FETAL SPINAL-CORD TRANSPLANTS SUPPORT THE DEVELOPMENT OF TARGET REACHING AND COORDINATED POSTURAL ADJUSTMENTS AFTER NEONATAL CERVICAL SPINAL-CORD INJURY
Ps. Diener et Bs. Bregman, FETAL SPINAL-CORD TRANSPLANTS SUPPORT THE DEVELOPMENT OF TARGET REACHING AND COORDINATED POSTURAL ADJUSTMENTS AFTER NEONATAL CERVICAL SPINAL-CORD INJURY, The Journal of neuroscience, 18(2), 1998, pp. 763-778
Neonatal midthoracic spinal cord injury disrupts the development of po
stural reflexes and hindlimb locomotion. The recovery of rhythmical al
ternating movements, such as locomotion, is enhanced in injured animal
s receiving fetal spinal cord transplants. Neonatal cervical spinal co
rd injury disrupts not only locomotion but also skilled forelimb movem
ent. The aims of this study were to determine the consequences of cerv
ical spinal cord injury on forelimb motor function and to determine wh
ether transplants of fetal spinal cord support normal development of s
killed forelimb use after this injury. Three-day-old rats received a c
ervical spinal cord lesion at C3, with or without a transplant of feta
l cervical spinal cord (embryonic day 14); unoperated pups served as c
ontrols. Animals were examined daily during the first month of life us
ing a behavioral protocol that assessed reflexes, postural reactions,
and forelimb motor skills. They also were trained and tested as adults
to assess performance in goal-directed reaching tasks. The onset of p
ostural reflexes was delayed in the lesion-only group, and goal-direct
ed reaching and associated postural adjustments failed to develop. The
transplant group developed reflex responses and skilled forelimb acti
vity that resembled normal movement patterns. Transplant animals devel
oped both target reaching and accompanying postural adjustments. Targe
t reaching requires integration of segmental, intersegmental, and supr
aspinal input to propriospinal and motor neurons over many spinal cord
levels. Transplants may support the reestablishment of input onto the
se neurons, permitting the development of skilled forelimb activity af
ter neonatal cervical spinal cord injury. The neuroanatomical reorgani
zation of descending and propriospinal input was examined in the compa
nion paper (Diener and Bregman, 1998).