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Background Multiple sclerosis (MS) is an inflammatory demyelinating disease. Auditory evoked potential studies have demonstrated conduction and neural processing deficits in adults with MS, but little is known about the electrophysiological responses in children and adolescents.

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Background/Aim. In everyday communication, people are exposed to a myriad of sounds that need to be sorted and relevant information extracted. The ability of a person to concentrate on certain sounds in a noisy background environment, perform selective attention, and focus their auditory attention is crucial for everyday functioning and communication. The aim of this study was to investigate the effect of the sensorimotor rhythm (SMR) (12–15 Hz) neurofeedback (NFB) training to improve auditory cognition measured by the achievements in the Quick speech-in-noise (QuickSIN) test, changes in the amplitudes and latencies of components of auditory evoked potentials (AEP) N100, N200, and P300 in the auditory oddball discrimination task, and changes in the spectral power of the SMR. Methods. The study included 16 healthy participants aged 25–40 years (8 males and 8 females). Each participant had 20 daily sessions of SMR NFB training. Auditory cognitive functions and electrophysiological correlates of cognitive processing were recorded 5 times – before NFB, after 5, 10, and 20 sessions, and one month after the last session of NFB. Re-sults. The results showed a statistically significant decrease in N200 and P300 latencies at frontal midline (Fz), central midline (Cz), and parietal midline (Pz) regions, an improvement on the QuickSIN test, and an increase in electroencephalogram SMR rhythm spectral power in the Cz region as a result of the NFB SMR training. No significant effect of the NFB training on the N100, N200, and P300 amplitudes on Fz, Cz, and Pz was found. Conclusion. The obtained results suggest that SMR NFB affects auditory perception in terms of shorter latencies of AEP and better performance on the QuickSIN test.

Background/Aim. Neurofeedback (NFB) training of sensorimotor rhythm (SMR) contributes to improving cognitive performance and increasing attention. SMR power is increased when a person is focused and task-oriented. The shorter reaction time (RT) of the P300 auditory evoked potentials (AEPs) is associated with better attention. Hence, the increase in SMR power after NFB SMR training should decrease the RT in a cognitive task. The aim of the study was to examine the ability of healthy individuals to modulate the SMR of electroencephalographic (EEG) activity between 12 and 15 Hz during 20-day NFB training sessions. In addition, the effect of NFB SMR training on RT was investigated. Methods. Participants were divided into experimental and control groups, with 24 subjects (12 males and 12 females) in each group, aged between 25 and 40 years. Participants in the experimental group were trained with authentic NFB SMR training, while in the control group, false (placebo) training was applied. AEPs were registered on five occasions: before NFB training, after 5, 10, and 20 training sessions, and one month after the last training. Results. The results showed that a series of 20 NFB SMR training sessions increased the amplitudes of the SMR. RT in the experimental group was significantly shortened, while in the control group, it was not observed. Moreover, the increase in the power of the EEG signal o f t he S MR showed a negative correlation with RT, but only in a subgroup of male subjects. Conclusion. The obtained results indicate the effects of NFB training on the improvement of the attention process expressed by RT.

ABSTRACT Purpose: to compare the Auditory Middle Latency Response in adults, one group with and another group without altered auditory skills. In addition, the aim was to compare cut-off values of 30% and 50% for the Ear Effect in terms of sensitivity and specificity. Methods: the sample comprised 32 individuals of both genders with no hearing loss who were divided into Group 1 (16 individuals with no alterations in auditory skills) and Group 2 (16 individuals with alterations in auditory skills). All participants received an audiological evaluation and measurement of Brainstem and Auditory Middle Latency Potentials. Results: when Group 1 and Group 2 were compared, a statistically significant difference was only observed in Na and Pa amplitude of waves A1C3 and A2C3. In the analysis of sensitivity and specificity of the Auditory Middle Latency Response, a cut-off value of 50% gave a better balance between sensitivity and specificity. Conclusion: adults presented with altered auditory abilities had smaller response amplitudes in the Na and Pa components of the waves generated in the left hemisphere. A cut-off value of 50% gave a better discrimination of the Ear Effect for identifying subjects with altered auditory skills.

