Biomaterial Database

Effects of electrical stimulation of efferent olivocochlear neurons on cat auditory-nerve fibers. I. Rate-level functions. 1988

J J Guinan, and M L Gifford

Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge.

In previous studies describing the effects of electrically stimulating the olivocochlear bundle, it seems possible that both medial and lateral (MOC and LOC) efferents may have been stimulated. To selectively stimulate MOC efferents, we used an electrode placed at the origin of the MOC efferents in the brainstem (MOC stimulation). For comparison, a stimulating electrode was placed in the fourth ventricle at the decussation of the crossed olivocochlear bundle where both MOC and LOC efferents are present (midline-OCB stimulation). Rate versus sound level functions from auditory-nerve fibers were obtained with and without efferent stimulation. Stimulation at either location shifted rate vs. level functions to higher sound levels and depressed the rate in the plateau. For fibers with high spontaneous rates, the level shifts and plateau depressions had slightly different distributions as a function of characteristic frequency. The average amplitudes of these effects were largest for midline-OCB stimulation, next largest for crossed MOC stimulation and smallest for uncrossed MOC stimulation. The qualitative pattern of the effects, however, did not depend on the location of the stimulus electrode. The amplitudes of the efferent-induced effects were different for auditory-nerve fibers with different spontaneous rates (by as much as a factor of three for the plateau depression). The results support several hypotheses: (1) the effects of midline-OCB stimulation are due only to the action of MOC efferents, (2) individual crossed and uncrossed MOC fibers produce similar effects, and (3) efferents differentially change the information carrying properties of auditory-nerve fibers in different spontaneous-rate categories. These results, taken together with anatomical data in the literature, are consistent with the hypothesis that, in the cat, MOC and midline-OCB stimulation have their effect solely through synapses on outer hair cells. The data are consistent with the hypothesis that the level shifts are produced by MOC efferents acting on outer hair cells to reduce the mechanical stimulus to inner hair cells. It seems likely that some other mechanism is required to produce the plateau depressions, at least for auditory-nerve fibers with high spontaneous rates.

UI	MeSH Term	Description	Entries
D009476	Neurons, Efferent	Neurons which send impulses peripherally to activate muscles or secretory cells.	Efferent Neurons,Efferent Neuron,Neuron, Efferent
D009847	Olivary Nucleus	A brainstem nuclear complex. in the hindbrain, also referred to as the olivary body. The olivary nuclear complex is a part of the MEDULLA OBLONGATA and the PONTINE TEGMENTUM. It is involved with motor control and is a major source of sensory input to the CEREBELLUM.	Basal Nucleus, Olivary,Nucleus Basalis, Olivary,Olivary Body,Olivary Complex,Olivary Nuclei,Complex, Olivary,Nucleus, Olivary,Nucleus, Olivary Basal,Olivary Basal Nucleus,Olivary Bodies
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003051	Cochlea	The part of the inner ear (LABYRINTH) that is concerned with hearing. It forms the anterior part of the labyrinth, as a snail-like structure that is situated almost horizontally anterior to the VESTIBULAR LABYRINTH.	Cochleas
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D006198	Hair Cells, Auditory	Sensory cells in the organ of Corti, characterized by their apical stereocilia (hair-like projections). The inner and outer hair cells, as defined by their proximity to the core of spongy bone (the modiolus), change morphologically along the COCHLEA. Towards the cochlear apex, the length of hair cell bodies and their apical STEREOCILIA increase, allowing differential responses to various frequencies of sound.	Auditory Hair Cells,Cochlear Hair Cells,Auditory Hair Cell,Cell, Cochlear Hair,Cells, Cochlear Hair,Cochlear Hair Cell,Hair Cell, Auditory,Hair Cell, Cochlear,Hair Cells, Cochlear
D000159	Vestibulocochlear Nerve	The 8th cranial nerve. The vestibulocochlear nerve has a cochlear part (COCHLEAR NERVE) which is concerned with hearing and a vestibular part (VESTIBULAR NERVE) which mediates the sense of balance and head position. The fibers of the cochlear nerve originate from neurons of the SPIRAL GANGLION and project to the cochlear nuclei (COCHLEAR NUCLEUS). The fibers of the vestibular nerve arise from neurons of Scarpa's ganglion and project to the VESTIBULAR NUCLEI.	Cranial Nerve VIII,Eighth Cranial Nerve,Cochleovestibular Nerve,Statoacoustic Nerve,Cochleovestibular Nerves,Cranial Nerve VIIIs,Cranial Nerve, Eighth,Cranial Nerves, Eighth,Eighth Cranial Nerves,Nerve VIIIs, Cranial,Nerve, Cochleovestibular,Nerve, Eighth Cranial,Nerve, Statoacoustic,Nerve, Vestibulocochlear,Nerves, Cochleovestibular,Nerves, Eighth Cranial,Nerves, Statoacoustic,Nerves, Vestibulocochlear,Statoacoustic Nerves,VIIIs, Cranial Nerve,Vestibulocochlear Nerves
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia