[Rubrofugal influences on the spike activity of neurons of the medial reticulo-spinal tract]

Abstract

Synaptic influences from the red nucleus on the activity of the medial reticulo-spinal tract fibres were studied by microelectrode recording in throacic spinal cord of an anesthetized cat. It is found that the red nucleus establishes monosynaptic connections with many pontine and medullary reticulo-spinal neurons with fast (60-105 m/s) and moderate conducting (45-60 m/s) axons. Background activity of these fibres (characterized by grouping of impulses) is accelerated by repetitive stimulation of the red nucleus. Most neurons with slow conducting axons (10-45 m/s) are polysynaptically excited by the red nucleus stimulation, but their background activity (with uniform distribution of impulses) is depressed. Such rubro-reticular influences were also observed in cats with preliminary destroyed tectal and interstitial structures. Some functional aspects of the rubro-reticulo-spinal system are discussed.