Background/Aim. Neurofeedback (NFB) is a therapeutic method based on monitoring the electroencephalogram (EEG) and providing feedback on the brain activity of sub-jects. The aim of the pilot study was to investigate the effect of lower-beta or sensorimotor rhythm (SMR) (12–15 Hz) NFB training on amplitudes and latencies of late auditory event-related potentials (aERP) components N100, N200, P300 in Go-No go task of auditory discrimination. Methods. Each of 9 healthy participants aged 25–40 years (4 male) had 20 daily sessions of SMR neurofeedback training. The aERP was recorded 5 times: before NFB, after 5, 10, and 20 sessions, and one m onth after the last session. Results. The results showed a statistically significant decrease in N100, N200, and P300 latencies at Fz, Cz, and Pz regions. No significant effect of NFB training on amplitudes of components N100, N200 and N300 was found. Conclusion. The obtained results suggest that NFB training exerts its effect on the processes of auditory cognition.

Congenital or early-onset unilateral hearing loss (UHL) can disrupt the normal development of the auditory system. In extreme cases of UHL (i.e., single sided deafness), consistent cochlear implant use during sensitive periods resulted in cortical reorganization that partially reversed the detrimental effects of unilateral sensory deprivation. There is a gap in knowledge, however, regarding cortical plasticity i.e. the brain's capacity to adapt, reorganize, and develop binaural pathways in milder degrees of UHL rehabilitated by a hearing aid (HA). The current study was set to investigate early-stage cortical processing and electrophysiological manifestations of binaural processing by means of cortical auditory evoked potentials (CAEPs) to speech sounds, in children with moderate to severe-to-profound UHL using a HA. Fourteen children with UHL (CHwUHL), 6-14 years old consistently using a HA for 3.5 (±2.3) years participated in the study. CAEPs were elicited to the speech sounds /m/, /g/, and /t/ in three listening conditions: monaural [Normal hearing (NH), HA], and bilateral [BI (NH + HA)]. Results indicated age-appropriate CAEP morphology in the NH and BI listening conditions in all children. In the HA listening condition: (1) CAEPs showed similar morphology to that found in the NH listening condition, however, the mature morphology observed in older children in the NH listening condition was not evident; (2) P1 was elicited in all but two children with severe-to-profound hearing loss, to at least one speech stimuli, indicating effective audibility; (3) A significant mismatch in timing and synchrony between the NH and HA ear was found; (4) P1 was sensitive to the acoustic features of the eliciting stimulus and to the amplification characteristics of the HA. Finally, a cortical binaural interaction component (BIC) was derived in most children. In conclusion, the current study provides first-time evidence for cortical plasticity and partial reversal of the detrimental effects of moderate to severe-to-profound UHL rehabilitated by a HA. The derivation of a cortical biomarker of binaural processing implies that functional binaural pathways can develop when sufficient auditory input is provided to the affected ear. CAEPs may thus serve as a clinical tool for assessing, monitoring, and managing CHwUHL using a HA., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: The acoustic change complex (ACC) is a cortical auditory evoked potential (CAEP) and can be elicited by a change in an otherwise continuous sound. The ACC has been highlighted as a promising tool in the assessment of sound and speech discrimination capacity, and particularly for difficult-to-test populations such as infants with hearing loss, due to the objective nature of ACC measurements. Indeed, there is a pressing need to develop further means to accurately and thoroughly establish the hearing status of children with hearing loss, to help guide hearing interventions in a timely manner. Despite the potential of the ACC method, ACC measurements remain relatively rare in a standard clinical settings. The objective of this study was to perform an up-to-date systematic review on ACC measurements in children, to provide greater clarity and consensus on the possible methodologies, applications, and