The effects of unilateral pyramidal tract section on hindlimb motor performance in the rat.

Most investigations on selective lesions of the pyramidal tract in rodents have focused on the functional impairment of the forelimbs. This study describes the effects of a unilateral transection of the pyramidal tract rostral to the decussation on hindlimb function. Using kinematic locomotion analysis, the narrow beam test, open field locomotion ranking, analysis of footprints and air righting, we found severe impairments including hypermetria, trunk instability, lateral shifts in weight support, toe dragging, and hindlimb exo-rotation. Most impairments recovered rapidly within the first week after operation. Slight hypermetria persisted after 4 weeks. The rather mild long term deficits after unilateral pyramidotomy may stress the need for extremely sensitive behavioural tasks to enable the detection. We conclude that the possibility to correlate regenerative changes following selective pyramidal tract lesions with hindlimb function is thus limited.