[Neuronal mechanisms of red nucleus interaction with brain stem structures].

Axon collaterals of rubrospinal neurons to various brainstem structures were identified in acute experiments in cats using the technique of intracellular recording of antidromic action potentials in combination with collision testing. A systemic principle of organization of the rubrospinal influences as well as a tendency to synchronous arrival of rubral impulses at various brainstem centres are shown. Most of the brainstem centres are relay nuclei sending direct efferent projections to those cerebellar areas which, in turn, control the red nucleus activity. Besides this loop which provides dynamic cerebellar control of motor activity, the somatosensory information transmission from the dorsal column nuclei of the spinal cord directly to the red nucleus is shown. The recorded mono- and polysynaptic EPSPs evoked by stimulation of the dorsal column nuclei are characterized by peculiarities which suggest that they originate in various parts of the somadendritic membrane of the red nucleus neurons. The mechanisms of integration of the descending motor command by the red nucleus are discussed.