Brain-stem Potentials Research Articles

Predicting early auditory evoked potentials using a computational model of auditory-nerve processing.

Non-invasive electrophysiological measures, such as auditory evoked potentials (AEPs), play a crucial role in diagnosing auditory pathology. However, the relationship between AEP morphology and cochlear degeneration remains complex and not well understood. Dau [J. Acoust. Soc. Am. 113, 936-950 (2003)] proposed a computational framework for modeling AEPs that utilized a nonlinear auditory-nerve (AN) model followed by a linear unitary response function. While the model captured some important features of the measured AEPs, it also exhibited several discrepancies in response patterns compared to the actual measurements. In this study, an enhanced AEP modeling framework is presented, incorporating an improved AN model, and the conclusions from the original study were reevaluated. Simulation results with transient and sustained stimuli demonstrated accurate auditory brainstem responses (ABRs) and frequency-following responses (FFRs) as a function of stimulation level, although wave-V latencies remained too short, similar to the original study. When compared to physiological responses in animals, the revised model framework showed a more accurate balance between the contributions of auditory-nerve fibers (ANFs) at on- and off-frequency regions to the predicted FFRs. These findings emphasize the importance of cochlear processing in brainstem potentials. This framework may provide a valuable tool for assessing human AN models and simulating AEPs for various subtypes of peripheral pathologies, offering opportunities for research and clinical applications.

The Effects of Stimulus Repetition Rate on Electrically Evoked Auditory Brainstem Potentials in Postlingually Deafened Adult Cochlear Implant Recipients.

Background: By using outcome prediction scores, it is possible to distinguish between good and poor performers with cochlear implants (CI) after CI implantation. The reasons for poor performance, despite good basic conditions, can be manifold. On the one hand, the postoperative fitting may be inadequate; on the other, neurophysiological disease processes may impair speech understanding with a CI. These disease processes are not yet fully understood. In acoustics, it is known that the auditory brainstem responses (ABR) and their latencies and amplitudes allow differential diagnosis based on reference values for normal-hearing individuals. The aim of this study was to provide reference values for electrically evoked brainstem responses (EABRs) in terms of rate-dependent latencies and amplitudes. Methods: 20 ears of 18 experienced adult CI recipients with a predicted and measured good postoperative word recognition score were recruited from the clinic's patient pool. In the same stimulation mode and intensity we measured latencies and interpeak-latencies of EABRs and electrically evoked compound action potentials (ECAPs). With a defined supra-threshold stimulation intensity above the individual ECAP threshold, we applied stimulation at several rates between 11 and 91 stimuli per second. Results: We found rate dependences for EABR latency t3 and t5 in the order of 0.19 ms and 0.37 ms, respectively, while ECAP was not affected by rate. Correspondingly, the interpeak intervals' rate dependences for t5-t1, t5-t3 and t3-t1 were of the order of 0.37 ms, 0.18 ms and 0.19 ms. Comparing the EABR amplitudes between the stimulation rates 11/s and 81/s, we found that at 81/s the amplitudes were significantly reduced down: to 73% for A3 and 81% for A5. These rate dependences of latency and amplitude in EABR have characteristics comparable to those of acoustic ABR. Conclusions: These data may serve to provide reference values for EABR and ECAP latencies, interpeak intervals and amplitudes with respect to stimulation rate. Altered response patterns of ECAPs and EABRs to normalised stimulation modes could be used in the future to describe and classify neuropathological processes in a better-differentiated way.

Evaluation of an Investigational Hearing Screening Device (HeLe) to Demonstrate Acoustic Brainstem Response among Normal-hearing Adults.

