Effects of Electric Stimulation of the Crossed Olivocochlear Bundle on Single Auditory-Nerve Fibers in the Cat

Wiederhold, Michael L.; Kiang, N. Y. S.

doi:10.1121/1.1912234

Cited by 354 publications

(186 citation statements)

References 3 publications

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“…As described in Results, when the time courses of these shifts were characterized by a single exponential function, the mean time constant was 516 ms (SD = 186 ms, N = 28). This time constant is much too short to be a Bslow^efferent effect lasting tens of seconds (Sridhar et al, 1995;Cooper and Guinan, 2003), but is longer than expected for Bfast^MOC reflexes, which rise and decay on the order of 100 ms (Wiederhold and Kiang, 1970;Sridhar et al, 1995;. A somewhat slower efferent effect for DPOAEs was demonstrated by Liberman et al (1996) in cats and by Kim et al (2001) The magnitudes of the shifts measured in the current study for SFOAEs are similar to those reported by Kim et al (2001) for DPOAEs.…”

Section: Time Constant Of Postactivator Shiftsmentioning

confidence: 98%

Simultaneous Measurement of Noise-Activated Middle-Ear Muscle Reflex and Stimulus Frequency Otoacoustic Emissions

Goodman

Keefe

2006

JARO

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Otoacoustic emissions serve as a noninvasive probe of the medial olivocochlear (MOC) reflex. Stimulus frequency otoacoustic emissions (SFOAEs) elicited by a low-level probe tone may be the optimal type of emission for studying MOC effects because at low levels, the probe itself does not elicit the MOC reflex J. Assoc. Res. Otolaryngol. 4:521]. Based on anatomical considerations, the MOC reflex activated by ipsilateral acoustic stimulation (mediated by the crossed olivocochlear bundle) is predicted to be stronger than the reflex to contralateral stimulation. Broadband noise is an effective activator of the MOC reflex; however, it is also an effective activator of the middle-ear muscle (MEM) reflex, which can make results difficult to interpret. The MEM reflex may be activated at lower levels than measured clinically, and most previous human studies have not explicitly included measurements to rule out MEM reflex contamination. The current study addressed these issues using a higherfrequency SFOAE probe tone to test for cochlear changes mediated by the MOC reflex, while simultaneously monitoring the MEM reflex using a lowfrequency probe tone. Broadband notched noise was presented ipsilaterally at various levels to elicit probetone shifts. Measurements are reported for 15 normal-hearing subjects. With the higher-frequency probe near 1.5 kHz, only 20% of subjects showed shifts consistent with an MOC reflex in the absence of an MEM-induced shift. With the higher-frequency probe near 3.5 kHz, up to 40% of subjects showed shifts in the absence of an MEM-induced shift. However, these responses had longer time courses than expected for MOC-induced shifts, and may have been dominated by other cochlear processes, rather than MOC reflex. These results suggest caution in the interpretation of effects observed using ipsilaterally presented acoustic activators intended to excite the MOC reflex.

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Section: Time Constant Of Postactivator Shiftsmentioning

confidence: 98%

Simultaneous Measurement of Noise-Activated Middle-Ear Muscle Reflex and Stimulus Frequency Otoacoustic Emissions

Goodman

Keefe

2006

JARO

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“…When it was first reported (Goldberg and Fernández 1980), the fact that efferents exerted an excitatory action in the mammalian vestibular labyrinth seemed surprising since other studies had shown that efferent actions in auditory and vibratory organs were inhibitory (Wiederhold and Kiang 1970;Russell 1973, 1976;Furukawa 1981;Ashmore and Russell 1982;Art et al 1984). In retrospect, the challenge was to explain how an efferent action based on ionotropic, cholinergic neurotransmission (Bobbin andKonishi 1971, 1974) could give rise to inhibition.…”

Section: Excitatory Nature Of the Responsesmentioning

confidence: 99%

“…In the case auditory or vibratory receptors, the predominant efferent action so produced is an inhibition of afferent activity (Wiederhold and Kiang 1970;Flock and Russell 1973;1976;Furukawa 1981;Ashmore and Russell 1982;Art et al 1984). More heterogeneous responses have been seen in vestibular organs of frogs (Rossi et al 1980(Rossi et al , 1994Bernard et al 1985;Sugai et al 1991) and turtles (Brichta and Goldberg 2000) and include both increases and decreases in afferent discharge.…”

