Increasing evidence supports the use of physical activity for modifying brain activity and overall neurological health (Hillman et al, 2008). Specifically, aerobic exercise appears to improve cognitive efficacy with regards to decisional oddball tasks shown through the P300, whose amplitude and latency is augmented (Magnié et al., 2000). Furthermore, the effects of an acute bout of aerobic exercise on cardiovascular function are well established and are sustained following exercise cessation. Based on these findings, we proposed that (1) an acute bout of exercise may modulate movement-related cortical excitability within motor areas and (2) that transient effects would be sustained as long as heart rate (HR) remained elevated. Subjects (n=23) were placed in a soundproof booth and instructed to perform a self-paced unimanual ballistic wrist extension every 3-6 seconds of the right wrist while holding a moveable handle. The motion involved a brisk contraction followed by relaxation and positional reset, collected continuously for approximately 8 minutes. Electroencephalography was used to measure movement-related cortical activity of the Bereitschaftspotential (BP) time-locked to onset of muscle activity associated with movement. The BP is a slow negative self-paced movement related cortical potential that precedes movement by approximately 1500ms. Current work commonly separates the BP into 3 main components early, late, and re-afferent Potentials. The early BP is representative of motor preparation of supplementary motor area (SMA) activity while the late component is representative of motor execution from primary motor cortex (M1). Early and late components are often distinguished by a a characteristic change in slope; where the early BP is a slow negative rise and the late components a steeper negative deflection beginning approximately 500ms prior to movement onset. Broken down further the late component consists of a portion of negative slope before giving rise to a peak approximately 100ms after movement onset known as the motor potential (MP). Following baseline measures, subjects performed 20 minutes of aerobic exercise at a moderate intensity (70% of age-predicted maximum heart rate) on a recumbent cycle ergometer. After the cessation of exercise, BP measures were recorded at two time points: immediately post-exercise (Post) and following a return to iv baseline HR (Post[Rest]) and two additional measures separated by 15 minutes each (Post[Rest2] and Post[Rest3]) which was, on average, 45 minutes after the cessation of exercise. Electromyography (EMG) was employed over the extensor carpi radialis muscle belly to describe muscle burst activity and onset characteristics. Results determined that Early but not Late BP was influenced by aerobic exercise. This early movement related cortical adaptation is indicative of enhanced processing within supplementary motor area. Moreover, this effect was sustained for up to an hour and 15 minutes following exercise cessation. This data is suggestive that aerobic exercise influences on motor related cortical excitability is not driven by an aerobic exercise effect and is more indicative of a delayed neurotransmitter effect.

Increasing evidence supports the use of physical activity for modifying brain activity and overall neurological health (Hillman et al, 2008). Specifically, aerobic exercise appears to improve cognitive efficacy with regards to decisional oddball tasks shown through the P300, whose amplitude and latency is augmented (Magnié et al., 2000). Furthermore, the effects of an acute bout of aerobic exercise on cardiovascular function are well established and are sustained following exercise cessation. Based on these findings, we proposed that (1) an acute bout of exercise may modulate movement-related cortical excitability within motor areas and (2) that transient effects would be sustained as long as heart rate (HR) remained elevated. Subjects (n=23) were placed in a soundproof booth and instructed to perform a self-paced unimanual ballistic wrist extension every 3-6 seconds of the right wrist while holding a moveable handle. The motion involved a brisk contraction followed by relaxation and positional reset, collected continuously for approximately 8 minutes. Electroencephalography was used to measure movement-related cortical activity of the Bereitschaftspotential (BP) time-locked to onset of muscle activity associated with movement. The BP is a slow negative self-paced movement related cortical potential that precedes movement by approximately 1500ms. Current work commonly separates the BP into 3 main components early, late, and re-afferent Potentials. The early BP is representative of motor preparation of supplementary motor area (SMA) activity while the late component is representative of motor execution from primary motor cortex (M1). Early and late components are often distinguished by a a characteristic change in slope; where the early BP is a slow negative rise and the late components a steeper negative deflection beginning approximately 500ms prior to movement onset. Broken down further the late component consists of a portion of negative slope before giving rise to a peak approximately 100ms after movement onset known as the motor potential (MP). Following baseline measures, subjects performed 20 minutes of aerobic exercise at a moderate intensity (70% of age-predicted maximum heart rate) on a recumbent cycle ergometer. After the cessation of exercise, BP measures were recorded at two time points: immediately post-exercise (Post) and following a return to iv baseline HR (Post[Rest]) and two additional measures separated by 15 minutes each (Post[Rest2] and Post[Rest3]) which was, on average, 45 minutes after the cessation of exercise. Electromyography (EMG) was employed over the extensor carpi radialis muscle belly to describe muscle burst activity and onset characteristics. Results determined that Early but not Late BP was influenced by aerobic exercise. This early movement related cortical adaptation is indicative of enhanced processing within supplementary motor area. Moreover, this effect was sustained for up to an hour and 15 minutes following exercise cessation. This data is suggestive that aerobic exercise influences on motor related cortical excitability is not driven by an aerobic exercise effect and is more indicative of a delayed neurotransmitter effect.

