title: Effect of stimulating the lumbar skin caudal to a complete spinal cord injury on hindlimb locomotion.
abstract: Sensory feedback is a potent modulator of the locomotor pattern generated by spinal networks. The purpose of this study was to assess the effect of cutaneous inputs from the back on the spinal-generated locomotor pattern. The spinal cord of six adult cats was transected at low thoracic levels. Cats were then trained to recover hindlimb locomotion. During experiments, the skin overlying lumbar vertebrae L2 to L7 was mechanically stimulated by a small calibrated clip or by manual pinching. Trials without and with cutaneous stimulation were performed at a treadmill speed of 0.4 m/s. Although manually pinching the skin completely stopped hindlimb locomotion and abolished weight support, cutaneous stimulation with the calibrated clip produced smaller effects. Specifically, more focalized cutaneous stimulation with the clip reduced flexor and extensor muscle activity and led to a more caudal positioning of the paw at contact and liftoff. Moreover, cutaneous stimulation with the clip led to a greater number of steps with improper nonplantigrade paw placements at contact and paw drag at the stance-to-swing transition. The most consistent effects on the hindlimb locomotor pattern were observed with cutaneous stimulation at midlumbar levels, from L3 to L5. The results indicate that cutaneous stimulation of the skin modulates the excitability of spinal circuits involved in generating locomotion and weight support, particularly at spinal segments thought to be critical for rhythm generation.
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Physiology and Biophysics, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Hurteau
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Physiology and Biophysics, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Yann
authors.initials: Y
authors.lastname: Thibaudier
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Physiology and Biophysics, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Charline
authors.initials: C
authors.lastname: Dambreville
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Physiology and Biophysics, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Corinne
authors.initials: C
authors.lastname: Desaulniers
authors.affiliation: Faculty of Medicine and Health Sciences, Department of Physiology and Biophysics, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada alain.frigon@usherbrooke.ca.
authors.forename: Alain
authors.initials: A
authors.lastname: Frigon
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002415:Cats; D063226:Central Pattern Generators / Q000503:physiopathology; D002908:Chronic Disease; D004195:Disease Models, Animal; D004567:Electrodes, Implanted; D004576:Electromyography; D056228:Feedback, Sensory / Q000502:physiology; D006614:Hindlimb / Q000503:physiopathology*; D008124:Locomotion / Q000502:physiology*; D008161:Lumbosacral Region; D018482:Muscle, Skeletal / Q000503:physiopathology; D010812:Physical Stimulation / Q000379:methods*; D020127:Recovery of Function / Q000502:physiology; D012867:Skin / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013904:Thoracic Vertebrae; D014110:Touch / Q000502:physiology*
keywords: spinal pattern generator