The remapping of cortical networks after stroke is hypothesized to be one of the mechanisms subserving functional recovery. Our understanding of cortical remapping remains limited due to the inability to resolve which cells are active while performing motor tasks with high temporal and spatial specificity. The experiments presented in the first chapter of this thesis evaluate the ability of the inducible Arc-CreERT2:Rosa-YFPf/f model to label cells in the motor cortex activated by a motor-related behaviour. Through the modification of previously published 4-hydroxytamoxifen treatment paradigms, this model can differentiate between animals that performed the rotarod task at two time points and home cage controls. In addition, 65% of cells active at the first behavioural time point are reactivated. Taken together, these data suggest that the Arc-CreERT2:Rosa-YFPf/f model is able to reliably label networks used to perform the same behavioural task at two time points. The second chapter of this thesis details a pilot study in which the Arc-CreERT2:Rosa-ChR2:YFPf/f model was used to test the effect of daily optogenetic stimulation of the contralateral cortex on functional recovery. The results of this chapter suggest that stimulating the contralesional motor cortex may impair functional recovery. Overall, the results of this thesis lay the foundation to use this model to investigate motor networks in both naïve and pathological conditions, such as stroke.

In the absence of treatment following strokes, both humans and model organisms demonstrate partial improvements in motor function. Several endogenous mechanisms, such as cortical reorganization, are hypothesized to cause this spontaneous biological recovery. Reorganization of the motor cortex occurs within a time sensitive period and involves both proximal and distal sites of the intact brain. Despite these advancements, whether the same or different cells are used in the reorganized cortex after stroke remains unknown. In order to identify the motor networks involved in recovery, our lab has begun using the inducible Arc-CreERᵀ²:Rosa-YFPᶠᐟᶠ mice. In conjunction with the bimanual string-pulling task, this inducible model allows for the labelling of active cells throughout stroke recovery; either pre, 2 days post-stroke (dps) and 2 weeks post-stroke (wps). Behavioural deficits on the string-pull task were observed at 2 dps and accompanied by a decrease in active cells in the ipsilesional secondary motor (M2) cortex of stroke mice. By 2 wps, stroke mice had partial recovery of motor function with no differences in active cells in the ipsilesional M2. Interestingly, ~40% of cell in the motor cortex of sham and stroke mice were activated more than once while performing the string-pull task until 2 wps. Deeplabcut kinematic analysis of the string-pull task was also unable to identify differences in motor performance between stroke and sham mice. In addition, irrelevant of stroke injuries, only 60% of cells co-expressed the pan-neuronal marker NeuN after surgeries. Together these findings suggest that 40% of cells are reactivated up to 2 weeks post-stroke during the performance of a motor task, despite the acute decreases in active cells in the ipsilesional M2 of stroke mice. DeepLabCut kinematic results also highlight the need to redefine kinematic outcomes to better assess the full spectrum of stroke deficits.

This study evaluated whether cortical reorganization occurs in response to macular degeneration (MD), a progressive disorder of the retina that results in central vision loss. Past research has observed the ability of V1 to adapt to retinal damage, demonstrating that deafferented cortex is activated by the stimulation of intact retinal areas. It is still unclear, however, if and to what degree cortical reorganization is associated with specific forms of macular degeneration. This study evaluated the retinal health of MD participants (both age-related and juvenile) as well age-matched controls with computerized microperimetry. Contrast-reversing stimuli were then presented to different parts of the visual field while participants were scanned with functional magnetic resonance imaging (fMRI). For MD participants, stimulation of peripheral retinal areas elicited activation in deafferented cortex. This activation occurred for retinal areas adapted for eccentric viewing (preferred retinal locations), but not in preserved retina at the same eccentricity. These findings add to the scientific knowledge of plasticity in sensory systems by supporting an experience driven understanding of cortical reorganization. They could also have a meaningful impact on how macular degeneration is treated by informing the design of therapeutic training regimes.

