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Brain Stimulation 2023Transcranial ultrasound stimulation (TUS) is a promising noninvasive neuromodulation modality. The inadvertent and unpredictable activation of the auditory system in...
BACKGROUND
Transcranial ultrasound stimulation (TUS) is a promising noninvasive neuromodulation modality. The inadvertent and unpredictable activation of the auditory system in response to TUS obfuscates the interpretation of non-auditory neuromodulatory responses.
OBJECTIVE
The objective was to develop and validate a computational metric to quantify the susceptibility to unintended auditory brainstem response (ABR) in mice premised on time frequency analyses of TUS signals and auditory sensitivity.
METHODS
Ultrasound pulses with varying amplitudes, pulse repetition frequencies (PRFs), envelope smoothing profiles, and sinusoidal modulation frequencies were selected. Each pulse's time-varying frequency spectrum was differentiated across time, weighted by the mouse hearing sensitivity, then summed across frequencies. The resulting time-varying function, computationally predicting the ABR, was validated against experimental ABR in mice during TUS with the corresponding pulse.
RESULTS
There was a significant correlation between experimental ABRs and the computational predictions for 19 TUS signals (R = 0.97).
CONCLUSIONS
To reduce ABR in mice during in vivo TUS studies, 1) reduce the amplitude of a rectangular continuous wave envelope, 2) increase the rise/fall times of a smoothed continuous wave envelope, and/or 3) change the PRF and/or duty cycle of a rectangular or sinusoidal pulsed wave to reduce the gap between pulses and increase the rise/fall time of the overall envelope. This metric can aid researchers performing in vivo mouse studies in selecting TUS signal parameters that minimize unintended ABR. The methods for developing this metric can be adapted to other animal models.
Topics: Mice; Animals; Evoked Potentials, Auditory, Brain Stem; Auditory Threshold; Hearing; Acoustic Stimulation
PubMed: 37690602
DOI: 10.1016/j.brs.2023.09.004 -
PloS One 2021To investigate the effect of systemic administration of salicylate as a tinnitus inducing drug in the auditory cortex of guinea pigs.
OBJECTIVE
To investigate the effect of systemic administration of salicylate as a tinnitus inducing drug in the auditory cortex of guinea pigs.
METHODS
Extracellular recording of spikes of the primary auditory cortex and dorsocaudal areas in healthy male albino Hartley guinea pigs was continuously performed (pre- and post-salicylate).
RESULTS
We recorded 160 single units in the primary auditory cortex from five guinea pigs and 156 single units in the dorsocaudal area from another five guinea pigs. The threshold was significantly elevated after the administration of salicylate in both the primary auditory cortex and dorsocaudal areas. The Q10dB value was significantly increased in the primary auditory cortex, whereas it has significantly decreased in the dorsocaudal area. Spontaneous firing activity was significantly decreased in the primary auditory cortex, whereas it has significantly increased in the dorsocaudal area.
CONCLUSION
Salicylate induces significant changes in single units of both stimulated and spontaneous activity in the auditory cortex of guinea pigs. The spontaneous activity changed differently depending on its cortical areas, which may be due to the neural elements that generate tinnitus.
Topics: Action Potentials; Animals; Auditory Cortex; Auditory Threshold; Guinea Pigs; Salicylic Acid; Software
PubMed: 34762664
DOI: 10.1371/journal.pone.0259055 -
Trends in Hearing 2023Older people often show auditory temporal processing deficits and speech-in-noise intelligibility difficulties even when their audiogram is clinically normal. The causes...
Older people often show auditory temporal processing deficits and speech-in-noise intelligibility difficulties even when their audiogram is clinically normal. The causes of such problems remain unclear. Some studies have suggested that for people with normal audiograms, age-related hearing impairments may be due to a cognitive decline, while others have suggested that they may be caused by cochlear synaptopathy. Here, we explore an alternative hypothesis, namely that age-related hearing deficits are associated with decreased inhibition. For human adults (N = 30) selected to cover a reasonably wide age range (25-59 years), with normal audiograms and normal cognitive function, we measured speech reception thresholds in noise (SRTNs) for disyllabic words, gap detection thresholds (GDTs), and frequency modulation detection thresholds (FMDTs). We also measured the rate of growth (slope) of auditory brainstem response wave-I amplitude with increasing level as an indirect indicator of cochlear synaptopathy, and the interference inhibition score in the Stroop color and word test (SCWT) as a proxy for inhibition. As expected, performance in the auditory tasks worsened (SRTNs, GDTs, and FMDTs increased), and wave-I slope and SCWT inhibition scores decreased with ageing. Importantly, SRTNs, GDTs, and FMDTs were not related to wave-I slope but worsened with decreasing SCWT inhibition. Furthermore, after partialling out the effect of SCWT inhibition, age was no longer related to SRTNs or GDTs and became less strongly related to FMDTs. Altogether, results suggest that for people with normal audiograms, age-related deficits in auditory temporal processing and speech-in-noise intelligibility are mediated by decreased inhibition rather than cochlear synaptopathy.