This pilot human trial demonstrates the ability of the investigational newborn hearing screening device to provide acoustic stimulation to produce evoked potentials, as well as its ability to capture and acquire auditory evoked potentials, especially the auditory brainstem response (ABR) wave V. This pilot study also demonstrates the ease of recognizing and identifying ABR waves in the graphical presentation of the evoked potentials over time. Fourteen normal-hearing adults or a total of twenty-eight (28) normal-hearing adult ears underwent auditory brainstem response testing using the investigational hearing screening device. A commercially available auditory brainstem response detection device was used to confirm that the acquired ABR waves of the investigational device are normal. The ABR waves displayed by the investigation device were also reviewed by the clinical audiologists to determine their recognizability and identifiability. The pilot trial demonstrates the ability of the investigational newborn hearing screening device in providing acoustic stimulation to produce evoked potentials, and in acquiring and capturing ABR waves, specifically the wave V, among normal-hearing adult ears. The clinical audiologists recognized and identified the ABR wave V among the evoked potentials at 40dB, 60dB, and 80dB acoustic stimulation. About eighty-nine percent (89.2%) of all ears tested had identifiable and recognizable wave V upon acoustic stimulation at 40dB. The investigational hearing screening device: (1) can provide acoustic stimulation to produce evoked potentials, (2) can accurately capture and acquire these evoked potentials, (3) can present these evoked potentials in a voltage per time graphical display which an audiologist and trained HCP can easily read and interpret (diagnostic ABR), and (4) can present wave V auditory brainstem potentials that can be easily identified by an audiologist and trained HCP (screening ABR).

Simultaneous measurement of human auditory nerve and brainstem potentials: Effects of upward spread of excitation

Acoustic clicks evoke strong synchrony of auditory-nerve (AN) fibers, thereby eliciting a compound action potential (CAP); however, synchrony is reduced by the delay of the cochlear traveling wave. Upward-frequency chirps compensate for this delay, resulting in larger CAPs evoked by chirps than clicks. Our model simulations of CAPs suggest that chirps presented at high intensities (100 dB peSPL) adapt basal AN fibers via upward spread of excitation of low-frequency chirp components. This adaptation results in less-than-or-equal-to CAP amplitudes and distorted CAP morphology compared to CAPs evoked by clicks. Simulations show that these effects on CAP amplitude and morphology can be avoided by reducing the amplitude of the low-frequency components of the chirp (i.e., modified chirp). Here we present CAPs from 12 young adults with NH, which for high stimulus intensities, exhibit reduced amplitudes and broader CAP morphology for chirps than clicks, whereas CAP amplitudes for modified chirps exceed those for clicks, consistent with model simulations. The distorted CAP morphology in response to high-level chirps is consistent with adaptation of AN responses and broad cochlear excitation. Interestingly, the deleterious effects of high-level chirps on CAP amplitude and morphology are reduced or absent in simultaneous recordings of the auditory brainstem response.

Клинико-нейропсихологические особенности церебральной организации подкорковых структур в развитии психических расстройств аутистического спектра у детей

The article deals with the peculiarities of the cerebral organization of subcortical structures in children with autism spectrum disorders. The study involved 48 children aged from 3 to 8 years (M=5.75; SD=2.61) having ICD-10 diagnoses F84.0, F84.1, F84.5. All children underwent registration of acoustic evoked brainstem potentials and neuropsychological examination. The relationship of the indicators of acoustic evoked potentials of the brain stem with the functioning of different blocks of the brain was established: the block of cortical tone and the brain energy block (Block I), the block of reception, processing and storage of exteroceptive information (Block II), the block of programming, regulation and control of the course of mental activity (Block III). For children with difficulties in activation and energy components of activity, perception of auditory information by subcortical structures of the brain causes certain difficulties (difficulties in work of the I block of the brain). Children with difficulties in right hemispheric holistic information processing strategy and a high level of its development are characterized by a reduced level of control over the course of thought activity, with difficulties in automating thinking and speech and difficulties in coordinating movements (difficulties in the work of Block II of the brain). The identified features of the cerebral organization of the processes of perception of auditory information and processes of mental activity in children with autism spectrum disorders are manifested in disorders of the course of thought activity, the function of peripheral receptors and conduction pathways to the cortical centers of the auditory analyzer, in a lowered level of control over the auditory analyzer. In connection with these processes there are difficulties with automatization of thinking and speech, coordination of movements in children.

Opioid modulation of cochlear auditory responses in the rat inner ear.