<p>Abstract</p><p>This essay examines which role functional oriented music therapy, which is supposed to help sensorimotor development, can have in schools and in health care. To find this out, research about what kinds of effects exercise can have on academic achievements and in recovery from brain injuries has been brought up. The research concerning academic achievements was conducted with school children; some children without difficulties, some with sensory integration problems, and some with motor skill difficulties. In addition to this, research about the brain structure superior colliculus, which lies behind sensory integration, is also brought up.</p><p>The results showed that children who were given more exercise had significantly better scores in academic skills than the children with normal academic education. Thus, it might be reasonable to practise functional oriented music therapy in schools, both as helping general development, but also for children with different types of difficulties.</p><p>The research concerning exercise and injuries has made clear that the adult brain can change via neurogenesis, plasticity and cortical reorganization. These three aspects are important when practicing a skill or when recovering from an injury. Exercise has been shown to affect these three aspects positively and can therefore also aid the recovery from injuries.</p><p>Thus, there seems to be many theoretical aspects supporting the FMT- method. However, the question is if the results of one treatment form can generalize over such a wide range of injuries and defects that the FMT –adepts usually have. It is therefore also discussed if further experiments on the FMT-method could help make it a more effective tool for rehabilitation.</p>

Deafness affects approximately 40 million people in the United States. However, little is known about how the brain reorganizes itself in response to this major loss of inputs. Preliminary studies of neonatally deafened cats reveals that the auditory cortical area, the auditory field of the anterior ectosylvian sulcus (FAES), is reorganized as a visual area and is involved in the control of visual orientation behaviors. The plastic changes in neuronal connectivity that underlie this cortical reorganization are not known, but it is our hypothesis that sensory driving via thalamocortical inputs must change from auditory to visual thalamic origins. The present study used neuroanatomical tracing techniques in two hearing adult cats and two adult cats deafened at birth to determine the thalamic origin of projections to the FAES. When tracer was injected into the FAES of hearing animals, MGm, MGv, Pom, and dorsal thalamic nuclei showed retrogradely labeled cell bodies indicative of their projection to the FAES. When tracer was injected into the FAES of the neonatally deafened animals, MGm, MGv, Sgl, Pom, and dorsal thalamic nuclei also showed retrogradely labeled cells. In the deafened animals, no retrogradely labeled neurons were identified in the primary visual thalamic areas. Because essentially the same thalamic regions project to the FAES but relay different sensory messages in hearing and deafened animals, it must be concluded that neuronal plasticity occurred prior to the thalamocorticals projection. Therefore, therapeutic efforts to ameliorate the effects of deafness might best address thalamic rather than cortical mechanisms of plasticity and neuronal reorganization.

The extent to which cortical maps may reorganize in adult humans is a significant and topical debate in visual neuroscience. Though there are conflicting findings, evidence from humans and animals indicates that the topography of the visual cortex may change after retinal deafferentation. Remarkably, this reorganization seems to be possible in adults, whose brains are less amenable to plastic change. If adult visual reorganization is legitimate, an understanding of its causes and consequences could be profound considering the millions suffering from age-related visual disorders. This dissertation explores whether visual training may yield a reorganization of sensory maps in the adult visual cortex. It describes research in which patients, diagnosed with age-related macular degeneration (AMD), underwent visual rehabilitation therapy. Functional brain scans and behavioral tests were conducted pre and post training. These interventions generated valuable knowledge regarding whether "reorganized" activity is a true rewiring of feed forward cortical processes or an artifact of attentional feedback. The rehabilitation training produced demonstrable differences in activation patterns along the primary visual cortex (V1), but sparse improvement in the behavioral tests. In contrast, there was significant improvement in fixation tests which assessed oculomotor control. These results suggest that the nature of reorganized activity has more to do with attentional mechanisms than feed forward reorganization. Future investigations could benefit from examining the brain sites that govern visual attention in the frontal and parietal cortices. These areas may have more to do with visual adaptation in AMD patients than V1.