Topics: Adult; Humans; Aged; Middle Aged; Auditory Threshold; Cochlea; Hearing; Auditory Perception; Presbycusis; Evoked Potentials, Auditory, Brain Stem; Speech Perception
PubMed: 37956654
DOI: 10.1177/23312165231213191 -
Brazilian Journal of Otorhinolaryngology 2015One of the problems observed in pure-tone audiometry tonal has been the variation in test results of a same individual, particularly at frequencies of 4kHz, 6kHz and/or... (Comparative Study)
Comparative Study
INTRODUCTION
One of the problems observed in pure-tone audiometry tonal has been the variation in test results of a same individual, particularly at frequencies of 4kHz, 6kHz and/or 8kHz. Improper placement of headphones is one of the factors that can cause alterations in results.
OBJECTIVE
To compare differences in auditory thresholds using earphones positioned by the examiner and by the worker.
METHODS
Clinical and experimental study conducted in 2009, with 324 workers aged between 19 and 61 years, with a mean of 33.29 years and mean exposure time of 7.67 years. All subjects were familiar with audiometry procedures. Auditory thresholds were obtained at frequencies of 0.25-8kHz, with earphones positioned by the examiners, and at frequencies of 4, 6 and 8kHz, with earphones placed by workers in a comfortable position, following the examiner's instructions. The thresholds obtained in these two situations were compared.
RESULTS
The three frequencies exhibited better responses with earphones placed by the workers themselves (p<0.001). At a frequency of 8kHz a greater difference was found (p<0.001), with a mean of 13.89dB and standard deviation of 6.07dB.
CONCLUSION
Earphone placement by the workers themselves under supervision of the examiner results in improved mean auditory thresholds at frequencies of 4, 6 and 8kHz, the last one significantly higher than the other two.
Topics: Adult; Audiometry, Pure-Tone; Auditory Perception; Auditory Threshold; Brazil; Female; Humans; Male; Middle Aged; Occupational Diseases; Occupational Health
PubMed: 26454532
DOI: 10.1016/j.bjorl.2015.08.016 -
The Journal of International Advanced... Nov 2023The aim of this study is to evaluate the clinical characteristics and electrophysiological changes in patients with different degrees of noise-induced hearing loss...
BACKGROUND
The aim of this study is to evaluate the clinical characteristics and electrophysiological changes in patients with different degrees of noise-induced hearing loss compared with those of normal controls to elucidate the progression of auditory neural damage attributed to noise exposure.
METHODS
A retrospective cohort study was conducted through a review of the medical records for the patients who presented to a tertiary referral center. Sixty-nine participants were included in the study: 29 had noise-induced hearing loss, and 40 were healthy controls. All the participants underwent electrophysiological tests and pure-tone audiometry.
RESULTS
Nine patients showed mild hearing loss (mild hearing loss group), while the others showed worse than moderate hearing loss on puretone audiometry (severe hearing loss group). Significantly reduced wave I and V amplitudes of auditory brainstem response were present in both mild and severe hearing loss groups compared to the control group (P -lt; .001 and P=.002, respectively), without significant differences between the mild and severe hearing loss groups. In the multivariate analysis, auditory brainstem response wave V amplitude was negatively associated with auditory brainstem response wave I-V inter-peak latency delay (B=-0.48, P=.02).
CONCLUSION
The results of the present study confirm the similarity in the electrophysiological characteristics between the mild and severe hearing loss groups. Thus, widespread disruption in the auditory neural conduction could have been established in the early period when the patient developed mild hearing loss following noise exposure.