The auditory system has an extensive efferent innervation, which contributes to processes of control and regulation of the afferent input. The expression of receptors to various neurotransmitters and neuropeptides in the inner ear has been described, among which endogenous opioid receptors are found. The role of opioid receptors in the cochlea is not yet fully defined, it has been reported that opioid agonists and antagonists modulate the response to auditory stimuli and in clinical practice, multiple cases have been reported in which the consumption of opioid derivatives induce sensorineural hearing loss. In this work, we evaluated the effects of acute treatment with morphine, fentanyl, tramadol, and naloxone, in the auditory brain stem potentials (ABR), the compound action potential (CAP), and distortion products otacoustic emissions (DPOAE), across a wide range of stimulus frequencies and amplitudes. Adult Long-Evans rats of the strain CII/ZV weighing 180-220g were used. For the ABR recording drugs were administered intraperitoneally or intravenously. For the CAP and DPOAE drugs were applied by direct perfusion in the middle ear. The opioid agonists produced a consistent increase in the amplitude of the PI component of the ABR and of the N1-P1 amplitude of the CAP. Naloxone produced no significant changes in the ABR and a reduction of the CAP N1-P1 amplitude. Also, opioid agonists induced a decrease in the amplitude of the DPOAE. These results show that the opioid receptor activation modulates both the afferent response at both the afferent response to acoustic stimuli, and also at the cochlear mechanics as revealed by DPOAE changes. These results present a significant step in understanding how opioid modulation of auditory responses may contribute to the auditory processing and to sensorineural hearing loss produced by opioids.

Development of a point of care system for automated coma prognosis: a prospective cohort study protocol

IntroductionComa is a deep state of unconsciousness that can be caused by a variety of clinical conditions. Traditional tests for coma outcome prediction are based mainly on a set of...

Differentiating cochlear synaptopathies into different hearing disorders

Due to demographic change and altered recreational behavior, a rapid increase in hearing deficits is expected in the next 20-30years. Consequently, the risk of age-related loss of speech discrimination, tinnitus, hyperacusis, or-as recently shown-dementia, will also increase. There are increasing indications that the loss of specific hearing fibers in humans and animals is involved in various hearing disorders. This fiber loss can be caused by cochlear synaptopathy or deafferentation and does not necessarily lead to clinically measurable threshold changes. Animal experiments have shown that reduced auditory nerve activity due to acoustic trauma or aging can be centrally compensated by disproportionately elevated and faster auditory brainstem responses (ABR). The analysis of the suprathreshold amplitudes of auditory evoked brain stem potentials and their latency in combination with non-invasive imaging techniques such as magnetic resonance imaging can help to identify the central compensatory ability of subjects and to assign defined hearing deficits.

Electrically Evoked Auditory Brainstem Response over Round Window by Bipolar Stimulation

Auditory brainstem potentials can be elicited by electrical stimulation of the round window (RW). In this technique, extracochlear stimulation is objectively used in the selection of cochlear implant (CI) candidates to avoid cochlear damage. However, until now, its use is limited due to the large artifacts generated by electrical stimulation. Our objective was to obtain reliable and reproducible electrically evoked auditory brainstem responses (eEABRs) using a new method of stimulation. This was a prospective study including subjects who underwent electrical stimulation on RW during CI surgery between 2013 and 2016. A "Stimulator Box," which produces electric stimuli identical to those provided by a CI, and an evoked potential recording equipment were used. The results obtained with monopolar and bipolar electrodes were compared. RW eEABR recordings of 49 subjects (mean age, 34 years) were characterized by their stability and by having wave V between 3 and 5.5 ms. A higher percentage of responses were obtained on increasing the phase duration instead of the pulse amplitude. A significantly greater percentage of positive responses were obtained using bipolar stimulation than using monopolar stimulation (p<0.001). Using extracochlear electrical stimulation technique, described herein, and bipolar electrical stimulation probe allows for reliable and reproducible eEABR recordings in CI candidates.

