Responses to species-specific vocalizations in the auditory cortex of awake and anesthetized guinea pigs

Syka, Josef; Šuta, Daniel; Popelář, Jiří

doi:10.1016/j.heares.2005.01.013

Cited by 61 publications

(55 citation statements)

References 26 publications

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“…Ketamine, which was used to anesthetize the animals in our experiments, has been shown to alter the spontaneous firing rate and stimulus-driven activity (rate and temporal pattern) in the auditory cortex (Syka et al 2005;Zurita et al 1994). Changes in frequency coding properties have also been observed under anesthesia Ostwald 2001, 2003).…”

Section: Discussionmentioning

confidence: 74%

Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

Lim¹,

Anderson²

2007

Journal of Neurophysiology

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. Auditory cortical responses to electrical stimulation of the inferior colliculus: implications for an auditory midbrain implant. J Neurophysiol 96: 975-988, 2006. First published May 24, 2006 doi:10.1152/jn.01112.2005. The success and limitations of cochlear implants (CIs) along with recent advances in deep brain stimulation and neural engineering have motivated the development of a central auditory prosthesis. In this study, we investigated the effects of electrical stimulation of the inferior colliculus central nucleus (ICC) on primary auditory cortex (A1) activity to determine the potential benefits of an auditory midbrain implant (AMI). We recorded multiunit activity in A1 of ketamine-anesthetized guinea pigs in response to single-pulse (200 s/phase) monopolar stimulation of the ICC using multisite silicon-substrate probes. We then compared measures of threshold, dynamic range, and tonotopic spread of activation for ICC stimulation with that of published data for CI stimulation. Our results showed that compared with cochlear stimulation, ICC stimulation achieved: 1) thresholds about 8 dB lower; 2) dynamic ranges Ն4 dB greater; and 3) more localized, frequency-specific activation, even though frequency specificity was partially lost at higher stimulus levels for low-frequency ICC regions. Our results also showed that stimulation of rostral ICC regions elicited lower thresholds but with greater activation spread along the tonotopic gradient of A1 than did stimulation of more caudal regions. These results suggest that an AMI may improve frequency and level coding with lower energy requirements compared with CIs. However, a trade-off between lower perceptual thresholds and better frequency discrimination may exist that depends on location of stimulation along the caudorostral dimension of the ICC. Overall, this study provides the foundation for future AMI research and development.

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Section: Discussionmentioning

confidence: 74%

Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

Lim¹,

Anderson²

2007

Journal of Neurophysiology

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“…The AC is very susceptible to anesthesia. Response properties of A1 neurons in rodent are changed profoundly by application of Equithesin, urethane, or ketamine (Gaese and Ostwald, 2001;Cotillon-Williams and Edeline, 2003;Syka et al, 2005). Different anesthetics can exert a variety of effects on auditory cortical neurons resulting in, for example, threshold changes (Cheung et al, 2001), altered spontaneous rate (Zurita et al, 1994), or evoked oscillations (Cotillon-Williams and Edeline, 2003).…”

Section: Role Of Cortical Statementioning

confidence: 99%

Correlating Stimulus-Specific Adaptation of Cortical Neurons and Local Field Potentials in the Awake Rat

Behrens¹,

Bäuerle²,

Kössl³

et al. 2009

J. Neurosci.

161

128

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Changes in the sensory environment are good indicators for behaviorally relevant events and strong triggers for the reallocation of attention. In the auditory domain, violations of a pattern of repetitive stimuli precipitate in the event-related potentials as mismatch negativity (MMN). Stimulus-specific adaptation (SSA) of single neurons in the auditory cortex has been proposed to be the cellular substrate of MMN (Nelken and Ulanovsky, 2007). However, until now, the existence of SSA in the awake auditory cortex has not been shown. In the present study, we recorded single and multiunits in parallel with evoked local field potentials (eLFPs) in the primary auditory cortex of the awake rat. Both neurons and eLFPs in the awake animal adapted in a stimulus-specific manner, and SSA was controlled by stimulus probability and frequency separation. SSA of isolated units was significant during the first stimulus-evoked "on" response but not in the following inhibition and rebound of activity. The eLFPs exhibited SSA in the first negative deflection and, to a lesser degree, in a slower positive deflection but no MMN. Spike adaptation correlated closely with adaptation of the fast negative deflection but not the positive deflection. Therefore, we conclude that single neurons in the auditory cortex of the awake rat adapt in a stimulus-specific manner and contribute to corresponding changes in eLFP but do not generate a late deviant response component directly equivalent to the human MMN. Nevertheless, the described effect may reflect a certain part of the process needed for sound discrimination.

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“…This is not to claim that auditory coding is the same at the level of the midbrain as in the cochlea. However, there is evidence from animal studies suggesting that some general coding features of complex sound (e.g., to varying pitch or animal vocalizations) are maintained, to some extent, from the cochlea up to the auditory cortex (Cariani & Delgutte, 1996;Suta, Kvasnak, Popelar, & Syka, 2003;Syka, Suta, & Popelar, 2005;Wang, Merzenich, Beitel, & Schreiner, 1995). In particular, many neurons still respond in synchrony to the envelope of the sound signal and with a spatial representation for frequency information at the level of the midbrain as occur within the cochlea (Joris, Schreiner, & Rees, 2004;Krishna & Semple, 2000).…”

Section: Patient Fitting and Psychophysical Findingsmentioning

confidence: 99%

Auditory Midbrain Implant: A Review

Lim

Lenarz

2009

Trends in Amplification

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The auditory midbrain implant (AMI) is a new hearing prosthesis designed for stimulation of the inferior colliculus in deaf patients who cannot sufficiently benefit from cochlear implants. The authors have begun clinical trials in which five patients have been implanted with a single shank AMI array (20 electrodes). The goal of this review is to summarize the development and research that has led to the translation of the AMI from a concept into the first patients. This study presents the rationale and design concept for the AMI as well a summary of the animal safety and feasibility studies that were required for clinical approval. The authors also present the initial surgical, psychophysical, and speech results from the first three implanted patients. Overall, the results have been encouraging in terms of the safety and functionality of the implant. All patients obtain improvements in hearing capabilities on a daily basis. However, performance varies dramatically across patients depending on the implant location within the midbrain with the best performer still not able to achieve open set speech perception without lip-reading cues. Stimulation of the auditory midbrain provides a wide range of level, spectral, and temporal cues, all of which are important for speech understanding, but they do not appear to sufficiently fuse together to enable open set speech perception with the currently used stimulation strategies. Finally, several issues and hypotheses for why current patients obtain limited speech perception along with several feasible solutions for improving AMI implementation are presented.

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Responses to species-specific vocalizations in the auditory cortex of awake and anesthetized guinea pigs

Cited by 61 publications

References 26 publications

Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

Correlating Stimulus-Specific Adaptation of Cortical Neurons and Local Field Potentials in the Awake Rat

Auditory Midbrain Implant: A Review

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