Topics: Humans; Audiometry, Pure-Tone; Auditory Threshold; Deafness; Evoked Potentials, Auditory, Brain Stem; Hearing Loss, Noise-Induced; Retrospective Studies
PubMed: 38088321
DOI: 10.5152/iao.2023.231192 -
The Journal of Neuroscience : the... Jun 2018Auditory nerve fibers (ANFs) encode pure tones through two modes of coding, spike time and spike rate, depending on the tone frequency. In response to a low-frequency...
Auditory nerve fibers (ANFs) encode pure tones through two modes of coding, spike time and spike rate, depending on the tone frequency. In response to a low-frequency tone, ANF firing is phase locked to the sinusoidal waveform. Because time coding vanishes with an increase in the tone frequency, high-frequency tone coding relies on the spike rate of the ANFs. Adding a continuous broadband noise to a tone compresses the rate intensity function of ANFs and shifts its dynamic range toward higher intensities. Therefore, the ANFs with high-threshold/low-spontaneous rate (SR) are thought to contribute to behavioral tone detection in noise. However, this theory relies on the discharge rate of the ANFs. The direct comparison with the masking threshold through spike timing, irrespective of the spontaneous rate, has not so far been investigated. Taking advantage of a unique proxy to quantify the spike synchrony (i.e., the shuffle autocorrelogram), we show in female gerbils that high-SR ANFs are more adapted to encode low-frequency thresholds through temporal code, giving them a strong robustness in noise. By comparing behavioral thresholds measured using prepulse inhibition of the acoustical startle reflex with population thresholds calculated from ANFs pooled per octave band, we show that threshold-based spike timing provides a better estimate of behavioral thresholds in the low-frequency range, whereas the high-frequency behavioral thresholds rely on the spiking rate, particularly in noise. This emphasizes the complementarity of temporal and rate modes to code tone-in-noise thresholds over a large range of frequencies. There is a general agreement that high-threshold/low-spontaneous rate (SR) auditory nerve fibers (ANFs) are of prime importance for tone detection in noise. However, this theory is based on the discharge rate of the fibers. Comparing the behavioral thresholds and single ANF thresholds shows that this is only true in the high-frequency range of tone stimulations. In the low-frequency range of tones (up to 2.7 kHz in the gerbil), the most sensitive ANFs (high-SR fibers) carry neural information through a spike-timing mode, even for noise in which tones do not induce a noticeable increment in the spike rate. This emphasizes the interplay between spike-time and spike-rate modes in the auditory nerve to encode tone-in-noise threshold over a large range of tone frequencies.
Topics: Acoustic Stimulation; Animals; Auditory Perception; Auditory Threshold; Female; Gerbillinae; Noise
PubMed: 29793977
DOI: 10.1523/JNEUROSCI.3103-17.2018 -
JAMA Otolaryngology-- Head & Neck... Jan 2020
Topics: Auditory Threshold; Hearing; Hearing Tests; Humans
PubMed: 31725835
DOI: 10.1001/jamaoto.2019.3372 -
Journal of Visualized Experiments : JoVE Dec 2022Many reports in the last 15 years have assessed changes in the auditory brainstem response (ABR) waveform after insults such as noise exposure. Common changes include...
Many reports in the last 15 years have assessed changes in the auditory brainstem response (ABR) waveform after insults such as noise exposure. Common changes include reductions in the peak 1 amplitude and the relative latencies of the later peaks, as well as increased central gain, which is reflected by a relative increase in the amplitudes of the later peaks compared to the amplitude of peak 1. Many experimenters identify the peaks and troughs visually to assess their relative heights and latencies, which is a laborious process when the waveforms are collected in 5 dB increments throughout the hearing range for each frequency and condition. This paper describes free routines that may be executed in the open-source platform R with the RStudio interface to semi-automate the measurements of the peaks and troughs of auditory brainstem response (ABR) waveforms. The routines identify the amplitudes and latencies of peaks and troughs, display these on a generated waveform for inspection, collate and annotate the results into a spreadsheet for statistical analysis, and generate averaged waveforms for figures. In cases when the automated process misidentifies the ABR waveform, there is an additional tool to assist in correction. The goal is to reduce the time and effort needed to analyze the ABR waveform so that more researchers will include these analyses in the future.
Topics: Evoked Potentials, Auditory, Brain Stem; Hearing; Hearing Tests; Reaction Time; Motivation; Auditory Threshold; Acoustic Stimulation
PubMed: 36571417
DOI: 10.3791/64737 -
BMJ Open May 2023Cochlear implantation with hearing preservation (HPCI) has allowed a cochlear implant (CI) electrode to be implanted while trying to preserve residual acoustic...
