Brain Stem Responses Evoked by Stimulation of the Mature Cochlear Nucleus With an Auditory Brain Stem Implant

✓ Intracranial responses from the auditory nerve and the cochlear nucleus were recorded from patients undergoing neurosurgical operations during which these structures were exposed. Responses to stimulation of the ipsilateral ear with short tonebursts from the vicinity of the cochlear nucleus show a large surface-negative peak, the latency of which is close to that of peak III in the auditory brain-stem evoked potentials recorded from scalp electrodes. There was also a response to contralateral stimulation, smaller in amplitude and with a longer latency. It is concluded that the cochlear nucleus is the main generator of peak III responses, and that structures of the ascending auditory pathway that are more central than the cochlear nucleus are unlikely to contribute to wave III of the auditory brain-stem evoked potentials.

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Inferior Colliculus Responses to Multichannel Microstimulation of the Ventral Cochlear Nucleus: Implications for Auditory Brain Stem Implants

Journal of Neurophysiology ◽

10.1152/jn.00629.2007 ◽

2008 ◽

Vol 99 (1) ◽

pp. 1-13 ◽

Cited By ~ 16

Author(s):

Mohit N. Shivdasani ◽

Stefan J. Mauger ◽

Graeme D. Rathbone ◽

Antonio G. Paolini

Keyword(s):

Electrical Stimulation ◽

Brain Stem ◽

Inferior Colliculus ◽

Cochlear Nucleus ◽

Electrode Placement ◽

Ventral Cochlear Nucleus ◽

Frequency Specificity ◽

Auditory Brain Stem ◽

Acoustic Tuning ◽

Stimulation Of

Multichannel techniques were used to assess the frequency specificity of activation in the central nucleus of the inferior colliculus (CIC) produced by electrical stimulation of localized regions within the ventral cochlear nucleus (VCN). Data were recorded in response to pure tones from 141 and 193 multiunit clusters in the rat VCN and the CIC, respectively. Of 141 VCN sites, 126 were individually stimulated while recording responses in the CIC. A variety of CIC response types were seen with an increase in both electrical and acoustic stimulation levels. The majority of sites exhibited monotonic rate-level types acoustically, whereas spike rate saturation was achieved predominantly with electrical stimulation. In 20.6% of the 364 characteristic frequency aligned VCN–CIC pairs, the CIC sites did not respond to stimulation. In 26% of the 193 CIC sites, a high correlation was observed between acoustic tuning and electrical tuning obtained through VCN stimulation. A high degree of frequency specificity was found in 58% of the 118 lowest threshold VCN–CIC pairs. This was dependent on electrode placement within the VCN because a higher degree of frequency specificity was achieved with stimulation of medial, central, and posterolateral VCN regions than more anterolateral regions. Broadness of acoustic tuning in the CIC played a role in frequency-specific activation. Narrowly tuned CIC sites showed the lowest degree of frequency specificity on stimulation of the anterolateral VCN regions. These data provide significant implications for auditory brain stem implant electrode placement, current localization, power requirements, and facilitation of information transfer to higher brain centers.

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Electrical stimulation of the auditory brain stem structure in deafened adults

The Journal of Rehabilitation Research and Development ◽

10.1682/jrrd.1987.07.0009 ◽

1987 ◽

Vol 24 (3) ◽

pp. 9 ◽

Cited By ~ 58

Author(s):

Laurie S. Eisenberg ◽

Albert A. Maltan ◽

Franco Portillo ◽

Phil Mobley ◽

William F. House

Keyword(s):

Electrical Stimulation ◽

Brain Stem ◽

Auditory Brain Stem ◽

Stem Structure ◽

Stimulation Of

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Spike threshold adaptation diversifies neuronal operating modes in the auditory brain stem

Journal of Neurophysiology ◽

10.1152/jn.00234.2019 ◽

2019 ◽

Vol 122 (6) ◽

pp. 2576-2590

Author(s):

Susan T. Lubejko ◽

Bertrand Fontaine ◽

Sara E. Soueidan ◽

Katrina M. MacLeod

Keyword(s):

Sodium Channel ◽

Brain Stem ◽

Cochlear Nucleus ◽

Fine Tuning ◽

Threshold Dynamics ◽

Spike Threshold ◽

Operating Modes ◽

Auditory Brain Stem ◽

Spike Initiation ◽

Nucleus Angularis

Single neurons function along a spectrum of neuronal operating modes whose properties determine how the output firing activity is generated from synaptic input. The auditory brain stem contains a diversity of neurons, from pure coincidence detectors to pure integrators and those with intermediate properties. We investigated how intrinsic spike initiation mechanisms regulate neuronal operating mode in the avian cochlear nucleus. Although the neurons in one division of the avian cochlear nucleus, nucleus magnocellularis, have been studied in depth, the spike threshold dynamics of the tonically firing neurons of a second division of cochlear nucleus, nucleus angularis (NA), remained unexplained. The input-output functions of tonically firing NA neurons were interrogated with directly injected in vivo-like current stimuli during whole cell patch-clamp recordings in vitro. Increasing the amplitude of the noise fluctuations in the current stimulus enhanced the firing rates in one subset of tonically firing neurons (“differentiators”) but not another (“integrators”). We found that spike thresholds showed significantly greater adaptation and variability in the differentiator neurons. A leaky integrate-and-fire neuronal model with an adaptive spike initiation process derived from sodium channel dynamics was fit to the firing responses and could recapitulate >80% of the precise temporal firing across a range of fluctuation and mean current levels. Greater threshold adaptation explained the frequency-current curve changes due to a hyperpolarized shift in the effective adaptation voltage range and longer-lasting threshold adaptation in differentiators. The fine-tuning of the intrinsic properties of different NA neurons suggests they may have specialized roles in spectrotemporal processing. NEW & NOTEWORTHY Avian cochlear nucleus angularis (NA) neurons are responsible for encoding sound intensity for sound localization and spectrotemporal processing. An adaptive spike threshold mechanism fine-tunes a subset of repetitive-spiking neurons in NA to confer coincidence detector-like properties. A model based on sodium channel inactivation properties reproduced the activity via a hyperpolarized shift in adaptation conferring fluctuation sensitivity.

