Synaptic mechanisms of central control of motoneuronal activity in the facial nerve nucleus

The responses of motoneurons of the facial nerve nucleus (FNN), evoked by stimulations of the oculomotor nerve nucleus, Edinger-Westphal's nucleus,substantia nigra, and entopeduncular nucleus, were studied in acute experiments on anesthetized and immobilized cats. The FNN motoneurons were identified by their antidromic activation after stimulation of various branches of the facial nerve. Stimulation of the oculomotor nerve nucleus, Edinger-Westphal's nucleus, and ipsi- or contralateral parts of thesubstantia nigra evoked mono- and polysynaptic EPSP in the FNN motoneurons, while stimulation of the entopeduncular nucleus elicited only polysynaptic EPSP. The influences from the above structures were shown to converge on the same FNN motoneurons. The findings are discussed considering morphological peculiarities of the afferent inputs to the FNN.Neirofiziologiya/Neurophysiology, Vol. 27, No. 2, pp. 116–125, March–April, 1995.