title: Output Properties of the Cortical Hindlimb Motor Area in Spinal Cord-Injured Rats.
abstract: The purpose of this study was to examine neuronal activity levels in the hindlimb area of motor cortex following spinal cord injury (SCI) in rats and compare the results with measurements in normal rats. Fifteen male Fischer-344 rats received a 200 Kdyn contusion injury in the thoracic cord at level T9-T10. After a minimum of 4 weeks following SCI, intracortical microstimulation (ICMS) and single-unit recording techniques were used in both the forelimb and hindlimb motor areas (FLA, HLA) under ketamine anesthesia. Although movements could be evoked using ICMS in the forelimb area with relatively low current levels, no movements or electromyographical responses could be evoked from ICMS in the HLA in any of the injured rats. During the same procedure, electrophysiological recordings were obtained with a single-shank, 16-channel Michigan probe (Neuronexus) to monitor activity. Neural spikes were discriminated using principle component analysis. Neural activity (action potentials) was collected and digitized for a duration of 5 min. Despite the inability to evoke movement from stimulation of cortex, robust single-unit activity could be recorded reliably from hindlimb motor cortex in SCI rats. Activity in the motor cortex of SCI rats was significantly higher compared with uninjured rats, and increased in hindlimb and forelimb motor cortex by similar amounts. These results demonstrate that in a rat model of thoracic SCI, an increase in single-unit cortical activity can be reliably recorded for several weeks post-injury.
authors.affiliation: 1 Molecular and Integrative Physiology, University of Kansas Medical Center , Kansas City, Kansas.|2 Landon Center On Aging, University of Kansas Medical Center , Kansas City, Kansas.
authors.forename: Shawn B
authors.initials: SB
authors.lastname: Frost
authors.affiliation: 2 Landon Center On Aging, University of Kansas Medical Center , Kansas City, Kansas.
authors.forename: Caleb L
authors.initials: CL
authors.lastname: Dunham
authors.affiliation: 2 Landon Center On Aging, University of Kansas Medical Center , Kansas City, Kansas.
authors.forename: Scott
authors.initials: S
authors.lastname: Barbay
authors.affiliation: 1 Molecular and Integrative Physiology, University of Kansas Medical Center , Kansas City, Kansas.
authors.forename: Dora
authors.initials: D
authors.lastname: Krizsan-Agbas
authors.affiliation: 3 Kansas Intellectual and Developmental Disabilities Research Center, University of Kansas Medical Center , Kansas City, Kansas.
authors.forename: Michelle K
authors.initials: MK
authors.lastname: Winter
authors.affiliation: 4 Rehabilitation Medicine, University of Kansas Medical Center , Kansas City, Kansas.
authors.forename: David J
authors.initials: DJ
authors.lastname: Guggenmos
authors.affiliation: 2 Landon Center On Aging, University of Kansas Medical Center , Kansas City, Kansas.|3 Kansas Intellectual and Developmental Disabilities Research Center, University of Kansas Medical Center , Kansas City, Kansas.|4 Rehabilitation Medicine, University of Kansas Medical Center , Kansas City, Kansas.
authors.forename: Randolph J
authors.initials: RJ
authors.lastname: Nudo
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D004569:Electroencephalography; D004576:Electromyography; D055724:Electrophysiological Phenomena / Q000502:physiology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005552:Forelimb / Q000503:physiopathology; D006614:Hindlimb / Q000503:physiopathology*; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D051381:Rats; D011916:Rats, Inbred F344; D013119:Spinal Cord Injuries; D013904:Thoracic Vertebrae
keywords: cortical activity; hindlimb; rat motor cortex; spinal cord injury