performance of this technique, and to facilitate its uptake in relevant clinical settings., Design: Original peer-reviewed articles conducting ACC measurements in children (< 18 years). Data were extracted and summarised for: (1) participant characteristics; (2) ACC methods and auditory stimuli; (3) information related to the performance of the ACC technique; (4) ACC measurement outcomes, advantages, and challenges. The systematic review was conducted using PRISMA guidelines for reporting and the methodological quality of included articles was assessed., Results: A total of 28 studies were identified (9 infant studies). Review results show that ACC responses can be measured in infants (from < 3 months), and there is evidence of age-dependency, including increased robustness of the ACC response with increasing childhood age. Clinical applications include the measurement of the neural capacity for speech and non-speech sound discrimination in children with hearing loss, auditory neuropathy spectrum disorder (ANSD) and central auditory processing disorder (CAPD). Additionally, ACCs can be recorded in children with hearing aids, auditory brainstem implants, and cochlear implants, and ACC results may guide hearing intervention/rehabilitation strategies. The review identified that the time taken to perform ACC measurements was often lengthy; the development of more efficient ACC test procedures for children would be beneficial. Comparisons between objective ACC measurements and behavioural measures of sound discrimination showed significant correlations for some, but not all, included studies., Conclusions: ACC measurements of the neural capacity to discriminate between speech and non-speech sounds are feasible in infants and children, and a wide range of possible clinical applications exist, although more time-efficient procedures would be advantageous for clinical uptake. A consideration of age and maturational effects is recommended, and further research is required to investigate the relationship between objective ACC measures and behavioural measures of sound and speech perception for effective clinical implementation., Competing Interests: Declaration of competing interest None (the authors have no financial disclosures or competing interests to disclose)., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Combining a cochlear implant with contralateral acoustic hearing typically enhances speech understanding, although this improvement varies among CI users and can lead to an interference effect. This variability may be associated with the effectiveness of the integration between electric and acoustic stimulation, which might be affected by the temporal mismatch between the two listening sides. Finding methods to compensate for the temporal mismatch might contribute to the optimal adjustment of bimodal devices and to improve hearing in CI users with contralateral acoustic hearing. The current study investigates cortical auditory evoked potentials (CAEPs) in normal hearing listeners (NH) and CI users with contralateral acoustic hearing. In NH, the amplitude of the N1 peak and the maximum phase locking value (PLV) were analyzed under monaural, binaural, and binaural temporally mismatched conditions. In CI users, CAEPs were measured when listening with CI only (CIS&#95;only), acoustically only (AS&#95;only) and with both sides together (CIS+AS). When listening with CIS+AS, various interaural delays were introduced between the electric and acoustic stimuli. In NH listeners, interaural temporal mismatch resulted in decreased N1 amplitude and PLV. Moreover, PLV is suggested as a more sensitive measure to investigate the integration of information between the two listening sides. CI users showed varied N1 latencies between the AS&#95;only and CIS&#95;only listening conditions, with increased N1 amplitude when the temporal mismatch was compensated. A tendency towards increased PLV was also observed, however, to a lesser extent than in NH listeners, suggesting a limited integration between electric and acoustic stimulation. This work highlights the potential of CAEPs measurement to investigate cortical processing of the information between two listening sides in NH and bimodal CI users., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

