[Synaptic excitation of reticulospinal neurons during the startle reaction in cats anesthetized with chloralose].

Synaptic processes in the bulbar and pontine reticulospinal neurons (RS-neurons) were studied in chloralose-anesthetized cats during startle reaction to somatic stimulation ("spino-bulbo-spinal"--SBS-reflex). Excitatory PSPs were found to be a main type of synaptic responses in the RS-neurons; they were oligosynaptic (including monosynaptic) and polysynaptic. The comparison between synaptic responses of RS-neurons and SBS-reflexes showed that the polysynaptic EPSPs were most effective in generation of a SBS descending volley. It was also shown that about half of bulbar and pontine RS-neurons were simultaneously involved in suprasegmental relay of the SBS-reflexes. Conduction velocities in their axons ranged between 30 and 98 m/s (mean 64.5 +/- 16.5 m/s). Some functional features of the reticular centre of startle reaction are discussed.