Amphetamine-Enhanced Motor Training after Cervical Contusion Injury

Abstract

Individually, motor training, pharmacological interventions, and housing animals in an enriched environment (EE) following spinal cord injury (SCI) result in limited functional improvement but, when combined, may enhance motor function. Here, we tested amphetamine (AMPH)-enhanced skilled motor training following a unilateral C3-C4 contusion injury on the qualitative components of reaching and on skilled forelimb function, as assessed using single-pellet and staircase reaching tasks. Kinematic analysis evaluated the quality of the reach, and unskilled locomotor function was also tested. Animals receiving AMPH and skilled forelimb training performed better than operated control animals on qualitative reaching, but not on skilled reaching. Those that received the combination treatment and were housed in EE cages showed significantly less improvement in qualitative reaching and grasping. Kinematic analysis revealed a decrease in digit abduction during skilled reaching among all groups, with no differences among groups. Kinematics provided no evidence that improved function was related to improved quality of reach. There was no evidence of neuroprotection in the cervical spinal cord. The absence of evidence for kinematic improvement or neuroprotection suggested that AMPH-enhanced motor training is due primarily to supraspinal effects, an enhancement of attention during skilled motor training, or plasticity in supraspinal circuitry involved with motor control.