title: Longitudinal Evaluation of Residual Cortical and Subcortical Motor Evoked Potentials in Spinal Cord Injured Rats.
abstract: We have applied transcranial electrical stimulation to rats with spinal cord injury and selectively tested the motor evoked potentials (MEPs) conveyed by descending motor pathways with cortical and subcortical origin. MEPs were elicited by electrical stimulation to the brain and recorded on the tibialis anterior muscles. Stimulation parameters were characterized and changes in MEP responses tested in uninjured rats, in rats with mild or moderate contusion, and in animals with complete transection of the spinal cord. All injuries were located at the T8 vertebral level. Two peaks, termed N1 and N2, were obtained when changing from single pulse stimulation to trains of 9 pulses at 9 Hz. Selective injuries to the brain or spinal cord funiculi evidenced the subcortical origin of N1 and the cortical origin of N2. Animals with mild contusion showed small behavioral deficits and abolished N1 but maintained small amplitude N2 MEPs. Substantial motor deficits developed in rats with moderate contusion, and these rats had completely eliminated N1 and N2 MEPs. Animals with complete cord transection had abolished N1 and N2 and showed severe impairment of locomotion. The results indicate the reliability of MEP testing to longitudinally evaluate over time the degree of impairment of cortical and subcortical spinal pathways after spinal cord injuries of different severity.
authors.affiliation: 1 Group of Neuroplasticity and Regeneration, Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona , and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Bellaterra, Spain .|2 Present address: Faculty of Life Sciences, A.V. Hill Building, University of Manchester , Manchester, United Kingdom .
authors.forename: Elena
authors.initials: E
authors.lastname: Redondo-Castro
authors.affiliation: 1 Group of Neuroplasticity and Regeneration, Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona , and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Bellaterra, Spain .
authors.forename: Xavier
authors.initials: X
authors.lastname: Navarro
authors.affiliation: 1 Group of Neuroplasticity and Regeneration, Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona , and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Bellaterra, Spain .|3 Department of Integrative Biology and Physiology, University of California , Los Angeles, Los Angeles, California.
authors.forename: Guillermo
authors.initials: G
authors.lastname: García-Alías
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D004195:Disease Models, Animal; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D009069:Movement Disorders / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009434:Neural Pathways / Q000293:injuries / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013119:Spinal Cord Injuries / Q000473:pathology / Q000503:physiopathology*; D013904:Thoracic Vertebrae / Q000293:injuries; D013997:Time Factors; D065908:Transcranial Direct Current Stimulation
keywords: brain stem; locomotion; motor evoked potential, recovery; spinal cord injury