INTRODUCTION
Cochlear implantation with hearing preservation (HPCI) has allowed a cochlear implant (CI) electrode to be implanted while trying to preserve residual acoustic low-frequency hearing. The concept arises from the importance of this low-frequency information and the limitations of a CI in several auditory domains. The combination of electrical hearing with either preserved acoustic hearing or amplified 'natural' hearing has the potential to address these issues and enable children with HPCI to closely follow normal auditory development.The aim of this study is to evaluate the 'real-life' benefit of preserved acoustic low-frequency hearing in children with a CI, understand the benefits of preserved natural hearing in complex listening situations and so enable parents and children to make an informed choice about implantation. Ultimately, helping to ensure the maximum number of children benefit from this life-changing intervention.
METHODS AND ANALYSIS
Nineteen ears in children and young people aged 6-17 years old with 'successful' HPCI will be subjected to a test battery consisting of: (1) spatial release from masking; (2) complex pitch direction discrimination; (3) melodic identification; (4) perception of prosodic features in speech and (5) threshold equalising noise test. Subjects will be tested in the electro-acoustic stimulation (EAS)/electro-natural stimulation (ENS) and the electric-only (ES) condition, thereby acting as their own control group. Standard demographic and hearing health information will be collected. In the absence of comparable published data to power the study, sample size was determined on pragmatic grounds. Tests are exploratory and for hypothesis-generating purposes. Therefore, the standard criterion of p<0.05 will be used.
ETHICS AND DISSEMINATION
This study has been approved by the Health Research Authority and NHS Research Ethics Committee (REC) within the UK (22/EM/0017). Industry funding was secured via a competitive researcher-led grant application process. Trial results will be subject to publication according to the definition of the outcome presented in this protocol.
Topics: Child; Humans; Adolescent; Cochlear Implantation; Case-Control Studies; Speech Perception; Auditory Threshold; Hearing
PubMed: 37156582
DOI: 10.1136/bmjopen-2022-067248 -
Otology & Neurotology : Official... Apr 2022Describe early hearing preservation (HP) cochlear implantation (CI) outcomes using a new slim lateral wall electrode (SLWE).
OBJECTIVE
Describe early hearing preservation (HP) cochlear implantation (CI) outcomes using a new slim lateral wall electrode (SLWE).
STUDY DESIGN
Prospective cohort study.
SETTING
Tertiary referral center.
PATIENTS
Adult CI candidates with preoperative low-frequency pure-tone average (LFPTA; 125, 250, 500 Hz) ≤60 dB HL.
INTERVENTION
CI with and without intracochlear real-time electrocochleography (RT-ECochG).
MAIN OUTCOME MEASURE
HP (LFPTA ≤80 dB HL), LFPTA shift, speech-perception performance measures, postoperative CT reconstruction.
RESULTS
Forty-two subjects were implanted with the SLWE. Thirty patients underwent full insertion without RT-ECochG feedback, and HP was maintained at 3-months postactivation for 7 (23.3%) patients with mean LFPTA shift of 57.5 ± 25.6 dB HL. RT-ECochG feedback was utilized on 12 patients, of whom 6 patients had full insertions and 6 patients had anywhere from 1 to 3 electrodes left outside of the cochlea based on RT-ECochG feedback. At 3 months postoperatively, HP was achieved on 10 (83.3%) patients and mean LFPTA shift was 18.9 c 11.7 dB HL. Mean difference between LFPTA threshold shift at 3-months postactivation with and without RT-ECochG was 38.6 dB HL (95% CI, 25.6-51.67). There was an improvement in delta CNC from preoperative to 3-months postactivation when using RT-ECochG, with mean difference 20.7% (95% CI, 3.3-38.1).
CONCLUSIONS
Use of RT-ECochG monitoring during SLWE placement results in fewer full electrode insertions and significantly better HP rates and speech-perception outcomes when compared with unmonitored insertions. Further investigation is needed to evaluate long-term audiologic outcomes to better understand the relationships among ECochG, cochlear trauma, functional outcomes, and HP.
Topics: Adult; Audiometry, Evoked Response; Audiometry, Pure-Tone; Auditory Threshold; Cochlear Implantation; Cochlear Implants; Hearing; Humans; Prospective Studies; Treatment Outcome
PubMed: 35170555
DOI: 10.1097/MAO.0000000000003475