Section: Introductionmentioning

confidence: 99%

Efferent Actions in the Chinchilla Vestibular Labyrinth

Marlinski

Plotnik

Goldberg

2004

JARO

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Efferent fibers were electrically stimulated in the brain stem, while afferent activity was recorded from the superior vestibular nerve in barbiturate-anesthetized chinchillas. We concentrated on canal afferents, but otolith afferents were also studied. Among canal fibers, calyx afferents were recognized by their irregular discharge and low rotational gains. In separate experiments, stimulating electrodes were placed in the efferent cell groups ipsilateral or contralateral to the recording electrode or in the midline. While single shocks were ineffective, repetitive shock trains invariably led to increases in afferent discharge rate. Such excitatory responses consisted of fast and slow components. Fast components were large only at high shock frequencies (200-333/s), built up with exponential time constants <0.1 s, and showed response declines or adaptation during shock trains >1 s in duration. Slow responses were obtained even at shock rates of 50/s, built up and decayed with time constants of 15-30 s, and could show little adaptation. The more regular the discharge, the larger was the efferent response of an afferent fiber. Response magnitude was proportional to cv* b , a normalized coefficient of interspike-interval variation (cv*) raised to the power b = 0.7. The value of the exponent b did not depend on unit type (calyx vs. bouton plus dimorphic, canal vs. otolith) or on stimulation site (ipsilateral, contralateral, or midline). Responses were slightly smaller with contralateral or midline stimulation than with ipsilateral stimulation, and they were smaller for otolith, as compared to canal, fibers.An anatomical study had suggested that responses to contralateral afferent stimulation should be small or nonexistent in irregular canal fibers. The suggestion was not confirmed in this study. Contralateral responses, including the large responses typically seen in irregular fibers, were abolished by shallow midline incisions that should have severed crossing efferent axons.

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“…We have previously outlined a functional scenario for the presumed multipolar cells that receive olivocochlear input (Benson and Brown 1990). Action of olivocochlear fibers on the periphery decreases the responses of auditory nerve fibers (Wiederhold and Kiang 1970;Guinan and Gifford 1988). Olivocochlear branches may compensate for the reduced nerve fiber input by exciting certain multipolar cells of the cochlear nucleus.…”

Section: Convergence Of Type II Type I and Olivocochlear Inputs Ontmentioning

confidence: 99%

Postsynaptic Targets of Type II Auditory Nerve Fibers in the Cochlear Nucleus.

Benson

Brown

2004

JARO

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Type II auditory nerve fibers, which provide the primary afferent innervation of outer hair cells of the cochlea, project thin fibers centrally and form synapses in the cochlear nucleus. We investigated the postsynaptic targets of these synapses, which are unknown. Using serial-section electron microscopy of fibers labeled with horseradish peroxidase, we examined the border of the granule-cell lamina in mice, an area of type II termination that receives branches having swellings with complex shapes. About 70% of the swellings examined with the electron microscope formed morphological synapses, which is a much higher value than found in previous studies of type II swellings in other parts of the cochlear nucleus. The high percentage of synapses enabled a number of postsynaptic targets to be identified. Most of the targets were small dendrites. Two of these dendrites were traced to their somata of origin, which were cochlear-nucleus ''small cells'' situated at the border of the granule-cell lamina. These cells did not appear to receive any terminals containing synaptic vesicles that were large and round, indicating a lack of input from type I auditory nerve fibers. Nor did type II swellings or targets participate in the synaptic glomeruli formed by mossy terminals and the dendrites of granule cells. Other type II synapses were axosomatic and their targets were large cells, which were presumed multipolar cells and one cell with characteristics of a globular bushy cell. These large cells almost certainly receive additional input from type I auditory nerve fibers, which provide the afferent innervation of the cochlear inner hair cells. A few type II postsynaptic targets-the two small cells as well as a large dendrite-received synapses that had accompanying postsynaptic bodies, a likely marker for synapses of medial olivocochlear branches. These targets thus probably receive convergent input from type II fibers and medial olivocochlear branches. The diverse nature of the type II targets and the examples of segregated convergence of other inputs illustrates the synaptic complexity of type II input to the cochlear nucleus.

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Effects of Electric Stimulation of the Crossed Olivocochlear Bundle on Single Auditory-Nerve Fibers in the Cat

Cited by 354 publications

References 3 publications

Simultaneous Measurement of Noise-Activated Middle-Ear Muscle Reflex and Stimulus Frequency Otoacoustic Emissions

Simultaneous Measurement of Noise-Activated Middle-Ear Muscle Reflex and Stimulus Frequency Otoacoustic Emissions

Efferent Actions in the Chinchilla Vestibular Labyrinth

Postsynaptic Targets of Type II Auditory Nerve Fibers in the Cochlear Nucleus.

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