinnings of adaptive neuroplasticity after SCI is not well-defined in the current literature. Hence, this dissertation is a pioneer study investigating the structural and functional changes in the whole brain after SCI, with particular focus on subcortical regions, using a multimodal approach employing magnetic resonance imaging (MRI), resting-state functional MRI (fMRI) and functional near-infrared spectroscopy (fNIRS), that may take best advantage of each of these three tools. MRI scans from 23 healthy controls (HC) and 36 individuals with complete SCI within two years of injury were used to demonstrate that both injury level and duration since injury are important factors contributing to recovery. Specifically, cervical level injury when compared to thoracolumbar level injury exhibits a greater loss of cortical grey matter volume in the orbitofrontal cortex, insula, and anterior cingulate cortex. Next, using the fMRI scans of the same participants during a resting-state scan, the intrinsic functional connectivity of the mediodorsal, pulvinar and ventrolateral nuclei of the thalamus to the regions of salient network and the fronto-parietal network is observed to be dynamic and altered in the SCI group. Lastly, a continuous-wave fNIRS is used to reliably measure brain function in individuals with SCI during both dynamic and static tasks while accounting for cerebrovascular reactivity. Five min of resting-state data and 26 min of motor data including finger tapping, finger tapping imagery and ankle tapping were acquired to identify the spatial activation pattern unique to each of the movement type. A breath-hold paradigm is also used to quantify cerebrovascular reactivity as a means to calibrate task activity from neurovascular constraints. Sixteen HC were scanned at two separate visits to determine the sensitivity and test-retest reliability of fNIRS data from the sensorimotor cortex. Following validation, the same procedure was repeated in 13 individuals with paraplegia resulting from SCI and 13 HC to quantify alterations in the cortical activity of the motor cortex and cerebrovascular reactivity between the two groups. Results indicate that SCI group exhibit altered cerebrovascular reactivity with greater delay in response and greater pre-stimulus undershoot. As hypothesized, the hemodynamic response to ankle movement resulted in only a small change in oxyhemoglobin concentration in the sensorimotor cortex of SCI group when compared to HC. The application of fNIRS to assess cortical reorganization following SCI is unique and expands our understanding of the neurophysiology after SCI. It paves the groundwork for extending the implementation of fNIRS to rehabilitation research and other clinical populations with vascular dysfunction. This dissertation is one of the first studies to comprehensively examine both the structural and functional alterations of the brain in humans with complete SCI and opens promising avenues for SCI research using fNIRS modality

Corticospinal excitability, mental rotation task, motor performance and disability in subjects with musculoskeletal disorders of the wrist and hand

L'objectif de cette thèse était de démontrer la présence de modifications des processus sensorimoteurs du système nerveux central (excitabilité corticospinale et schéma corporel tels que mesurés avec la Tâche de Reconnaissance de la Latéralité des Images droite gauche (TRLI)) chez des participants ayant des désordres musculosquelettiques au poignet et à la main. Un deuxième objectif était de déterminer la relation entre les changements de ces processus sensorimoteurs corticaux et des mesures sensorielles, de la fonction motrice, d'incapacité autodéclarée, de la douleur et des facteurs psychosociaux liés à la douleur. Une étude observationnelle transversale a d'abord été menée pour mesurer l'excitabilité corticospinale des muscles de la main en utilisant la stimulation magnétique transcrânienne et la TRLI chez des participants en santé et des participants présentant des douleurs chroniques au poignet et à la main. L’excitabilité corticospinale du muscle court abducteur du pouce de la main affectée était augmentée chez les participants présentant une douleur chronique et ces changements étaient significativement corrélés avec l'intensité de la douleur, l'incapacité autodéclarée, et négativement corrélés avec l'excitabilité motoneuronale. Des différences de performances sur le TRLI, à la fois pour la précision et le temps de réaction, ont également été trouvées entre les participants du groupe contrôle et les participants avec douleur. Dans une deuxième étude transversale, le TRLI, des mesures de motricité, sensibilité et des fonctions cognitives ont été administrées à soixante et un participants présentant des désordres musculosquelettiques du poignet ou de la main droite. Les modèles de régression linéaire multiple ont révélé que la prise de médicaments pour contrer la douleur, la participation à des activités (sociales, professionnelles, domestiques et récréatives), la discrimination tactile de deux points et le niveau de performance motrice expliquent les performances au TRLI. Les participants ayant pris des médicaments pour la douleur la journée de l’évaluation avaient une performance diminuée sur la précision et le temps de réaction sur le TRLI pour la main droite (affectée). Ces participants présentaient aussi une sévérité de douleur et d'incapacité plus élevée et une diminution de fonctions cognitives et motrices plus élevée que le reste des participants avec douleur qui ont été évalués. Dans l’ensemble, ces résultats suggèrent que les participants présentant des désordres musculosquelettiques hétérogènes du poignet ou de la main montrent des changements des processus sensorimoteurs corticaux. Alors que l'excitabilité corticospinale semble être liée à l'intensité de la douleur et à l’incapacité autodéclarée, le TRLI peut être associé à une confluence de facteurs (sensoriels, moteurs, cognitifs-affectifs et comportementaux). Ces résultats suggèrent aussi que les changements sensorimoteurs corticaux ne sont pas simplement le résultat du désordre musculosquelettique, mais impliquent plutôt une interaction complexe entre la douleur, les processus sensorimoteurs et cognitivo-affectifs, et peut-être aussi des réponses comportementales à l’atteinte musculosquelettique. Les résultats fournissent également des informations précieuses à propos des personnes qui pourraient bénéficier d'interventions orientées vers le rétablissement des processus centraux en plus des traitements de réadaptation axés sur les structures périphériques.The objective of the thesis was to investigate for the presence of changes in cortical sensorimotor processes (corticospinal excitability and the body schema measured with the Left Right Judgment Task (LRJT) performance), in participants with Musculoskeletal Disorders (MSD) of the wrist/hand. A second objective was to determine the relationship between these cortical sensorimotor processes and measures of sensory and hand motor function, disability, pain and pain related psychosocial factors. First, an observational cross-sectional study was conducted to explore corticospinal excitability of muscles in the hand and cortical sensorimotor processes, utilizing transcranial magnetic stimulation and the LRJT in healthy, pain-free participants and participants with chronic wrist/hand pain. Increased corticospinal excitability for the abductor pollicis brevis of the affected hand in participants with chronic MSD of the wrist/hand was found and these changes were significantly correlated with pain intensity, disability, and negatively correlated with spinal motoneuronal excitability. Differences in LRJT performance were also found between healthy control participants and participants with pain for both LRJT accuracy and reaction time. In a second cross-sectional study, LRJT performance, motor, sensory and cognitive assessments were performed on sixty-one participants with MSD of the right dominant wrist/hand. The multiple linear regression model revealed that taking pain medication, participating in (social, work, household and leisure) activities, two-point discrimination, and motor performance explained performance on the LRJT of the right (affected) hand. Those participants that took pain medication on the day of the evaluation performed more poorly on both LRJT accuracy and reaction time of the right (affected) hand. These participants had higher pain severity and disability scores and decreased cognitive and motor function. Collectively, these results suggest that participants with heterogeneous MSD of the wrist/hand display altered cortical sensorimotor processes. Whereas corticospinal excitability appears to be related to pain intensity and disability, the LRJT may be associated with a confluence of factors (sensory, motor, cognitive-affective, and behaviours). These findings suggest that cortical sensorimotor changes do not simply appear to be the result of the condition but involve a complex interaction between pain, sensorimotor and cognitive-affective processes, and possibly behavioural responses to the condition. The findings also provide valuable insight as to those persons who may benefit from cognitively directed interventions in addition to peripherally driven rehabilitative treatments