Effects of noise and age on the infant brainstem response to speech

ObjectiveBackground noise makes hearing speech difficult for people of all ages. This difficulty can be exacerbated by co-occurring developmental deficits that often emerge in childhood. Sentence-type speech-in-noise (SIN) tests are available clinically but cannot be administered to very young individuals. Our objective was to examine the use of an electrophysiological test of SIN, suitable for infants, to track developmental trajectories. MethodsSpeech-evoked brainstem potentials were recorded from 30 typically-developing infants in quiet and +10 dB SNR background noise. Infants were divided into two age groups (7–12 and 18–24 months) and examined across development. Spectral power of the frequency following response (FFR) was computed using a fast Fourier Transform. Cross-correlations between quiet and noise responses were computed to measure encoding resistance to noise. ResultsOlder infants had more robust FFR encoding in noise and had higher quiet-noise correlations than their younger counterparts. No group differences were observed in the quiet condition. ConclusionsBy two years of age, infants show less vulnerability to the disruptive effects of background noise, compared to infants under 12 months. SignificanceSpeech-in-noise electrophysiology can be easily recorded across infancy and provides unique insights into developmental differences that tests conducted in quiet may miss.

Avaliação audiológica em criança com microcefalia pelo zika vírus: estudo de caso

Introdução: A microcefalia caracteriza-se pela medida do perímetro cefálico de um indivíduo com dois desvios-padrões abaixo da média populacional para sexo e idade. Sabe-se que crianças com microcefalia são consideradas de alto risco para perda auditiva. Portanto, é imprescindível a avaliação e monitoramento audiológico até o terceiro ano de vida. Dentro da bateria de exames, há atualmente novos estímulos, como o Ichirp, que se pode utilizar no Potencial Evocado Auditivo de Tronco Encefálico durante a avaliação. Objetivo: Descrever a avaliação audiológica de uma criança com microcefalia pelo Zika vírus. Método: Foi realizada uma bateria de exames audiológicos: meatoscopia, avaliação comportamental, imitânciometria e o Potencial Evocado Auditivo de Tronco Encefálico, com os estímulos clique e Ichirp. Esses exames foram aplicados em uma criança de sete meses, diagnosticada com microcefalia pelo Zika vírus. Resultados: A criança apresentou exames audiológicos dentro dos padrões de normalidade, com exceção da audiometria de reforço visual. Conclusão: A avaliação audiológica foi dentro dos padrões de normalidade. Deve-se monitorar até o terceiro ano de vida, devido ao risco da perda progressiva. Foram observadas, no PEATE, melhor morfologia e maiores latências das ondas no estímulo Ichirp, quando comparadas ao clique.

The effect of interaural timing on the posterior auricular muscle reflex in normal adult volunteers

The posterior auricular muscle (PAM) reflex to sounds has been used clinically to determine hearing threshold as an alternative to other audiological diagnostic measures such as the auditory brainstem response. We have shown that the PAM response is also sensitive to interaural timing differences in normally hearing adults. PAM responses were evoked by both ipsilateral/ contralateral monaural stimulation and by binaural stimulation. Introducing sound delays ipsilaterally or contralaterally decreased the PAM response amplitude and increased its latency. The PAM response in this study shows a qualitatively similar pattern to that seen by the binaural interaction component (BIC) of the auditory brainstem potential to binaural clicks described in previous studies, in that both: have their shortest latency and maximal amplitudes centred around zero interaural timing differences, have response latencies increase with increasing interaural delays up to 1.2 ms and have response amplitudes decrease with increasing interaural delays of up to 1.2 ms. Our data show that the PAM response may be useful in measuring binaural integration in humans non-invasively for diagnostic or research studies.

S11-4. Deviance-related responses along the auditory hierarchy in the brain

In electrophysiological research, automatic auditory deviance detection has traditionally been associated with mismatch negativity (MMN), a component of the auditory evoked potential (AEP), peaking at 100–250 ms from stimulus onset. However, a series of recent studies have revealed that MMN may no longer represent the earliest electrophysiological response of auditory change detection in human, as shown by deviant modulated middle latency responses (MLRs), peaking at latencies 20–50 ms after stimulus onset. Recently, early correlates of deviance detection can be seen in the frequency following response (FFR), a sustained component of the auditory brainstem potential that is phase-locked to the periodic characteristics of the eliciting stimulus. Here, amplitude modulated sounds were presented to healthy subjects in a frequency oddball paradigm, and deviance-related responses were elicited in the FFR and MLR, as well as the long latency response (LLR), reflected by MMN. These findings demonstrate that different levels along the auditory hierarchy show auditory deviations from a regular sound sequence in one single recording protocol.