Abstract This essay examines which role functional oriented music therapy, which is supposed to help sensorimotor development, can have in schools and in health care. To find this out, research about what kinds of effects exercise can have on academic achievements and in recovery from brain injuries has been brought up. The research concerning academic achievements was conducted with school children; some children without difficulties, some with sensory integration problems, and some with motor skill difficulties. In addition to this, research about the brain structure superior colliculus, which lies behind sensory integration, is also brought up. The results showed that children who were given more exercise had significantly better scores in academic skills than the children with normal academic education. Thus, it might be reasonable to practise functional oriented music therapy in schools, both as helping general development, but also for children with different types of difficulties. The research concerning exercise and injuries has made clear that the adult brain can change via neurogenesis, plasticity and cortical reorganization. These three aspects are important when practicing a skill or when recovering from an injury. Exercise has been shown to affect these three aspects positively and can therefore also aid the recovery from injuries. Thus, there seems to be many theoretical aspects supporting the FMT- method. However, the question is if the results of one treatment form can generalize over such a wide range of injuries and defects that the FMT –adepts usually have. It is therefore also discussed if further experiments on the FMT-method could help make it a more effective tool for rehabilitation.

A lesão medular (LM) promove uma condição devastadora que resulta em comprometimentos sensorial e motor, impedindo o desempenho funcional do indivíduo. O entendimento sobre os mecanismos envolvidos na reorganização cortical após uma eficiente estratégia terapêutica pode fornecer informações relevantes para o aprimoramento de tecnologias assistivas, como neuropróteses. Este trabalho teve como objetivos investigar as alterações funcionais e estruturais no córtex sensório-motor de ratos Wistar submetidos à atividade física na esteira após a lesão medular contusa. O objetivo secundário foi investigar a reorganização de outras áreas relacionadas ao comportamento motor, como o estriado, a substância negra e a medula espinhal. 17 ratos foram divididos aleatoriamente em três grupos: treinado (TR, n = 6), controle (CTL, n = 7) e sham (n = 4). Todos os animais receberam um implante de matriz de micro-eletrodos no córtex sensório-motor. Os animais dos grupos TR e CTL foram submetidos à LM contusa e os do grupo sham somente ao procedimento cirúrgico sem a LM. Foi realizada a avaliação eletrofisiológica antes da LM e nos 1º, 3º, 5º, 7º, 14º, 21º, 28º, 35º, 42º, 49º e 56º dias pós-operatórios (dPO) da lesão. O grupo TR realizou treinamento motor em uma esteira com velocidade controlada, tendo início no 5º dPO e foi realizado por 15 minutos, cinco vezes na semana. Os outros dois grupos ficaram sem treinamento. No 57º dPO, os animais foram sacrificados, e as medulas espinhais e os encéfalos foram coletados para análise imunohistoquímica. Os resultados eletrofisiológicos mostraram que houve uma diminuição significativa do número de neurônios corticais registrados ao longo do tempo para os animais com LM; existem neurônios que disparam em função do movimento mesmo após a LM, sendo o número desses neurônios significativamente menor nos animais controles; observou-se um padrão de atividade de potencial de campo local do córtex sensório-motor que antecede a ativação muscular. A análise imunohistoquímica do encéfalo mostrou diminuição significativa da imunoreatividade para o marcador de neurofilamentos no córtex motor do grupo CTL e no estriado para os grupos CTL e TR; no córtex somatossensorial houve aumento significativo desta marcação para o grupo TR; não houve diferença da imunoreatividade entre os grupos para o marcador de neurofilamentos na substância negra e nem para a proteína de vesícula, sinaptofisina, nas diferentes áreas encefálicas. Na medula espinhal verificou-se, na região rostral à lesão, aumento significativo da imunoreatividade para os marcadores de proteína associada ao microtúbulo 2 (MAP2), da sinapsina (SYS) e da proteína glial fibrilar ácida (GFAP) para o grupo TR e diminuição significativa