The current study investigated the effect of lower frequency input on stream segregation acuity in older, normal hearing adults. Using event-related brain potentials (ERPs) and perceptual performance measures, we previously showed that stream segregation abilities were less proficient in older compared to younger adults. However, in that study we used frequency ranges greater than 1500 Hz. In the current study, we lowered the target frequency range below 1500 Hz and found similar stream segregation abilities in younger and older adults. These results indicate that the perception of complex auditory scenes is influenced by the spectral content of the auditory input and suggest that lower frequency ranges of input in older adults may facilitate listening ability in complex auditory environments. These results also have implications for the advancement of prosthetic devices., Competing Interests: Declaration of competing interest None, (Copyright © 2024. Published by Elsevier B.V.)

Tinnitus denotes the perception of a non-environmental sound and might result from aberrant auditory prediction. Successful prediction of formal (e.g., type) and temporal sound characteristics facilitates the filtering of irrelevant information, also labelled as 'sensory gating' (SG). Here, we explored if and how parallel manipulations of formal prediction violations and temporal predictability affect SG in persons with and without tinnitus. Age-, education- and sex-matched persons with and without tinnitus (N = 52) participated and listened to paired-tone oddball sequences, varying in formal (standard vs. deviant pitch) and temporal predictability (isochronous vs. random timing). EEG was recorded from 128 channels and data were analyzed by means of temporal spatial principal component analysis (tsPCA). SG was assessed by amplitude suppression for the 2nd tone in a pair and was observed in P50-like activity in both timing conditions and groups. Correspondingly, deviants elicited overall larger amplitudes than standards. However, only persons without tinnitus displayed a larger N100-like deviance response in the isochronous compared to the random timing condition. This result might imply that persons with tinnitus do not benefit similarly as persons without tinnitus from temporal predictability in deviance processing. Thus, persons with tinnitus might display less temporal sensitivity in auditory processing than persons without tinnitus., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Following adult-onset hearing impairment, crossmodal plasticity can occur within various sensory cortices, often characterized by increased neural responses to visual stimulation in not only the auditory cortex, but also in the visual and audiovisual cortices. In the present study, we used an established model of loud noise exposure in rats to examine, for the first time, whether the crossmodal plasticity in the audiovisual cortex that occurs following a relatively mild degree of hearing loss emerges solely from altered intracortical processing or if thalamocortical changes also contribute to the crossmodal effects. Using a combination of an established pharmacological 'cortical silencing' protocol and current source density analysis of the laminar activity recorded across the layers of the audiovisual cortex (i.e., the lateral extrastriate visual cortex, V2L), we observed layer-specific changes post-silencing in the strength of the residual visual, but not auditory, input in the noise exposed rats with mild hearing loss compared to rats with normal hearing. Furthermore, based on a comparison of the laminar profiles pre- versus post-silencing in both groups, we can conclude that noise exposure caused a re-allocation of the strength of visual inputs across the layers of the V2L cortex, including enhanced visual-evoked activity in the granular layer; findings consistent with thalamocortical plasticity. Finally, we confirmed that audiovisual integration within the V2L cortex depends on intact processing within intracortical circuits, and that this form of multisensory processing is vulnerable to disruption by noise-induced hearing loss. Ultimately, the present study furthers our understanding of the contribution of intracortical and thalamocortical processing to crossmodal plasticity as well as to audiovisual integration under both normal and mildly-impaired hearing conditions., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2024. Published by Elsevier B.V.)

Background & Rationale: In prior work using non-speech stimuli, children with hearing loss show impaired perception of binaural cues and no significant change in cortical responses to bilateral versus unilateral stimulation. Aims of the present study were to: 1) identify bilateral responses to envelope and spectral components of a speech syllable using the frequency-following response (FFR), 2) determine if abnormalities in the bilateral FFR occur in children with hearing loss, and 3) assess functional consequences of abnormal bilateral FFR responses on perception of binaural timing cues., Methods: A single-syllable speech stimulus (/dα/) was presented to each ear individually and bilaterally. Participants were 9 children with normal hearing (M Age = 12.1 ± 2.5 years) and 6 children with bilateral hearing loss who were experienced bilateral hearing aid users (M Age = 14.0 ± 2.6 years). FFR temporal and spectral peak amplitudes were compared between listening conditions and groups using linear mixed model regression analyses. Behavioral sensitivity to binaural cues were measured by lateralization responses as coming from the right or left side of the head., Results: Both temporal and spectral peaks in FFR responses increased in amplitude in the bilateral compared to unilateral listening conditions in children with normal hearing. These measures of "bilateral advantage" were reduced in the group of children with bilateral hearing loss and associated with decreased sensitivity to interaural timing differences., Conclusion: This study is the first to show that bilateral responses in both temporal and spectral domains can be measured in children using the FFR and is altered in children with hearing loss with consequences to binaural hearing., (Copyright © 2024. Published by Elsevier B.V.)

Purpose: The purpose of this study was to investigate the peripheral and central auditory pathways in adult individuals after COVID-19 infection., Method: A total of 44 individuals aged between 19 and 58 years, of both genders, post-COVID-19 infection, confirmed by serological tests, with no previous hearing complaints and no risk factors for hearing loss, were assessed. All the participants underwent the following procedures: pure tone audiometry, logoaudiometry, immitanciometry, and Brainstem Auditory Evoked Potentials (BAEP), in addition to answering a questionnaire about auditory symptoms., Results: Thirteen individuals (29.5 %) had some hearing threshold impairment, mainly sensorineural hearing loss. In the BAEP, 18 individuals (40.9 %) presented longer latencies, mainly in waves III and V. According to the questionnaire answers, 3 individuals (9.1 %) reported worsened hearing and 7 (15.9 %) tinnitus that emerged after the infection. As for the use of ototoxic drugs during treatment, 7 individuals (15.9 %) reported their use, of which 5 showed abnormalities in peripheral and/or central auditory assessments., Conclusion: Considering the self-reported hearing complaints after COVID-19 infection and the high rate of abnormalities found in both peripheral and central audiological assessments, it is suggested that the new COVID-19 may compromise the auditory system. Due to the many variables involved in this study, the results should be considered with caution. However, it is essential that audiological evaluations are carried out on post-COVID-19 patients in order to assess the effects of the infection in the short, medium, and long term. Future longitudinal investigations are important for a better understanding of the auditory consequences of COVID-19., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024. Published by Elsevier España, S.L.U.)

