RT Journal Article
SR Electronic
T1 Step Training Reinforces Specific Spinal Locomotor Circuitry in Adult Spinal Rats
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 7370
OP 7375
DO 10.1523/JNEUROSCI.1881-08.2008
VO 28
IS 29
A1 Ronaldo M. Ichiyama
A1 Grégoire Courtine
A1 Yury P. Gerasimenko
A1 Grace J. Yang
A1 Rubia van den Brand
A1 Igor A. Lavrov
A1 Hui Zhong
A1 Roland R. Roy
A1 V. Reggie Edgerton
YR 2008
UL http://www.jneurosci.org/content/28/29/7370.abstract
AB Locomotor training improves function after a spinal cord injury both in experimental and clinical settings. The activity-dependent mechanisms underlying such improvement, however, are sparsely understood. Adult rats received a complete spinal cord transection (T9), and epidural stimulation (ES) electrodes were secured to the dura matter at L2. EMG electrodes were implanted bilaterally in selected muscles. Using a servo-controlled body weight support system for bipedal stepping, five rats were trained 7 d/week for 6 weeks (30 min/d) under quipazine (0.3 mg/kg) and ES (L2; 40 Hz). Nontrained rats were handled as trained rats but did not receive quipazine or ES. At the end of the experiment, a subset of rats was used for c-fos immunohistochemistry. Three trained and three nontrained rats stepped for 1 h (ES; no quipazine) and were returned to their cages for 1 h before intracardiac perfusion. All rats could step with ES and quipazine administration. The trained rats had higher and longer steps, narrower base of support at stance, and lower variability in EMG parameters than nontrained rats, and these properties approached that of noninjured controls. After 1 h of stepping, the number of FOS+ neurons was significantly lower in trained than nontrained rats throughout the extent of the lumbosacral segments. These results suggest that training reinforces the efficacy of specific sensorimotor pathways, resulting in a more selective and stable network of neurons that controls locomotion.