Adult rat forelimb dysfunction after dorsal cervical spinal cord injury.
Repairing upper extremity function would significantly enhance the quality of life for persons with cervical spinal cord injury (SCI). Repair strategy development requires investigations of the deficits and the spontaneous recovery that occurs when cervical spinal cord axonal pathways are damaged. The present study revealed that both anatomically and electrophysiologically complete myelotomies of the C4 spinal cord dorsal columns significantly increased the adult rat's averaged times to first attend to adhesive stickers placed on the palms of their forepaws at 1 week. Complete bilateral myelotomies of the dorsal funiculi and dorsal hemisection, but not bilateral dorsolateral funiculi injuries, also similarly increased these times at 1 week. These data extend a previous finding by showing that a forepaw tactile sensory deficit that occurred in the adult rat after bilateral C4 spinal cord dorsal funiculi injury is due to damage of the dorsal columns. Averaged times to first attend to the stickers also decreased to those of sham-operated rats at 3 and 4 weeks post-dorsal hemisection with weekly testing. In contrast, a separate group of rats with dorsal hemisections had significantly increased times when tested only at 4 weeks. These data indicate that frequent assessment of this particular behavior in rats with dorsal hemisections extinguishes it and/or engenders a learned response in the absence of sensory axons in the dorsal columns and dorsolateral funiculi. This finding contrasted with weekly testing of grid walking where increased forelimb footfall numbers persisted for 4 weeks post-dorsal hemisection.
Onifer
Stephen M
SM
Kentucky Spinal Cord Injury Research Center, University of Louisville School of Medicine, Louisville, KY 40292, USA. smonifer@louisville.edu
Zhang
Yi Ping
YP
Burke
Darlene A
DA
Brooks
Donna L
DL
Decker
Julie A
JA
McClure
Natasha J
NJ
Floyd
Andrea R
AR
Hall
Jacob
J
Proffitt
Bryan L
BL
Shields
Christopher B
CB
Magnuson
David S K
DS
D000344:Afferent Pathways / Q000473:pathology / Q000503:physiopathology*; D000818:Animals; D001288:Attention / Q000502:physiology; D002574:Cervical Vertebrae; D004195:Disease Models, Animal; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005108:Extinction, Psychological / Q000502:physiology; D005552:Forelimb / Q000294:innervation / Q000503:physiopathology*; D007859:Learning Disabilities / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D008297:Male; D009431:Neural Conduction / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000502:physiology; D020886:Somatosensory Disorders / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D013116:Spinal Cord / Q000473:pathology / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000473:pathology / Q000503:physiopathology*; D014110:Touch / Q000502:physiology