title: Awake behaving electrophysiological correlates of forelimb hyperreflexia, weakness and disrupted muscular synchronization following cervical spinal cord injury in the rat.
abstract: Spinal cord injury usually occurs at the level of the cervical spine and results in profound impairment of forelimb function. In this study, we recorded awake behaving intramuscular electromyography (EMG) from the biceps and triceps muscles of the impaired forelimb during volitional and reflexive forelimb movements before and after unilateral cervical spinal cord injury (cSCI) in rats. C5/C6 hemicontusion reduced volitional forelimb strength by more than 50% despite weekly rehabilitation for one month post-injury. Triceps EMG during volitional strength assessment was reduced by more than 60% following injury, indicating reduced descending drive. Biceps EMG during reflexive withdrawal from a thermal stimulus was increased by 500% following injury, indicating flexor withdrawal hyperreflexia. The reduction in volitional forelimb strength was significantly correlated with volitional and reflexive biceps EMG activity. Our results support the hypothesis that biceps hyperreflexia and descending volitional drive both significantly contribute to forelimb strength deficits after cSCI and provide new insight into dynamic muscular dysfunction after cSCI. The use of multiple automated quantitative measures of forelimb dysfunction in the rodent cSCI model will likely aid the search for effective regenerative, pharmacological, and neuroprosthetic treatments for spinal cord injury.
authors.affiliation: The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080, United States. Electronic address: pdg140030@utdallas.edu.
authors.forename: Patrick Daniel
authors.initials: PD
authors.lastname: Ganzer
authors.affiliation: The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080, United States. Electronic address: ecm081000@utdallas.edu.
authors.forename: Eric Christopher
authors.initials: EC
authors.lastname: Meyers
authors.affiliation: The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080, United States. Electronic address: ams091000@utdallas.edu.
authors.forename: Andrew Michael
authors.initials: AM
authors.lastname: Sloan
authors.affiliation: The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080, United States. Electronic address: Reshma.Maliakkal@utdallas.edu.
authors.forename: Reshma
authors.initials: R
authors.lastname: Maliakkal
authors.affiliation: The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080, United States; The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080, United States. Electronic address: adr081000@utdallas.edu.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ruiz
authors.affiliation: The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080, United States; The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080, United States. Electronic address: kilgard@utdallas.edu.
authors.forename: Michael Paul
authors.initials: MP
authors.lastname: Kilgard
authors.affiliation: The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080, United States; The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080, United States. Electronic address: renn@utdallas.edu.
authors.forename: LeMoine Rennaker
authors.initials: LR
authors.lastname: Robert
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D005552:Forelimb / Q000294:innervation / Q000503:physiopathology*; D007537:Isometric Contraction; D018908:Muscle Weakness / Q000209:etiology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012021:Reflex, Abnormal / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000150:complications* / Q000473:pathology*; D013997:Time Factors; D014851:Wakefulness
keywords: Electromyography; Forelimb; Hyperreflexia; Spasticity; Spinal cord injury; Strength