 Amyotrophic lateral sclerosis ALS is due to neurodegeneration of upper and lower motor neurons, leading to muscle atrophy, paralysis and death. However, there is growing evidence that interneurons involved in the gain regulation of spinal motoneuron lower motor neurons and in sensorimotor integration may participate in the pathogenesis of ALS. While sensory afferents in the peripheral nerve are traditionally thought to be unaffected at the beginning of the disease, diffusion MRI has revealed degeneration and demyelination of the posterior columns in the spinal cord of patients recently diagnosed with ALS, and there are sporadic reports of sensory involvement. Early alteration of the sensorimotor integration could participate to the degeneration of motor neurons and interneurons. The goal of the project is to further investigate sensorimotor integration at spinal level in human patients recently diagnosed with ALS, and to study whether an interneuron pathology could participate in ALS pathogenesis. 