The origin of efferent fibers to the inner ear in a turtle (Terrapene ornata). A horseradish peroxidase study

Strutz, J.

doi:10.1016/0006-8993(82)90914-3

Cited by 27 publications

(6 citation statements)

References 11 publications

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“…The simplest interpretation of our results is that the electrical shocks activate a small fascicle of efferent axons whose peripheral course is not coincident with the auditory afferents (see Methods). This view is supported by anatomical evidence that confirms the existence of an efferent innervation to the turtle cochlea (Strutz, 1982) with the hair cells as the likely targets (Miller, 1978). A weakness of our experimental approach is that we are delivering shocks to many efferent fibres simultaneously.…”

Section: Discussionmentioning

confidence: 71%

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Efferent desensitization of auditory nerve fibre responses in the cochlea of the turtle Pseudemys scripta elegans.

Art

Fettiplace

1984

The Journal of Physiology

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SUMMARY1. Extracellular recordings were made from single auditory afferents in the isolated half-head of the turtle, and changes in their acoustic sensitivity were examined following electrical stimulation of the efferent fibres to the basilar papilla.2. Short trains of efferent shocks caused a prolonged elevation of the pure tone thresholds of the auditory afferents and an abolition of their spontaneous activity. These changes could be demonstrated in a majority of recordings and without antidromic firing of the afferent.3. The amount of desensitization increased steeply with shock number and a train of ten closely spaced shocks could elevate the threshold at the most sensitive or characteristic frequency by four orders of magnitude. Desensitization also occurred with single efferent shocks at repetition frequencies exceeding 25/s. 4. Discharge rate versus sound pressure functions were constructed for a number of afferents. The maximum slope of the functions, and the saturated firing rates were both reduced by efferent stimulation; there was also an over-all shift of the rate-intensity function to higher stimulus levels. Such effects would enable the afferent to signal a wider range of sound pressures.5. Efferent stimulation caused a broadening of the afferent frequency-threshold curves by removal of the narrowly-tuned region around the characteristic frequency. We suggest that the loss in tuning and concomitant improvement in temporal resolution may be a functionally important consequence of efferent action.

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Section: Discussionmentioning

confidence: 71%

“…The existence of reciprocal synapses has been described in the amphibian vestibular system (Dunn, 1980 (Strutz, 1982) with the hair cells as the likely targets (Miller, 1978). A weakness of our experimental approach is that we are delivering shocks to many efferent fibres simultaneously.…”

Section: Efferent Inhibition Offrequency 8electivitymentioning

confidence: 98%

Efferent desensitization of auditory nerve fibre responses in the cochlea of the turtle Pseudemys scripta elegans.

Art

Fettiplace

1984

The Journal of Physiology

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“…In retrospect, the difficulty in determining their precise anatomical location was due in part to the surprisingly small number of cell bodies and the lack of robust neuronal tracing techniques. With the use of HRP, however, the location of vestibular efferent neuron cell bodies was subsequently identified in a number of mammalian and nonmammalian species, including fish (Highstein and Baker 1986), amphibians (Pellegrini et al 1985), reptiles (Strutz 1982), birds (Eden and Correia 1982), rodents (Perachio and Kevetter 1989), cats (Dechesne et al 1984;Gacek and Lyon 1974), and primates (Goldberg and Fernández 1980). These studies consistently revealed a small number of neurons in the brain stem, at approximately the same level as the other vestibular nuclei.…”

Section: Vestibular Efferent Anatomymentioning

confidence: 99%

A review of efferent cholinergic synaptic transmission in the vestibular periphery and its functional implications

Poppi

Holt

Lim

et al. 2020

Journal of Neurophysiology

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It has been over 60 years since peripheral efferent vestibular terminals were first identified in mammals, and yet the function of the efferent vestibular system remains obscure. One reason for the lack of progress may be due to our deficient understanding of the peripheral efferent synapse. Although vestibular efferent terminals were identified as cholinergic less than a decade after their anatomical characterization, the cellular mechanisms that underlie the properties of these synapses have had to be inferred. In this review we examine how recent mammalian studies have begun to reveal both nicotinic and muscarinic effects at these terminals and therefore provide a context for fast and slow responses observed in classic electrophysiological studies of the mammalian efferent vestibular system, nearly 40 years ago. Although incomplete, these new results together with those of recent behavioral studies are helping to unravel the mysterious and perplexing action of the efferent vestibular system. Armed with this information, we may finally appreciate the behavioral framework in which the efferent vestibular system operates.

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“…These neu- rons were only observed ipsilateral to the injection site. Most likely, these cells were retrogradely labeled efferent acoustic/vestibular neurons that have been previously described in turtles [Strutz, 1982;Powers and Reiner, 1993].…”

Section: Posterior Eighth Nerve Injectionsmentioning

confidence: 99%

Central Trigeminal and Posterior Eighth Nerve Projections in the Turtle <i>Chrysemys picta</i> Studied in vitro

Herrick

Keifer²

1998

Brain Behav Evol

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Recent electrophysiological studies in the turtle Chrysemys picta have suggested that a neural correlate of the eye-blink reflex can be evoked in an in vitro brainstem-cerebellum preparation by electrical rather than natural stimulation of the cranial nerves. Discharge recorded in the abducens nerve, which is similar to EMG recordings from extraocular muscles during eye retraction, is triggered by a brief electrical stimulus applied to the ipsilateral trigeminal nerve. Evidence also suggests that pairing a one-second electrical stimulus applied to the posterior eighth nerve immediately prior to a single shock to the trigeminal nerve results in classically conditioned abducens nerve discharge in response to the previously neutral eighth nerve stimulus. In view of these physiological findings, the aim of the present study was to examine the central projections of trigeminal and posterior eighth nerve inputs to elucidate the anatomical substrates that may underlie the in vitro eye-blink reflex and possible pathways involved in reflex conditioning. Neurobiotin (NB) or fluorescein dextran (FD) was pressure injected into the cut end of either the trigeminal or posterior eighth nerve of the in vitro brainstem-cerebellum. Following trigeminal nerve injections, both tracers showed label in the ipsilateral trigeminal nuclear complex. Direct projections to the ipsilateral principal and accessory abducens motor nuclei were observed, suggesting that the eye-blink reflex is monosynaptic. Trigeminal nerve axons were also observed to terminate in the ipsilateral cerebellar cortex. The results of the posterior eighth nerve injections showed axonal projections and terminals in the cochlear, vestibular and principal sensory trigeminal nuclei. Terminal label was also observed in the ipsilateral cerebellar cortex, deep cerebellar nuclei, and in the principal and accessory abducens motor nuclei. Results from the NB cases suggested transneuronal transport of this tracer substance, whereas the FD cases did not. The present findings suggest that convergence of trigeminal and posterior eighth nerve inputs occurs in the ipsilateral cerebellar cortex, the principal sensory trigeminal nucleus, and the principal and accessory abducens motor nuclei. These regions of convergence may therefore be considered as potential sites of synaptic modification during in vitro studies of the conditioned abducens nerve reflex.

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The origin of efferent fibers to the inner ear in a turtle (Terrapene ornata). A horseradish peroxidase study

Cited by 27 publications

References 11 publications

Efferent desensitization of auditory nerve fibre responses in the cochlea of the turtle Pseudemys scripta elegans.

Efferent desensitization of auditory nerve fibre responses in the cochlea of the turtle Pseudemys scripta elegans.

A review of efferent cholinergic synaptic transmission in the vestibular periphery and its functional implications

Central Trigeminal and Posterior Eighth Nerve Projections in the Turtle <i>Chrysemys picta</i> Studied in vitro

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