Forelimb motor performance following dorsal column, dorsolateral funiculi, or ventrolateral funiculi lesions of the cervical spinal cord in the rat.

The neuroanatomical basis of forelimb motor control was examined following various surgical spinal cord lesions in the rat. Focal myelotomies were made at spinal level C4 to determine the effects that damage to long-tract pathways in the dorsal columns, dorsolateral funiculi, and ventrolateral funiculi have on a forelimb reaching and pellet retrieval task. Dorsal column lesions did not significantly reduce retrieval performance but did yield: (i) qualitative alterations in digit use during grasp execution, (ii) targeting errors during reaching attempts, and (iii) an apparent lack of ability to sense the presence of a pellet in the paw. Damage to the dorsolateral funiculi produced significantly diminished pellet retrieval performance at all postlesion intervals due to a prominent grasp deficit involving impaired digit flexion. Lesions of the ventrolateral funiculi did not produce a sustained, significant reduction in retrieval performance, although a qualitative deficit characterized by a mild forelimb reaching hypometria and premature grasp execution was exhibited. Based on comparisons with previous supraspinal and peripheral lesion studies in rats and supraspinal and spinal lesion studies in other mammalian species, the current results indicate that organization of descending and ascending spinal long-tract motor control of the forelimb in the rat is very similar to that described in other mammals, including primates. Additionally, these results demonstrate that the rat can serve as a biomedically relevant model of behavioral impairment and recovery following cervical spinal cord injury.