Influence of the cortico-spinal system on cervical and lumbar motoneurons in the rat

In rats the connections of cortico-spinal fibres to cervical and lumbar motoneurons were examined using epicortical stimulation techniques. In cervical motoneurons, the synaptic response started in nearly 50% of the units with a monosynaptically transmitted EPSP, was of short duration and proved to be very effective. In contrast to that, the synaptic sequence found in lumbar motoneurons consisted in a small oligosynaptic and a prominent polysynaptic part. The differences in cortico-motoneuronal linkage correspond well with the different types of motor performance in fore- and hindlimbs.