Brain Advance Access originally published online on October 10, 2007
Brain 2007 130(11):2993-3003; doi:10.1093/brain/awm245
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Reaching training in rats with spinal cord injury promotes plasticity and task specific recovery
1McGill University, Centre for Neuronal survival, Montreal, 2University of Lethbridge, Centre for Behavioural Neuroscience, Lethbridge, 3University of Saskatchewan, Cameco MS Neuroscience Research Center, Sasakatoon and 4University of Alberta, Faculty of Rehabilitation Medicine, Edmonton, Canada
Correspondence to: Karim Fouad, University of Alberta, Faculty of Rehabilitation Medicine, 3-48 Corbett Hall, Edmonton T6G 2G4, Canada E-mail: karim.fouad{at}ualberta.ca
In the current study we examined the effects of training in adult rats with a cervical spinal cord injury (SCI). One group of rats received 6 weeks of training in a single pellet reaching task immediately after injury, while a second group did not receive training. Following this period changes in cortical levels of BDNF and GAP-43 were analysed in trained and untrained animals and in a group with training but no injury. In another group of rats, functional recovery was analysed in the reaching task and when walking on a horizontal ladder. Thereupon, the cortical forelimb area was electrophysiologically examined using micro-stimulation followed by tracing of the lesioned corticospinal tract (CST). We found that trained rats improved substantially in the reaching task, when compared to their untrained counterparts. Trained rats however, performed significantly worse with their injured forelimb when walking on a horizontal ladder. In parallel to the improved recovery in the trained task, we found that the cortical area where wrist movements could be evoked by micro-stimulation expanded in trained rats in comparison to both untrained and uninjured rats. Furthermore, collateral sprouting of lesioned CST fibres rostral to the injury was increased in trained rats. Post-injury training was also found to increase cortical levels of GAP-43 but not BDNF. In conclusion we show that training of a reaching task promotes recovery of the trained task following partial SCI by enhancing plasticity at various levels of the central nervous system (CNS), but may come at the cost of an untrained task.
Key Words: spinal cord injury; plasticity; rehabilitation; training, cortical reorganization
Abbreviations: SCI, spinal cord injury; CST, corticospinal tract; CNS, central nervous system; RST, rubrospinal tract; CPG, central pattern generator
Received May 30, 2007. Revised September 12, 2007. Accepted September 14, 2007.