da SYS para o grupo CTL; no segmento central à lesão, houve diminuição significativa da imunoreatividade para os marcadores MAP2 e SYS e aumento significativo para GFAP e OX-42 para os grupos CTL e TR; no segmento caudal à lesão houve diminuição significativa da imunoreatividade para os marcadores GFAP, SYS, MAP2 e OX-42 para o grupo CTL e aumento significativo do marcador MAP2 para o grupo TR. Os resultados obtidos neste trabalho mostram que a atividade física realizada na esteira após a LM é capaz de promover reorganização cortical sensório-motora e medular por meio da neuroproteção e neuroregeneração / Spinal cord injury (SCI) results in a devastating condition, which leads to motor and sensory deficits that impair the injured person functional performance. The understanding about the mechanisms involved in cortical reorganization after an efficient therapeutic strategy can provide relevant information for the improvement of assistive technology, such as neuroprosthesis. This work aimed to investigate the functional and structural changes in the sensorimotor cortex of spinal cord injured Wistar rats, which were submitted to treadmill training. A secondary objective was to investigate the reorganization of other areas related to the movement, such as striatum, substantia nigra and spinal cord. 17 rats were randomly divided into three groups: trained (TR, n = 6), control (CTL, n = 7) and sham (n = 4). All animals received a microelectrodes array in the sensorimotor cortex. Control and trained animals were submitted to contusive SCI and the sham group only to the surgical procedure without the contusion. Electrophysiological assessments were accomplished before SCI and on the 1st, 3rd, 5th, 7th, 14th, 21st, 28th, 35th, 42nd, 49th and 56th post-operative days (POd). The TR group performed the motor training on a treadmill with controlled speed, starting on the 5th POd and it was done for 15 minutes, five times per week. The other two groups did not receive any training. On the 57th POd, the animals were sacrificed and the spinal cords and brains were collected for immunohistochemistry analysis. Electrophysiological data revealed that there was a significant decrease of the cortical neurons number with time for the injured animals; there was neurons that fire in function of the movement even after the SCI, but the number of these neurons was significant smaller in CTL group; it was observed a pattern of sensorimotor local field potential activation before the muscular activation. Brain immunohistochemistry data showed immunoreactivity significant decrease for neurofilament staining of the CTL motor cortex and CTL and TR striatum; the somatosensory cortex had a significant increase of this maker for TR group; there was no difference between groups for the neurofilament maker in the substantia nigra and neither to the vesicle protein maker, synaptophysin, in the different brain areas. In the spinal cord rostral to the lesion there were significant increase of the immunoreactivity for the microtubule associated protein 2 (MAP2), synapsin (SYS) and glial fibrillary acidic protein (GFAP) for the TR group and significant decrease of SYS for the CTL group; central to the lesion, there were immunoreactivity significant decrease for the MAP2 and SYS makers and a significant increase for the GFAP and OX-42 makers in CTL and TR groups; and caudal to the lesion, there were immunoreactivity significant decrease for the GFAP, SYS, MAP2 and OX-42 for the CTL group and significant increase of MAP2 maker for the TR group. Together these findings show that the physical activity on a treadmill after spinal cord injury is capable of producing sensorimotor cortex and spinal cord reorganization throughout the neuroprotection and neuroregeneration

A lesão medular (LM) promove uma condição devastadora que resulta em comprometimentos sensorial e motor, impedindo o desempenho funcional do indivíduo. O entendimento sobre os mecanismos envolvidos na reorganização cortical após uma eficiente estratégia terapêutica pode fornecer informações relevantes para o aprimoramento de tecnologias assistivas, como neuropróteses. Este trabalho teve como objetivos investigar as alterações funcionais e estruturais no córtex sensório-motor de ratos Wistar submetidos à atividade física na esteira após a lesão medular contusa. O objetivo secundário foi investigar a reorganização de outras áreas relacionadas ao comportamento motor, como o estriado, a substância negra e a medula espinhal. 