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An in vivo investigation of inferior colliculus single neuron responses to cochlear nucleus pulse train stimulation

Journal of Neurophysiology ◽

10.1152/jn.01087.2011 ◽

2012 ◽

Vol 108 (11) ◽

pp. 2999-3008 ◽

Cited By ~ 2

Author(s):

Stefan J. Mauger ◽

Mohit N. Shivdasani ◽

Graeme D. Rathbone ◽

Antonio G. Paolini

Keyword(s):

Speech Perception ◽

Brain Stem ◽

Inferior Colliculus ◽

Cochlear Nucleus ◽

Acoustic Stimulation ◽

Neural Firing ◽

Response Properties ◽

Stimulus Rate ◽

Auditory Brain Stem

The auditory brain stem implant (ABI) is being used clinically to restore hearing to patients unable to benefit from a cochlear implant (CI). Speech perception outcomes for ABI users are typically poor compared with most CI users. The ABI is implanted either on the surface of or penetrating through the cochlear nucleus in the auditory brain stem and uses stimulation strategies developed for auditory nerve stimulation with a CI. Although the stimulus rate may affect speech perception outcomes with current stimulation strategies, no studies have systematically investigated the effect of stimulus rate electrophysiologically or clinically. We therefore investigated rate response properties and temporal response properties of single inferior colliculus (IC) neurons from penetrating ABI stimulation using stimulus rates ranging from 100 to 1,600 pulses/s in the rat. We found that the stimulus rate affected the proportion of response types, thresholds, and dynamic ranges of IC activation. The stimulus rate was also found to affect the temporal properties of IC responses, with higher rates providing more temporally similar responses to acoustic stimulation. Suppression of neural firing and inhibition in IC neurons was also found, with response properties varying with the stimulus rate. This study demonstrated that changes in the ABI stimulus rate results in significant differences in IC neuron response properties. Due to electrophysiological differences, the stimulus rate may also change perceptual properties. We suggest that clinical evaluation of the ABI stimulus rate should be performed.

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Auditory brain-stem evoked potentials in cat after kainic acid induced neuronal loss. II. Cochlear nucleus

Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section ◽

10.1016/0168-5597(91)90092-c ◽

1991 ◽

Vol 80 (5) ◽

pp. 436-445 ◽

Cited By ~ 29

Author(s):

Menashe Zaaroor ◽

Arnold Starr

Keyword(s):

Evoked Potentials ◽

Brain Stem ◽

Kainic Acid ◽

Cochlear Nucleus ◽

Neuronal Loss ◽

Auditory Brain Stem

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Target-specific regulation of presynaptic release properties at auditory nerve terminals in the avian cochlear nucleus

Journal of Neurophysiology ◽

10.1152/jn.00752.2015 ◽

2016 ◽

Vol 115 (3) ◽

pp. 1679-1690 ◽

Cited By ~ 1

Author(s):

J. Ahn ◽

K. M. MacLeod

Keyword(s):

Brain Stem ◽

Cochlear Nucleus ◽

Auditory Nerve ◽

Auditory Information ◽

Nerve Terminals ◽

Release Probability ◽

Auditory Brain Stem ◽

Presynaptic Release ◽

Specific Regulation ◽

Synaptic Dynamics

Short-term synaptic plasticity (STP) acts as a time- and firing rate-dependent filter that mediates the transmission of information across synapses. In the auditory brain stem, the divergent pathways that encode acoustic timing and intensity information express differential STP. To investigate what factors determine the plasticity expressed at different terminals, we tested whether presynaptic release probability differed in the auditory nerve projections to the two divisions of the avian cochlear nucleus, nucleus angularis (NA) and nucleus magnocellularis (NM). Estimates of release probability were made with an open-channel blocker of N-methyl-d-aspartate (NMDA) receptors. Activity-dependent blockade of NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) with application of 20 μM (+)-MK801 maleate was more rapid in NM than in NA, indicating that release probability was significantly higher at terminals in NM. Paired-pulse ratio (PPR) was tightly correlated with the blockade rate at terminals in NA, suggesting that PPR was a reasonable proxy for relative release probability at these synapses. To test whether release probability was similar across convergent inputs onto NA neurons, PPRs of different nerve inputs onto the same postsynaptic NA target neuron were measured. The PPRs, as well as the plasticity during short trains, were tightly correlated across multiple inputs, further suggesting that release probability is coordinated at auditory nerve terminals in a target-specific manner. This highly specific regulation of STP in the auditory brain stem provides evidence that the synaptic dynamics are tuned to differentially transmit the auditory information in nerve activity into parallel ascending pathways.

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