[Features of activation of reticulospinal neurons of the pons and medulla oblongata of the cat by somatosensory stimuli of different modalities].

Response of reticulo-spinal (RS) neurons in two reticular structures (n. reticularis pontis caudalis and n. reticularis gigantocellularis) to electrical nerve stimulation and natural mechanical non-nociceptive (tapping) and nociceptive (pinch and prick) stimuli were studied in chloralose-anesthetized cats. Essential differences in sensory properties of the pontine and bulbar RS-neurons were found. About a half of bulbar RS-neurons (43%) were activated only by high-threshold somatic afferents and nociceptive stimuli, the rest--by both nociceptive and non-nociceptive ones. On the contrary the most of pontine neurons (81%) responded either to non-nociceptive or to both noci- and non-nociceptive stimuli. A clear-cut correlation between sensory characteristics of the RS-neurons and their axon conduction velocities was established. Data obtained evidence for the existence of some spatial (rostro-caudal) differentiation of brainstem RS-neurons with different functional properties. Peculiarities of this differentiation and its possible functional significance are discussed.