[Polarization of terminals of the primary afferents of the lumbar region of the spinal cord during fictitious locomotion]

Changes in electric polarization of lumbosacral primary afferent terminals were studied during fictious locomotion of immobilized decorticated and spinal cats. Fictitious locomotion was accompanied by a stable hyperpolarization of afferent terminals. In the presence of hyperpolarization a periodic depolarization took place with the rhythm of efferent activity. These tonic and phasic changes were observed in the terminals of all the studied groups of afferent fibres (cutaneous and muscle Ia and Ib). Periodic depolarization was in-phase indifferent ipsilateral lumbosacral segments. During fictitious gallop the changes in depolarization of primary afferent terminals were in-phase on different sides; during fictitious walking these periodic changes were of out-of-phase character. Physiological significance of changes in electric polarization of primary afferent terminals by the spinal locomotor generator is discussed on the basis of the data obtained.