[Synaptic mechanisms of descending influences on the facial nucleus motor neurons in the cat].

Intracellular recording of potentials revealed that stimulation of cerebral cortex, gyrus proreus and pyramidal tact evoked polysynaptic excitatory and postsynaptic potentials in the cat's facial motoneurons. Stimulation of lateral hypothalamus was characterized by exclusively excitatory polysynaptic effects. High degree of convergence of the above influences onto the facial motoneurons and possible mechanisms and pathways of cortical and hypothalamic control of facial motoneurons activity are discussed.

[Factors responsible for generation of multiple discharges in motor neurons of the nucleus of the facial nerve in cats].

Peculiarities of multiple discharges of facial nucleus motoneurons evoked to stimulation of caudal trigeminal nucleus were studied in acute experiments on cats by intracellular recording technique. The multiple discharge is shown to appear on the basis of gradual depolarization of the motoneuron membrane resulted from effective summation of high-frequency excitatory synaptic influences from the caudal trigeminal nucleus. Factors supporting the development of the gradual depolarization are dendritic location of synaptic terminals of trigeminal projecting neurons, dendritic origin of depolarizing after-potentials and high input resistance of the facial motoneuron membrane.

[Neuronal analysis of the projection of the caudal trigeminal nucleus to the nucleus of the facial nerve in cats].

Peculiarities of the trigeminal nucleus caudalis neurons which are projected to the facial nucleus were studied by microelectrode recording in cats. It is shown that the mentioned neurons are localized predominantly in ventral parts of the trigeminal nucleus caudalis and adjacent lateral reticular formation. Mono- and polysynaptic activation of efferent trigeminal neurons to pyramidal impulsation is described.

[Synaptic processes in motor neurons of the nucleus of the facial nerve upon stimulation of the caudal trigeminal nucleus].

Focal and postsynaptic potentials of facial motoneurons evoked by stimulation of the caudal trigeminal nucleus were studied in cats using extra- and intracellular recording technique. Pre- and post-synaptic components of focal potentials are shown. Four types of motoneuron responses are distinguished: EPSP generating single action potentials; gradual shift of depolarization evoking multiple discharges; rhythmical discharge of action potentials appearing at a low level of depolarization; EPSP and a sequence of EPSP-IPSP.

[Electrophysiologic characteristics of motor neurons of the cat facial nerve nucleus].

The antidromic activation of facial nucleus motoneurons to the stimulation of various branches of the facial nerve was studied by means of intracellular recording in cats. The time and amplitude characteristics of separate components of the antidromic spike were analyzed and fast and slow after-potentials were distinguished. A correlation was shown between the duration of the falling phase of the SD spike, the duration of its after-hyperpolarization and the impulse conductance time in the axon.