Differences in Click and Speech Auditory Brainstem Responses and Cortical Response Patterns: A Pilot Study

Hearing loss has adverse developmental, cognitive and social impacts on individual’s lives. To improve its diagnosis and remediation outcomes, development of objective hearing methods offer new ways of optimizing care strategy. Complementary to the classical click-evoked brainstem and cortical responses, interest grows regarding the speech auditory brainstem responses, whose components, namely the onset and frequency following responses, are proposed as biomarkers of speech encoding at the brainstem level. To improve the understanding of auditory processing in the human brainstem and its effect on cortical processing, we used a multimodal set-up and recorded brainstem and cortical potentials in response to click stimuli and speech stimuli presented at different stimulation intensities in normal hearing adults. We hypothesized that even though click- and onset responses of the speechauditory brainstem responses share some similarities; their underlying mechanisms are in some point distinct. We also presumed that using a noninvasive method we could assess the generators underlying click, onset and frequency following responses and the time wise influence of brainstem encoding on cortical processing of click and speech stimuli. Results showed evidence regarding mechanisms underlying onset response and frequency following response components at the brainstem level. A direct time wise relationship between subcortical encoding and cortical encoding was revealed: cortical activity in the left cortex was related to the onset response latency at the brainstem level. These results highlight the potential use of new methods in speech processing electroencephalographic studies and provide qualitative and topographical data regarding subcortical and cortical auditory processing network.

Audiograms of three subterranean rodent species (genus Fukomys) determined by auditory brainstem responses reveal extremely poor high-frequency hearing.

Life underground has shaped the auditory sense of subterranean mammals, shifting their hearing range to low frequencies. Mole-rats of the genus Fukomys have, however, been suggested to hear at frequencies up to 18.5 kHz, unusually high for a subterranean rodent. We present audiograms of three mole-rat species, Fukomys anselli, Fukomys micklemi and the giant mole-rat Fukomys mechowii, based on evoked auditory brainstem potentials. All species showed low sensitivity and restricted hearing ranges at 60 dB SPL extending from 125 Hz to 4 kHz (5 octaves) with most-sensitive hearing between 0.8 kHz and 1.4 kHz. The high-frequency cut-offs are the lowest found in mammals to date. In contrast to predictions from middle ear morphology, F. mechowii did not show higher sensitivity than F. anselli in the low-frequency range. These data suggest that the hearing range of Fukomys mole-rats is highly restricted to low frequencies and similar to that of other subterranean mammals.

Correction: Audiograms of three subterranean rodent species (genus Fukomys) determined by auditory brainstem responses reveal extremely poor high-frequency cut-offs.

ABSTRACT Life underground has shaped the auditory sense of subterranean mammals, shifting their hearing range to low frequencies. Mole-rats of the genus Fukomys have, however, been suggested to hear at frequencies up to 18.5 kHz, unusually high for a subterranean rodent. We present audiograms of three mole-rat species, Fukomys anselli, Fukomys micklemi and the giant mole-rat Fukomys mechowii, based on evoked auditory brainstem potentials. All species showed low sensitivity and restricted hearing ranges at 60 dB SPL extending from 125 Hz to 4 kHz (5 octaves) with most-sensitive hearing between 0.8 kHz and 1.4 kHz. The high-frequency cut-offs are the lowest found in mammals to date. In contrast to predictions from middle ear morphology, F. mechowii did not show higher sensitivity than F. anselli in the low-frequency range. These data suggest that the hearing range of Fukomys mole-rats is highly restricted to low frequencies and similar to that of other subterranean mammals.

