The average number of traced RtST collaterals that entered the grey matter (normalized to traced RtST axon count and the length of the section analyzed) was similar between dSTAG (3.0 x [10.sup.-6] [+ or -] 0.7 x [10.sup.-6] collaterals/traced axon/[micro]m) and cSTAG (1.4 x [10.sup.-6] [+ or -] 0.4 x [10.sup.-6] collaterals/traced axon/[micro]m) animals (p = 0.12; Figures 5(a) and 5(b)).
At this distance, dSTAG animals had 5.6 x [10.sup.-6] [+ or -] 2.0 x [10.sup.-6] collaterals/traced axon/[micro]m and cSTAG animals had 1.2 x [10.sup.-6] [+ or -] 0.6 x [10.sup.-6] collaterals/traced axon/[micro]m.
Interestingly, more synaptic connections with PrINs were found when the second SCI was delayed by 2 weeks (dSTAG) compared to animals that received both SCIs at the same time (cSTAG), which could explain the superior recovery of these animals.
However, dSTAG collaterals exhibited enhanced growth compared to cSTAG collaterals.
Since cSTAG animals can hardly generate movements, self-training and the resulting plasticity are hindered.
Our results showing some modest recovery of hindlimb motor function in cSTAG animals are consistent with other studies from our lab using the cSTAG model [12, 25] but in contrast with other studies [10, 54] where rodents that underwent cSTAG hemisections recovered very little.
 induced locomotor-like activity by stimulating the brainstem electrically soon after cSTAG SCI in an in vitro preparation.
It is noteworthy that in the cSTAG group the hindlimbs ipsilateral to the T10 SCI were nearly paralyzed as compared to the contralateral hindlimbs.
Caption: Figure 2: dSTAG animals displayed superior locomotor ability compared to cSTAG animals.
Schematics of spinal cord segments encompassing the lesions from representative dSTAG and cSTAG animals (c).
No significant differences in the number of soma in the grey matter were found between dSTAG and cSTAG groups (c).