17 ratos foram divididos aleatoriamente em três grupos: treinado (TR, n = 6), controle (CTL, n = 7) e sham (n = 4). Todos os animais receberam um implante de matriz de micro-eletrodos no córtex sensório-motor. Os animais dos grupos TR e CTL foram submetidos à LM contusa e os do grupo sham somente ao procedimento cirúrgico sem a LM. Foi realizada a avaliação eletrofisiológica antes da LM e nos 1º, 3º, 5º, 7º, 14º, 21º, 28º, 35º, 42º, 49º e 56º dias pós-operatórios (dPO) da lesão. O grupo TR realizou treinamento motor em uma esteira com velocidade controlada, tendo início no 5º dPO e foi realizado por 15 minutos, cinco vezes na semana. Os outros dois grupos ficaram sem treinamento. No 57º dPO, os animais foram sacrificados, e as medulas espinhais e os encéfalos foram coletados para análise imunohistoquímica. Os resultados eletrofisiológicos mostraram que houve uma diminuição significativa do número de neurônios corticais registrados ao longo do tempo para os animais com LM; existem neurônios que disparam em função do movimento mesmo após a LM, sendo o número desses neurônios significativamente menor nos animais controles; observou-se um padrão de atividade de potencial de campo local do córtex sensório-motor que antecede a ativação muscular. A análise imunohistoquímica do encéfalo mostrou diminuição significativa da imunoreatividade para o marcador de neurofilamentos no córtex motor do grupo CTL e no estriado para os grupos CTL e TR; no córtex somatossensorial houve aumento significativo desta marcação para o grupo TR; não houve diferença da imunoreatividade entre os grupos para o marcador de neurofilamentos na substância negra e nem para a proteína de vesícula, sinaptofisina, nas diferentes áreas encefálicas. Na medula espinhal verificou-se, na região rostral à lesão, aumento significativo da imunoreatividade para os marcadores de proteína associada ao microtúbulo 2 (MAP2), da sinapsina (SYS) e da proteína glial fibrilar ácida (GFAP) para o grupo TR e diminuição significativa da SYS para o grupo CTL; no segmento central à lesão, houve diminuição significativa da imunoreatividade para os marcadores MAP2 e SYS e aumento significativo para GFAP e OX-42 para os grupos CTL e TR; no segmento caudal à lesão houve diminuição significativa da imunoreatividade para os marcadores GFAP, SYS, MAP2 e OX-42 para o grupo CTL e aumento significativo do marcador MAP2 para o grupo TR. Os resultados obtidos neste trabalho mostram que a atividade física realizada na esteira após a LM é capaz de promover reorganização cortical sensório-motora e medular por meio da neuroproteção e neuroregeneração / Spinal cord injury (SCI) results in a devastating condition, which leads to motor and sensory deficits that impair the injured person functional performance. The understanding about the mechanisms involved in cortical reorganization after an efficient therapeutic strategy can provide relevant information for the improvement of assistive technology, such as neuroprosthesis. This work aimed to investigate the functional and structural changes in the sensorimotor cortex of spinal cord injured Wistar rats, which were submitted to treadmill training. A secondary objective was to investigate the reorganization of other areas related to the movement, such as striatum, substantia nigra and spinal cord. 17 rats were randomly divided into three groups: trained (TR, n = 6), control (CTL, n = 7) and sham (n = 4). All animals received a microelectrodes array in the sensorimotor cortex. Control and trained animals were submitted to contusive SCI and the sham group only to the surgical procedure without the contusion. Electrophysiological assessments were accomplished before SCI and on the 1st, 3rd, 5th, 7th, 14th, 21st, 28th, 35th, 42nd, 49th and 56th post-operative days (POd). The TR group performed the motor training on a treadmill with controlled speed, starting on the 5th POd and it was done for 15 minutes, five times per week. The other two groups did not receive any training. On the 57th POd, the animals were sacrificed and the spinal cords and brains were collected for immunohistochemistry analysis. Electrophysiological data revealed that there was a significant decrease of the cortical neurons number with time for the injured animals; there was neurons that fire in function of the movement even after the SCI, but the number of these neurons was significant smaller in CTL group; it was