Tinnitus, the perception of sound with no external auditory stimulus, is a complex, multifaceted, and potentially devastating disorder. Despite recent advances in our understanding of tinnitus, there are limited options for effective treatment. Tinnitus treatments are made more complicated by the lack of a test for tinnitus based on objectively measured physiological characteristics. Such an objective test would enable a greater understanding of tinnitus mechanisms and may lead to faster treatment development in both animal and human research. This review makes the argument that an objective tinnitus test, such as a non-invasive electrophysiological measure, is desperately needed. We review the current tinnitus assessment methods, the underlying neural correlates of tinnitus, the multiple tinnitus generation theories, and the previously investigated electrophysiological measurements of tinnitus. Finally, we propose an alternate objective test for tinnitus that may be valid in both animal and human subjects., Competing Interests: Declaration of competing interest The authors have a patent pending for the development of a ‘long-duration sound test’ that could be used as a tool to test for tinnitus., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Neurons within a neuronal network can be grouped by bottom-up and top-down influences using synchrony in neuronal oscillations. This creates the representation of perceptual objects from sensory features. Oscillatory activity can be differentiated into stimulus-phase-locked (evoked) and non-phase-locked (induced). The former is mainly determined by sensory input, the latter by higher-level (cortical) processing. Effects of auditory deprivation on cortical oscillations have been studied in congenitally deaf cats (CDCs) using cochlear implant (CI) stimulation. CI-induced alpha, beta, and gamma activity were compromised in the auditory cortex of CDCs. Furthermore, top-down information flow between secondary and primary auditory areas in hearing cats, conveyed by induced alpha oscillations, was lost in CDCs. Here we used the matching pursuit algorithm to assess components of such oscillatory activity in local field potentials recorded in primary field A1. Additionally to the loss of induced alpha oscillations, we also found a loss of evoked theta activity in CDCs. The loss of theta and alpha activity in CDCs can be directly related to reduced high-frequency (gamma-band) activity due to cross-frequency coupling. Here we quantified such cross-frequency coupling in adult 1) hearing-experienced, acoustically stimulated cats (aHCs), 2) hearing-experienced cats following acute pharmacological deafening and subsequent CIs, thus in electrically stimulated cats (eHCs), and 3) electrically stimulated CDCs. We found significant cross-frequency coupling in all animal groups in > 70% of auditory-responsive sites. The predominant coupling in aHCs and eHCs was between theta/alpha phase and gamma power. In CDCs such coupling was lost and replaced by alpha oscillations coupling to delta/theta phase. Thus, alpha/theta oscillations synchronize high-frequency gamma activity only in hearing-experienced cats. The absence of induced alpha and theta oscillations contributes to the loss of induced gamma power in CDCs, thereby signifying impaired local network activity., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Older listeners have difficulty processing temporal cues that are important for word discrimination, and deficient processing may limit their ability to benefit from these cues. Here, we investigated aging effects on perception and neural representation of the consonant transition and the factors that contribute to successful perception. To further understand the neural mechanisms underlying the changes in processing from brainstem to cortex, we also examined the factors that contribute to exaggerated amplitudes in cortex. We enrolled 30 younger normal-hearing and 30 older normal-hearing participants who met the criteria of clinically normal hearing. Perceptual identification functions were obtained for the words BEAT and WHEAT on a 7-step continuum of consonant-transition duration. Auditory brainstem responses (ABRs) were recorded to click stimuli and frequency-following responses (FFRs) and cortical auditory-evoked potentials were recorded to the endpoints of the BEAT-WHEAT continuum. Perceptual performance for identification of BEAT vs. WHEAT did not differ between younger and older listeners. However, both subcortical and cortical measures of neural representation showed age group differences, such that FFR phase locking was lower but cortical amplitudes (P1 and N1) were higher in older compared to younger listeners. ABR Wave I amplitude and FFR phase locking, but not audiometric thresholds, predicted early cortical amplitudes. Phase locking to the transition region and early cortical peak amplitudes (P1) predicted performance on the perceptual identification function. Overall, results suggest that the neural representation of transition durations and cortical overcompensation may contribute to the ability to perceive transition duration contrasts. Cortical overcompensation appears to be a maladaptive response to decreased neural firing/synchrony., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Introduction: Central auditory processing refers to the efficiency and effectiveness with which the central nervous system uses auditory information: it may be altered in neurological disorders and brain injuries, such as strokes. However, despite evidence of probable alterations in the pediatric population, functional abilities and post-stroke limitations are still not well documented in the literature. Objective: To analyze the findings of the electrophysiological and behavioral evaluations of central auditory processing of children and adolescents diagnosed with stroke from a reference outpatient clinic, as well as to investigate possible associations with the variables: type and location of the stroke and age group. Methods: The present study is characterized as comparative cross-sectional. The sample, for convenience, included individuals aged 7–18 years divided into two groups: study group, composed of individuals with a diagnosis of stroke, and control group, composed of individuals with typical development. The evaluation consisted of the following procedures: anamnesis, basic audiological evaluation, behavioral evaluation of the auditory processing disorder (dichotic digit test, dichotic consonant-vowel, synthetic sentence identification/pediatric speech intelligibility, gaps in noise, pitch pattern sequence, masking level difference), and electrophysiological evaluation (P300 and mismatch negativity). Results: Nineteen children and adolescents were included in the study group. The control group was composed of 19 children and adolescents with typical development. In the comparison between the groups, a worse performance is observed for the study group in all the evaluated tests, behavioral and electrophysiological. In the behavioral evaluation of central auditory processing, there was a statistical difference for all tests, except for masking level difference and dichotic digit test, binaural separation step on the left. In the electrophysiological evaluation, there was a statistical difference in the latency of mismatch negativity and P300. No associations were found between the behavioral and electrophysiological findings and the location of the stroke and age group variables. Conclusion: Children and adolescents diagnosed with stroke present a worse performance in the electrophysiological and behavioral evaluations of central auditory processing when compared to a control group.

