[Depolarization of primary afferents induced by selective activation of propriospinal tracts]

Primary afferent depolarization (PAD) in the lumbosacral enlargement of the spinal cord evoked by selective activation of propriospinal (PS) pathways was studied in anesthetized cats. Activation of PS pathways in the lateral funiculus was more effective for PAD generation than that in the ventral funiculi. Excitation of PS pathways evoked PAD in terminals of cutaneous and muscle fibres including Ia muscle fibres. Neuronal mechanisms of intersegmental distribution of PAD and its possible functions are discussed.