observed a pattern of sensorimotor local field potential activation before the muscular activation. Brain immunohistochemistry data showed immunoreactivity significant decrease for neurofilament staining of the CTL motor cortex and CTL and TR striatum; the somatosensory cortex had a significant increase of this maker for TR group; there was no difference between groups for the neurofilament maker in the substantia nigra and neither to the vesicle protein maker, synaptophysin, in the different brain areas. In the spinal cord rostral to the lesion there were significant increase of the immunoreactivity for the microtubule associated protein 2 (MAP2), synapsin (SYS) and glial fibrillary acidic protein (GFAP) for the TR group and significant decrease of SYS for the CTL group; central to the lesion, there were immunoreactivity significant decrease for the MAP2 and SYS makers and a significant increase for the GFAP and OX-42 makers in CTL and TR groups; and caudal to the lesion, there were immunoreactivity significant decrease for the GFAP, SYS, MAP2 and OX-42 for the CTL group and significant increase of MAP2 maker for the TR group. Together these findings show that the physical activity on a treadmill after spinal cord injury is capable of producing sensorimotor cortex and spinal cord reorganization throughout the neuroprotection and neuroregeneration

Les lésions spinales conduisent à des altérations majeures des fonctions sensorimotrices. Les récupérations fonctionnelles consécutives à ces atteintes sont très limitées, notamment en raison des capacités réduites de réparation des tissus endommagés dans le SNC. En outre, ces récupérations dépendent notamment de plusieurs processus cellulaires tels que l'activation astrogliale qui conduit à la formation de la cicatrice gliale, ou encore l'inflammation dont les cellules microgliales et les mastocytes sont les effecteurs les plus précoces. Cette inflammation est connue pour exacerber les dommages tissulaires et restreindre les possibilités de récupération. Cependant, des études récentes chez l'animal et chez l'Homme montrent que l'inflammation pourrait également avoir des effets favorisant les processus de récupération. Le but de cette thèse était de mieux comprendre les liens qui existent entre neuroinflammation, neuroplasticité et récupérations fonctionnelles après lésion spinale. L’objectif expérimental visait à examiner les réactivités microgliales, mastocytaires et astrocytaires post-lésionnelles, en parallèle avec des restaurations fonctionnelles. Dans ce contexte nous nous sommes plus particulièrement intéressés à l'influence d'une cytokine pro-inflammatoire, le Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) sur ces processus inflammatoires et la plasticité fonctionnelle après une hémisection C4-C5 chez le rat adulte. L’ensemble de nos travaux suggère que le GM-CSF pourrait agir par l’intermédiaire de plusieurs événements cellulaires et moléculaires, en favorisant des phénomènes de plasticité adaptatifs et la récupération partielle de fonctions altérées. / Spinal cord injuries are mostly of traumatic origin and result in major sensorimotor deficits. Postlesion functional recovery is limited, especially because of the reduced capacity of repairing damaged tissues. Moreover, this recovery depends specifically on several cellular processes such as astroglial activation conducting to glial scar formation, or inflammation for which microglial and mast cells are the earliest effectors. This inflammation is known to exacerbate tissue damages and restrain the capacity to recover. However, recent studies in animals and humans show that inflammation may also have beneficial aeffects on recovery processes. The studies conducted during my doctoral research were intended to better understand the links between neuroinflammation, neuroplasticity and functional recovery following spinal cord injury. We aimed at examining microglial, mast cells and astroglial reactivities after the injury, in relation with functional recovery of somatosensory and motor functions. In this context, we were particularly interested in the influence of Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) on inflammatory and plasticity mechanisms after a C4-C5 hemisection in the adult rat. Our doctoral research suggests that GM-CSF could act through several cellular and molecular events promoting adaptive plasticity phenomena underlying partial recovery of impaired functions.