ABSTRACT Objective To analyze age-related changes in the central auditory pathway in healthy elderly individuals. Methods A prospective, quantitative cross-sectional study. The caseload comprised 18 adults (mean age, 22.78 years) and 18 elderly individuals (mean age, 66.72 years) of both sexes, who met inclusion criteria. Subjects were submitted to basic audiological evaluation and related electrophysiologic tests: brainstem auditory evoked potential with click stimulus and frequency-following response. Results Elderly individuals had higher wave and interpeak latencies (waves I, III and V and interpeaks I-V and III-V) of brainstem auditory evoked potential. Latencies of frequency following response waves A, E, F and O were also higher in elderly individuals. Frequency following response amplitudes were better in A than in D, F and O waves in these subjects. Likewise, interpeak intervals (V-A and V-O) were larger in elderly relative to adult individuals. Lower slope values were observed in elderly individuals. Conclusion Brainstem auditory evoked potential and frequency-following response allowed appropriate assessment of age-related changes in the auditory pathway. Slower neural response to auditory stimuli suggests reduced synchrony between neural structures.

Aberrant neuronal circuit dynamics are at the core of complex neuropsychiatric disorders, such as schizophrenia (SZ). Clinical assessment of the integrity of neuronal circuits in SZ has consistently described aberrant resting-state gamma oscillatory activity, decreased auditory-evoked gamma responses, and abnormal mismatch responses. We hypothesized that corticothalamic circuit manipulation could recapitulate SZ circuit phenotypes in rodent models. In this study, we optogenetically inhibited the mediodorsal thalamus-to-prefrontal cortex (MDT-to-PFC) or the PFC-to-MDT projection in rats and assessed circuit function through electrophysiological readouts. We found that MDT-PFC perturbation could not recapitulate SZ-linked phenotypes such as broadband gamma disruption, altered evoked oscillatory activity, and diminished mismatch negativity responses. Therefore, the induced functional impairment of the MDT-PFC pathways cannot account for the oscillatory abnormalities described in SZ., (© 2024. The Author(s).)

