| Abstract: | It was established in experiments on rhesus monkeys by intracellular recording and computer averaging that fast-conducting reticulo- and vestibulospinal fibers form monosynaptic excitatory links with lumbar alpha-motor neurons. The monosynaptic bulbospinal effects are retained after sectioning of the pyramids or after chronic destruction of the motor cortex. The mean amplitude of the reticulomotor neuronal EPSP is less than that of the corticomotor neuronal EPSP, however, the mean amplitudes of the EPSP of individual motor neurons can reach similar values. In contrast to the corticomotor neuronal projections, the bulbomotor neuronal projections are directed primarily toward the motor neurons of the proximal muscles. In addition to monosynaptic EPSP, reticulo- and vestibulospinal impulses evoke disynaptic EPSP and IPSP in the lumbar motor neurons of monkeys which are very similar to the disynaptic effects found in subprimates.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 3, No. 4, pp. 408–417, July–August, 1971. |
