Modifications of the vestibular nerve activity by stimulation of the efferent vestibular system

Riassunto La stimolazione elettrica della zona nucleare vestibolare in vicinanza del nucleo di Deiters (dove presumibilmente originano le fibre efferenti vestibolari) è seguita, dopo un periodo di latenza pressochè costante (22–32 msec), dalla comparsa di potenziali bioelettrici nel nervo vestibolare controlaterale.     

Modifications of the vestibular DC resting potentials by stimulation of the efferent vestibular system

Riassunto La stimolazione (termica, elettrica) del sistema vestibolare efferente induce delle variazioni nei potenziali continui labirintici, derivati a livello del crus commune. Viene data la dimostrazione dell'esistenza di un feedback loop tra i due labirinti.      

Magnets in guitarfish vestibular receptors

Summary Black magnetic particles are intermixed with white crystalline otoconia in the inner ear gravity receptors of a saltwater ray. Their size and composition suggest that they are multidomains of magnetite-ilmenite.Acknowledgments. We thank Dennis Fulgoni for technical assistance and the Instituto de Investigaciones Pesqueras, Cadiz, Spain, for assistance in obtaining guitarfish. This work was support in part by grant NS 12494, from the National Institute of Communicative Disorders and Stroke.     

Trigeminal stimulation modulates vestibular unitary activity

Summary 139 vestibular neurons were analyzed in 38 guinea-pigs after the stimulation of trigeminal fibers: increase or decrease of discharge rate and also rhythmic modulation of vestibular unitary activity were observed.This work was supported by grants of MPI and CNR.     

Electrophysiologic and anatomic demonstration of inhibitory commisural vestibular neurons in the tench (Tinca tinca)]

Horseradish peroxydase was injected intracellularly in some of the medullary neurons which, in Fish, exhibit a passive hyperpolarizing potential after spinal cord stimulation (this indicates that such neurons both electrical and chemical inhibitions of the Mauthner cells). With positive staining, commissural vestibular neurons were identified; their axons cross the midline and they establish connexions with the Mauthner cell and with vestibular neurons of both sides. Thus the existence of a crossed vestibular inhibitory pathway, previously suggested by electrophysiological studies in lower Vertebrates as well as in Mammals, is now correlated with histological evidence.     

A new stimulation technique of the crista ampullaris of the lateral canal in the adult cat: Study of the action potential of the vestibular nerve

Summary The stimulation of the crista ampullaris of the lateral canal by a short ampullopetal liquid flux produces on the pre-ganglionic vestibular fibres the appearance of a bimodal action potential. The amplitude of this action potential increases with the intensity of the stimulation. This stimulation also provokes the birth of an evoked potential at the level of the vestibular nuclei as well as an ocular jerk.Supported by the D.G.R.S.T. grant 77.7.0669 and I.N.S.E.R.M. (A.S.R. No. 6, grant 011).     

A new stimulation technique of the crista ampullaris of the lateral canal in the adult cat: study of the action potential of the vestibular nerve.

The stimulation of the crista ampullaris of the lateral canal by a short ampullopetal liquid flux produces on the pre-ganglionic vestibular fibres the appearance of a bimodal action potential. The amplitude of this action potential increases with the intensity of the stimulation. This stimulation also provokes the birth of an evoked potential at the level of the vestibular nuclei as well as an ocular jerk.     

On the adenosintriphosphatase activity of the particulates of the egg of the sea urchinParacentrotus lividus

Riassunto I particolati delle uova vergini di riccio di mare possono essere separati, a mezzo della centrifugazione differenziale, in due frazioni, una fortemente ed una scarsamente pigmentata. La prima mostra una attività ATPasica attivata da Mg con un massimo a pH 8.2; il massimo della seconda è invece a pH 6.4. Nelle preparazioni contenenti i due tipi di particolati si ritrovano i due massimi.