Despite that fact that the cochlear implant (CI) is one of the most successful neuro-prosthetic devices which allows hearing restoration, several aspects still need to be improved. Interactions between stimulating electrodes through current spread occurring within the cochlea drastically limit the number of discriminable frequency channels and thus can ultimately result in poor speech perception. One potential solution relies on the use of new pulse shapes, such as asymmetric pulses, which can potentially reduce the current spread within the cochlea. The present study characterized the impact of changing electrical pulse shapes from the standard biphasic symmetric to the asymmetrical shape by quantifying the evoked firing rate and the spatial activation in the guinea pig primary auditory cortex (A1). At a fixed charge, the firing rate and the spatial activation in A1 decreased by 15 to 25 % when asymmetric pulses were used to activate the auditory nerve fibers, suggesting a potential reduction of the spread of excitation inside the cochlea. A strong "polarity-order" effect was found as the reduction was more pronounced when the first phase of the pulse was cathodic with high amplitude. These results suggest that the use of asymmetrical pulse shapes in clinical settings can potentially reduce the channel interactions in CI users., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Auditory nerve (AN) function has been hypothesized to deteriorate with age and noise exposure. Here, we perform a systematic review of published studies and find that the evidence for age-related deficits in AN function is largely consistent across the literature, but there are inconsistent findings among studies of noise exposure history. Further, evidence from animal studies suggests that the greatest deficits in AN response amplitudes are found in noise-exposed aged mice, but a test of the interaction between effects of age and noise exposure on AN function has not been conducted in humans. We report a study of our own examining differences in the response amplitude of the compound action potential N1 (CAP N1) between younger and older adults with and without a self-reported history of noise exposure in a large sample of human participants (63 younger adults 18-30 years of age, 103 older adults 50-86 years of age). CAP N1 response amplitudes were smaller in older than younger adults. Noise exposure history did not appear to predict CAP N1 response amplitudes, nor did the effect of noise exposure history interact with age. We then incorporated our results into two meta-analyses of published studies of age and noise exposure history effects on AN response amplitudes in neurotypical human samples. The meta-analyses found that age effects across studies are robust (r = -0.407), but noise exposure effects are weak (r = -0.152). We conclude that noise exposure effects may be highly variable depending on sample characteristics, study design, and statistical approach, and researchers should be cautious when interpreting results. The underlying pathology of age-related and noise-induced changes in AN function are difficult to determine in living humans, creating a need for longitudinal studies of changes in AN function across the lifespan and histological examination of the AN from temporal bones collected post-mortem., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Limited auditory input, whether caused by hearing loss or by electrical stimulation through a cochlear implant (CI), can be compensated by the remaining senses. Specifically for CI users, previous studies reported not only improved visual skills, but also altered cortical processing of unisensory visual and auditory stimuli. However, in multisensory scenarios, it is still unclear how auditory deprivation (before implantation) and electrical hearing experience (after implantation) affect cortical audiovisual speech processing. Here, we present a prospective longitudinal electroencephalography (EEG) study which systematically examined the deprivation- and CI-induced alterations of cortical processing of audiovisual words by comparing event-related potentials (ERPs) in postlingually deafened CI users before and after implantation (five weeks and six months of CI use). A group of matched normal-hearing (NH) listeners served as controls. The participants performed a word-identification task with congruent and incongruent audiovisual words, focusing their attention on either the visual (lip movement) or the auditory speech signal. This allowed us to study the (top-down) attention effect on the (bottom-up) sensory cortical processing of audiovisual speech. When compared to the NH listeners, the CI candidates (before implantation) and the CI users (after implantation) exhibited enhanced lipreading abilities and an altered cortical response at the N1 latency range (90-150 ms) that was characterized by a decreased theta oscillation power (4-8 Hz) and a smaller amplitude in the auditory cortex. After implantation, however, the auditory-cortex response gradually increased and developed a stronger intra-modal connectivity. Nevertheless, task efficiency and activation in the visual cortex was significantly modulated in both groups by focusing attention on the visual as compared to the auditory speech signal, with the NH listeners additionally showing an attention-dependent decrease in beta oscillation power (13-30 Hz). In sum, these results suggest remarkable deprivation effects on audiovisual speech processing in the auditory cortex, which partially reverse after implantation. Although even experienced CI users still show distinct audiovisual speech processing compared to NH listeners, pronounced effects of (top-down) direction of attention on (bottom-up) audiovisual processing can be observed in both groups. However, NH listeners but not CI users appear to show enhanced allocation of cognitive resources in visually as compared to auditory attended audiovisual speech conditions, which supports our behavioural observations of poorer lipreading abilities and reduced visual influence on audition in NH listeners as compared to CI users., (Copyright © 2024. Published by Elsevier B.V.)

