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Afferent feedback during human walking| old_uid | 334 |
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| title | Afferent feedback during human walking |
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| start_date | 2005/12/08 |
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| schedule | 10h30 |
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| online | no |
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| summary | It is well established that sensory feedback plays a significant role in the regulation of human walking. Sensory activity may contribute to the motor control of walking in two fundamentally different ways. It may provide an error signal that generates a corrective response to a sudden external perturbation, and it may contribute to the pre-programmed motoneuronal drive - either enhancing the ongoing motor drive or modifying the motor program.
Here, we review some of our recent data that illustrate these two roles.
When a rapid dorsiflexion perturbation is applied to the ankle during the stance phase of the step cycle, a reflex response with short- (SLR), medium-(MLR), and long-latency (LLR) components is observed in the soleus EMG. The
SLR and MLR bursts have onset latencies of approximately 40 ms and 75 ms, respectively, and receive strong contributions from the spinal group Ia and spinal group II afferent pathways, respectively. When a rapid plantar flexion perturbation is applied to the ankle, thereby unloading the plantar flexor muscles, a marked decline in the soleus EMG is observed. Such a perturbation can depress the EMG by more than 50% compared with a control step, depending on the phase of the step cycle that it is delivered. This
substantial depression in EMG demonstrates that sensory activity contributes importantly to the enhancement of the extensor muscle activation during the stance phase of the step cycle. On average, the EMG begins to decline
approximately 60ms after the perturbation, between that of SLR and MLR responses, suggesting that the afferent feedback that contributes to the enhancement of the locomotor EMG may be mediated differently than the afferent feedback that contributes to the spinal reflex responses.
I will discuss which afferent pathways might contribute to the enhancement of the locomotor drive. Therapeutic FES in walking will also be discussed. |
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| oncancel | Attention : changement de lieu |
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| responsibles | Lemoine, Marin |
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