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Master's Dissertation
DOI
10.11606/D.47.2008.tde-03042009-104150
Document
Author
Full name
Maria Carolina dos Santos Fornari
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2008
Supervisor
Committee
Kohn, Andre Fabio (President)
Mezzarane, Rinaldo André
Okai, Liria Akie
Title in Portuguese
Padrão eletromiográfico de membros inferiores em resposta a perturbações posturais
Keywords in Portuguese
Centro de pressão
Eletromiografia
Neurofisiologia
Postura
Processos motores
Reflexo H
Reflexos medulares
Vias neurais
Abstract in Portuguese
A manutenção do equilíbrio depende da ativação sinérgica de músculos dos dois hemicorpos, e há evidências de que essa coordenação é mediada por circuitos medulares, que estão sob controle supra-segmentar. O objetivo desse trabalho é descrever mecanismos neurofisiológicos e biomecânicos envolvidos no controle postural de sujeitos saudáveis frente a uma perturbação provocada por uma contração reflexa, enfatizando-se os mecanismos associados à coordenação entre membros. A perturbação postural ocorreu em resposta a um estímulo elétrico unilateral no nervo tibial. Devido a restrições em estudos anteriores, utilizou-se uma ampla abordagem (múltiplos músculos, reflexos cruzados) e estimulação precisamente controlada. Os resultados mostraram um complexo padrão de ativação dos músculos dos membros inferiores bilateralmente. Logo após o estímulo, foram encontradas respostas de curta e média latência em músculos da perna e da coxa. Posteriormente, foram observadas algumas ações musculares de longa latência nos músculos mais distais, que provavelmente foram ativadas em resposta às oscilações posturais. As respostas musculares iniciais sugerem que as informações aferentes e os reflexos medulares possuem uma função muito importante na regulação da coordenação entre membros, durante a manutenção da postura ereta quieta.
Title in English
Electromyographic pattern in lower limbs in response to postural perturbations
Keywords in English
Center of pressure
Electromyography
H-reflex
Motor processes
Neural pathways
Neurophysiology
Posture
Spinal reflexes
Abstract in English
Balance depends on the synergic activation of muscles bilaterally, and there is evidence that this coordination is mediated by spinal circuits, which are under supra-spinal control. The objective of this study is to describe neurophysiologic and biomechanical mechanisms involved in the postural control of healthy subjects submitted to a disturbance provoked by a muscular reflex contraction. The postural perturbation was caused by a unilateral electric stimulation to the popliteal fossa. The analysis emphasizes the mechanisms associated with interlimb coordination. In this work, methodological approaches expanded those of previous work, the recordings being done bilaterally and the stimulus being precisely controlled. The results showed a complex pattern of bilateral muscular activation. Short and medium latency responses were found in the leg and thigh muscles. These were followed by some muscular activity at longer latencies, probably occurring due to the postural oscillations. The initial muscular responses suggest that the afferent inflow and the spinal cord reflexes have an important function in the between-limb coordination during the standing posture.
 
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FornariMCS.pdf (839.40 Kbytes)
Publishing Date
2009-04-29
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • FORNARI, Maria Carolina dos Santos, and KOHN, A. F. High frequency tendon reflexes in the human soleus muscle [doi:10.1016/j.neulet.2008.05.075]. Neuroscience Letters [online], 2008, vol. 440, p. 193-196.
  • FORNARI, Maria Carolina dos Santos, and KOHN, A. F. Postural oscillations in response to a muscle twitch caused by a stimulus. In Progress in Motor Control VI, Santos, 2007. Motor Control (Supplement Edition).Champaign (USA) : Human Kinetics, 2007. Abstract.
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