Résumé :
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Communication 690. The aim of this study was to determine whether central (vestibular) and peripheral (proprioceptive and cutaneous) afferent informations perturbations could affect the spinal nervous message integration of the motoneuron pool which innervate the soleus, an ankle extensor muscle which participate in the maintenance and regulation of postural activity. The inner ear lesion is obtained by surgical labyrinthectomy, and the peripheral afferent alteration is obtained after L3, L4, and L5 dorsal root transection. Five experimental groups are used: control (CONT), 3 days after bilateral labyrinthectomy (BL3D), 17 days after bilateral labyrinthectomy (BL17D), 3 days after deafferentation (DEAF3D), and 7 days after deafferentation (DEAF7D). The soleus motoneurons morphological approach (motoneuron soma size) as well as the monosynaptic reflex activity in the ventral L5 lumbar root are studied. These two approaches allowed to obtain information in the motoneuron excitability changes. Our morphological results indicate that the soleus motoneuron pool of the DEAF3D, DEAF7D, BL3D, and BL17D groups are shifted towards smaller size classes. The electrophysiological results are in progress. These results suggest that a peripheral or a supraspinal influence alterations could have effects on the intrinsic lumbar motoneuron properties.
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