Le membre fantôme correspond à la persistance de perceptions sensitives et motrices attribuées au membre amputé. Des douleurs chroniques parfois invalidantes ainsi que des capacités d’évocation de mouvements dans le membre absent sont fréquemment rapportées. Très peu connue, cette motricité résiduelle est souvent considérée comme de l’imagerie motrice. Le premier objectif de cette thèse est de réinterroger le statut psychologique des mouvements de membre fantôme. Le second objectif est d’étudier le lien entre le contrôle moteur dans le membre fantôme et les réorganisations corticales dans le cortex moteur du sujet amputé. Au moyen de tests comportementaux et d’examens en Imagerie par Résonnance Magnétique fonctionnelle (IRMf), ces travaux de thèse ont permis de dissocier expérimentalement une forme de perceptions kinesthésiques associée à de l’imagerie motrice et une autre forme associée à de l’exécution motrice dans le membre fantôme. Cette distinction repose à la fois sur des différences de performances et sur le recrutement de régions cérébrales partiellement distinctes. Au-delà de cette distinction physiologique, les résultats obtenus suggèrent que les mouvements de membre fantôme s’apparentent à une forme d’exécution motrice plutôt qu’à de l’imagerie motrice. A travers le modèle du membre fantôme, ce travail aborde donc la question de la nature des informations menant à la perception d’un mouvement comme étant « exécuté ». Les altérations du fonctionnement cortical mises en évidence chez l’amputé peuvent représenter un modèle d’étude intéressant des différents mécanismes physiopathologiques relevés dans des situations de déficiences liées à une forme de plasticité « maladaptative ». Les observations cliniques et les examens en neuroimagerie menés au cours de cette thèse dressent en effet, un modèle relativement cohérent de l’organisation fonctionnelle du cortex après amputation. En particulier, l’existence d’un lien entre les réorganisations fonctionnelles au sein du cortex moteur et la qualité du contrôle moteur résiduel dans le membre fantôme permet de mieux comprendre les mécanismes sur lesquels reposent certaines thérapies antalgiques, comme les thérapies visuomotrices / The phantom limb is a sensory experience that is perceived to originate from the missing part. Amputees report that the phantom limb had certain sensory properties like touch and pain, as well as kinesthetic properties like being able to be moved voluntarily. Phantom limb movements are little-known and generally considered to reflect motor imagery rather than motor execution. The first aim of this thesis is to investigate whether amputees distinguish between executing a movement of the phantom limb and imagining moving the missing limb. The second aim is to examine the link between the quality of the motor control in the phantom limb and cortical reorganizations in the motor cortex of amputees. Behavioral tests and functional Magnetic Resonance Imaging (fMRI) results reveal the ability of amputees to make the distinction between execution and motor imagery in the phantom limb. This distinction is based both on differences in performances associated with the two tasks and the recruitment of partially distinct brain regions. Beyond this physiological distinction, this result suggests that phantom limb movements are similar to executed movements and differ from imagined movements. This raises important questions about the very nature of the processes underlying the awareness of a movement as being executed or imagined. The functional alterations in the motor cortex of amputees are somewhat similar to the pathophysiological mechanisms of maladaptative plasticity. Amputation could be a great model for its study. Indeed, the clinical and neuroimaging examinations conducted during this thesis led to a relatively coherent model of the functional reorganizations in the motor cortex after a limb-amputation and their relationships with behavioral variables. In particular, the relationship between functional reorganizations in the motor cortex and the quality of residual motor control in the phantom limb helps to understand the mechanisms underlying some analgesic therapies, such as the “visuomotor therapy”

Made available in DSpace on 2016-07-27T14:20:21Z (GMT). No. of bitstreams: 1 MARCOS PAULO GOMES DE ARAUJO.pdf: 1260442 bytes, checksum: 955ac57258629e7d5991a3817f55a8ac (MD5) Previous issue date: 2014-03-14 / Among several motor skills training techniques, covert rehearsal (or covert practice, mental training, symbolic repetition, mental practice, mental rehearsal, imagined execution, visualization, mentalizing ) has been used to improve sportive performance. From a radical behaviorism perspective, imagining is conceived as covert behavior. To imagine is see something in the absence of the thing being seen, with this seeing in the absence analogous in nature to the seeing when the thing saw is present. Who is imagining, are not doing two different things in these two different situations, but the same thing. In this sense, imagining is behavior. The effect of covert rehearsal upon motor skills executions depends of variables such as the mode and/or context in which the technique is used. The objective of the