Does stroke location predict walk speed response to gait rehabilitation?

Objectives Recovery of independent ambulation after stroke is a major goal. However, which rehabilitation regimen best benefits each individual is unknown and decisions are currently made on a subjective basis. Predictors of response to specific therapies would guide the type of therapy most appropriate for each patient. Although lesion topography is a strong predictor of upper limb response, walking involves more distributed functions. Earlier studies that assessed the cortico-spinal tract (CST) were negative, suggesting other structures may be important. Experimental Design: The relationship between lesion topography and response of walking speed to standard rehabilitation was assessed in 50 adult-onset patients using both volumetric measurement of CST lesion load and voxel-based lesion–symptom mapping (VLSM) to assess non-CST structures. Two functional mobility scales, the functional ambulation category (FAC) and the modified rivermead mobility index (MRMI) were also administered. Performance measures were obtained both at entry into the study (3–42 days post-stroke) and at the end of a 6-week course of therapy. Baseline score, age, time since stroke onset and white matter hyperintensities score were included as nuisance covariates in regression models. Principal Observations: CST damage independently predicted response to therapy for FAC and MRMI, but not for walk speed. However, using VLSM the latter was predicted by damage to the putamen, insula, external capsule and neighbouring white matter. Conclusions Walk speed response to rehabilitation was affected by damage involving the putamen and neighbouring structures but not the CST, while the latter had modest but significant impact on everyday functions of general mobility and gait

Motor control drives visual bodily judgements

The ‘embodied cognition’ framework proposes that our motor repertoire shapes visual perception and cognition. But recent studies showing normal visual body representation in individuals born without hands challenges the contribution of motor control on visual body representation. Here, we studied hand laterality judgements in three groups with fundamentally different visual and motor hand experiences: two-handed controls, one-handers born without a hand (congenital one-handers) and one-handers with an acquired amputation (amputees). Congenital one-handers, lacking both motor and first-person visual information of their missing hand, diverged in their performance from the other groups, exhibiting more errors for their intact hand and slower reaction-times for challenging hand postures. Amputees, who have lingering non-visual motor control of their missing (phantom) hand, performed the task similarly to controls. Amputees’ reaction-times for visual laterality judgements correlated positively with their phantom hand’s motor control, such that deteriorated motor control associated with slower visual laterality judgements. Finally, we have implemented a computational simulation to describe how a mechanism that utilises a single hand representation in congenital one-handers as opposed to two in controls, could replicate our empirical results. Together, our findings demonstrate that motor control is a driver in making visual bodily judgments

Comparison of Brain Activation during Motor Imagery and Motor Movement Using fNIRS

Motor-activity-related mental tasks are widely adopted for brain-computer interfaces (BCIs) as they are a natural extension of movement intention, requiring no training to evoke brain activity. The ideal BCI aims to eliminate neuromuscular movement, making motor imagery tasks, or imagined actions with no muscle movement, good candidates. This study explores cortical activation differences between motor imagery and motor execution for both upper and lower limbs using functional near-infrared spectroscopy (fNIRS). Four simple finger- or toe-tapping tasks (left hand, right hand, left foot, and right foot) were performed with both motor imagery and motor execution and compared to resting state. Significant activation was found during all four motor imagery tasks, indicating that they can be detected via fNIRS. Motor execution produced higher activation levels, a faster response, and a different spatial distribution compared to motor imagery, which should be taken into account when designing an imagery-based BCI. When comparing left versus right, upper limb tasks are the most clearly distinguishable, particularly during motor execution. Left and right lower limb activation patterns were found to be highly similar during both imagery and execution, indicating that higher resolution imaging, advanced signal processing, or improved subject training may be required to reliably distinguish them