Basilar artery hypoplasia associated with changes of brainstem potential, transcranial Doppler and perfusion-weighted imaging

Objective: The aim of this study was to observe brainstem hemodynamic alterations associated with basilar artery hypoplasia (BAH). Methods: Nine hundred and fifty-two consecutive patients received emergency multimodal computed tomography; magnetic resonance imaging and magnetic resonance angiogram during the period of January 2011 to December 2014 were included. The vascular risk factors, brainstem auditory evoked potential (BAEP), blink reflex (BR), transcranial Doppler (TCD) and dynamic susceptibility contrast-enhanced perfusion-weighted imaging were completed. Results: There was significant difference in the abnormal rates of TCD and BAEP between BAH and non-BAH patients. A positive correlation between basilar artery diameter and systolic velocity among BAH patients was suggested. V-wave value was used to predict posterior circulation infarction (PCI) with the sensitivity of 0.933 and specificity of 0.50 with the cutoff value of 5.97 s. Abnormal BR rate was also significantly different in BAH and non-BAH patients. The latency of R2 was used to predict PCI with the sensitivity of 0.933 and specificity of 0.50 with the cutoff value of 46.4 ms. The incidence of hypoperfusion was higher in BAH than non-BAH group and it was significant difference. Conclusion: BAH is closely associated with hemodynamic alterations within the pons, which might contribute to vascular vertigo due to regional hypoperfusion.

68. Brainstem auditory evoked potentials in children 2–5 years of age with language delays

Introduction Language delay (LD) is a common problem in childhood, the auditory brainstem potentials (ABP) are necessary for early diagnosis. Objetive To describe the abnormalities in auditory brainstem potentials in children 2–5 years with LD. Methodology Transversal study, 50 children, 2–5 years of age, with LD, no history of neurological illness, underwent ABP, evaluating morphology (V/I), absolute latencies of waves I, III and V; interpeak latencies I–III, III–V and I–V, expressed in milliseconds (ms) and hearing threshold expressed in decibels (dB). Results We included 50 patients, 66% boys and 34% girls. In 90% of the ABP there was a reversal V/I ratio. Absolute latencies, conduction intervals and the hearing threshold were normal in all cases. Conclusion The altered morphology of ABP (inversion of the relationship V/I) was related with dysfunction of the inferior colliculus (generator V wave), so it is proposed to complement the evaluation with middle latency responses and logo-audiometry. Significance Early diagnosis and intervention in the management of these children is important to enhance language maturation.

Auditory N1-P2 Cortical Event Related Potentials in Auditory Neuropathy Spectrum Disorder Patients

OBJECTIVE: The purpose of this study was to determine whether a group of patients with auditory neuropathy have abnormal changes in auditory N1-P2 and to analyze the results in those patients and compare them with matched group of normal subjects. MATERIALS and METHODS: Cortical auditory evoked potentials were obtained from nine female and seven male patients with auditory neuropathy, ranging in age from 19 to 48 years. The control group comprised 15 (9 males and 6 females) age-matched, normally hearing adults. Cortical auditory evoked potentials were recorded in both groups. Audiological assessments were performed in both groups, which included pure tone audiometry, speech audiometry, tympanometry, acoustic reflex, distortion products otoacoustic emissions, as well as auditory brainstem potential testing. RESULTS: N1-P2 amplitudes were reduced and latencies were prolonged in the study group, and these parameters were found to be statistically significant when compared to normal subjects (p<0.05). CONCLUSION: The neurophysiologic measures of auditory processing-i.e., N1-P2 response to tonal frequency stimuli-in auditory neuropathy spectrum disorder patients are found to be different. Hence, arguing a doubt on the affection of hypothesize origin of the N1-P2 potential in ANSD

Listening to the brainstem: musicianship enhances intelligibility of subcortical representations for speech.

Auditory experiences including musicianship and bilingualism have been shown to enhance subcortical speech encoding operating below conscious awareness. Yet, the behavioral consequence of such enhanced subcortical auditory processing remains undetermined. Exploiting their remarkable fidelity, we examined the intelligibility of auditory playbacks (i.e., "sonifications") of brainstem potentials recorded in human listeners. We found naive listeners' behavioral classification of sonifications was faster and more categorical when evaluating brain responses recorded in individuals with extensive musical training versus those recorded in nonmusicians. These results reveal stronger behaviorally relevant speech cues in musicians' neural representations and demonstrate causal evidence that superior subcortical processing creates a more comprehensible speech signal (i.e., to naive listeners). We infer that neural sonifications of speech-evoked brainstem responses could be used in the early detection of speech-language impairments due to neurodegenerative disorders, or in objectively measuring individual differences in speech reception solely by listening to individuals' brain activity.