present study was to verify the effect of training procedures composed by instructional variables and covert rehearsal technique upon the motor execution of the volleyball overhand serve. Eight (8) teenagers, both sexes (six [6] men), with ages between 13 and 15 years, regular basic level apprentices in a volleyball initiation course, served as experimental participants. Randomly distributed into three groups, all participants were exposed to four experimental conditions: Baseline (BL), Regular Training (RT), Instructed Covert Rehearsal Training (ICR) and Covert Rehearsal Training with a Model (CRM). Groups differ in the order of exposition to the conditions from the second one, with the BL as the first condition for all groups. In each condition, participants executed ten (10) overhand serves, everyone filmed by the experimenter. Thirteen (13) volleyball experts (judges) evaluated the last three (3) BL serves and the first three (3) serves executed after exposition to RT, ICR and CRM conditions. Executions filmed were presented randomly and judges used a specific protocol to evaluate and quantify serve adequacy, considering serves in four main components (initial position, ball throwing, ball attack and finalization). Statistical analyses to verify order effects showed that the different order expositions to the experimental conditions did not affect executions, with no significant differences observed between the three groups. Friedman variance analysis, with the experimental conditions data taken together, showed that, for 31,25% comparisons, significant differences were observed between BL executions and that after covert rehearsal conditions (specially, in the ICR condition, but in the CRM condition too), but in a minor percent between these conditions. Results were interpreted in terms of: 1) the developmental level of self-perceptive, verbal and motor repertoires of the apprentices trained, 2) the nature of the control that can be exerted by the instructional components in the covert rehearsal conditions and 3) the interrelation between verbal (speaker and listening behaviors) and perceptual (imagining) variables as related with motor performance. / Dentre as várias técnicas de treinamento de habilidades motoras, o ensaio encoberto (ou prática encoberta, treino mental, repetição simbólica, prática mental, ensaio mental, execução imaginada, visualização, mentalização) tem sido usada com o objetivo de melhorar o desempenho esportivo. Na perspectiva do behaviorismo radical, o imaginar é entendido como comportamento encoberto. Imaginar é ver algo na ausência da coisa vista, sendo este ver na ausência análogo em natureza ao ver quando o que se vê está presente. Quem imagina, não está fazendo duas coisas diferentes nas duas situações, mas a mesma coisa. Nesse sentido, imaginar é um comportamento. O efeito do ensaio encoberto sobre a execução de habilidades motoras depende de variáveis tais como o modo e/ou o contexto em que a técnica é utilizada. O objetivo do presente estudo foi verificar o efeito de treinamento composto por variáveis instrucionais e técnica de ensaio encoberto sobre a execução motora do saque por cima do voleibol. Oito (8) adolescentes, de ambos os sexos (6 homens), com idade variando entre 13 e 15 anos, alunos regulares de iniciação ao voleibol, serviram como participantes do experimento. Distribuídos aleatoriamente em três grupos, todos os participantes foram expostos a quatro condições experimentais: Linha de Base (LB), Treinamento Padrão (TP), Treinamento com Ensaio Encoberto Instruído (TEI) e Treinamento com Ensaio Encoberto com Modelo (TEM). Os grupos diferiram quanto à ordem de exposição às condições a partir da segunda, sendo a LB a primeira para todos os grupos. Em cada condição, os participantes executaram dez (10) saques, todos eles tendo sido filmados pelo experimentador. Treze (13) avaliadores peritos em voleibol avaliaram, assistindo aos filmes, a execução dos três (3) últimos saques da condição LB e a execução dos três (3) primeiros após a exposição às condições TP, TEI e TEM. Nos filmes, as execuções foram apresentadas em ordem aleatória e a avaliação foi feita a partir de protocolo específico para dimensionar a adequação do saque, a partir dos seus quatro componentes principais (posição inicial, lançamento da bola, ataque à bola e finalização). Análise estatística dos dados para verificar efeito de ordem de exposição às condições mostrou que tal efeito não ocorreu, não sendo significativas as diferenças entre os três grupos. Tomados os dados em conjunto por condição experimental, análise de variância de Friedman mostrou que, em 31,25% das comparações, diferenças significativas ocorreram entre as execuções em LB e aquelas pós-ensaios encobertos (em especial no TEI, mas também no TEM), mas em número bem menor entre as condições. Os resultados foram interpretados quanto: 1) ao nível de desenvolvimento dos repertórios auto perceptivo, verbal e motor dos aprendizes expostos aos treinamentos, 2) a natureza do controle que pode ser exercido pelos componentes instrucionais nas condições com ensaio encoberto e 3) a inter-relação entre variáveis verbais (comportamentos de falante e ouvinte) e perceptuais (imaginação) na relação com o desempenho motor.