That is generally what happened - this lab previously found gabapentin could help restore upper limb function after a spinal cord injury, and was following up by testing whether gabapentin combined with classic post-SCI treadmill training could improve recovery even further. They found no additional forelimb function, but noticed mice that didn't get gabapentin were averse to rehab, and began looking for reasons behind that. There's more to learn about gabapentin's effects on mental health in SCI at the cellular level, but social support/group setting in lieu of the drug induced rehab participation.