Our brain is constantly extracting, predicting, and recognising key spatiotemporal features of the physical world in order to survive. While neural processing of visuospatial patterns has been extensively studied, the hierarchical brain mechanisms underlying conscious recognition of auditory sequences and the associated prediction errors remain elusive. Using magnetoencephalography (MEG), we describe the brain functioning of 83 participants during recognition of previously memorised musical sequences and systematic variations. The results show feedforward connections originating from auditory cortices, and extending to the hippocampus, anterior cingulate gyrus, and medial cingulate gyrus. Simultaneously, we observe backward connections operating in the opposite direction. Throughout the sequences, the hippocampus and cingulate gyrus maintain the same hierarchical level, except for the final tone, where the cingulate gyrus assumes the top position within the hierarchy. The evoked responses of memorised sequences and variations engage the same hierarchical brain network but systematically differ in terms of temporal dynamics, strength, and polarity. Furthermore, induced-response analysis shows that alpha and beta power is stronger for the variations, while gamma power is enhanced for the memorised sequences. This study expands on the predictive coding theory by providing quantitative evidence of hierarchical brain mechanisms during conscious memory and predictive processing of auditory sequences., (© 2024. The Author(s).)

Background: Encephalopathy of different etiologies in infants is often the reason for central respiratory insufficiency which eventually leads patients to the Pediatric Intensive Care Unit. Magnetic resonance imaging (MRI) and brainstem auditory evoked potentials (BAEPs) may be useful to identify brainstem alterations among patients with respiratory insufficiency of central origin. MRI is a compulsory technique to identify brain abnormalities, but may fail to detect brainstem lesions of small dimensions. BAEPs play a highly sensitive role on brainstem dysfunction identification because of the generators of different peaks which are related to specific brainstem structures., Methods: The study included ten infants affected by encephalopathy of different etiologies and early neurological respiratory failure. To evaluate BAEPs, the surface electrodes were placed at the vertex (Cz) and on each mastoid side., Results: All subjects presented alteration of BAEPs. The brain MRI revealed selective injury of the brainstem in four patients and supratentorial alterations in six patients., Conclusions: The early identification of brainstem lesions in mechanically ventilated infants with encephalopathy may reduce the weaning off mechanical ventilation's attempt numbers and provide early informative discussions with families and clinical caregivers about treatment options, such as tracheostomy, long term ventilation and the reduction of their length of PICU stay. Furthermore, this would support the evaluation process concerning the affected children, their families and the needs of other social groups, including health systems.

Objective: Increasing perceptual load alters behavioral outcomes in post-stroke fatigue (PSF). While the effect of perceptual load on top-down attentional processing is known, here we investigate if increasing perceptual load modulates bottom-up attentional processing in a fatigue dependent manner., Methods: In this cross-sectional observational study, in 29 first-time stroke survivors with no clinical depression, an auditory oddball task consisting of target, standard, and novel tones was performed in conditions of low and high perceptual load. Electroencephalography was used to measure auditory evoked potentials. Perceived effort was rated using the visual analog scale at regular intervals during the experiment. Fatigue was measured using the fatigue severity scale. The effect of fatigue and perceptual load on behavior (response time, accuracy, and effort rating) and auditory evoked potentials (amplitude and latency) was examined using mixed model ananlysis of variances (ANOVA)., Results: Response time was prolonged with greater perceptual load and fatigue. There was no effect of load or fatigue on accuracy. Greater effort was reported with higher perceptual load both in high and low fatigue. p300a amplitude of auditory evoked potentials (AEP) for novel stimuli was attenuated in high fatigue with increasing load when compared to low fatigue. Latency of p300a was longer in low fatigue with increasing load when compared to high fatigue. There were no effects on p300b components, with smaller N100 in high load conditions., Interpretation: High fatigue specific modulation of p300a component of AEP with increasing load is indicative of distractor driven alteration in orienting response, suggestive of compromise in bottom-up selective attention in PSF., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Advancements in portable neuroimaging technologies open up new opportunities to gain insight into the neural dynamics and cognitive processes underlying day-to-day behaviors. In this study, we evaluated the relevance of a headphone- mounted electroencephalogram (EEG) system for monitoring mental workload. The participants (N = 12) were instructed to pay attention to auditory alarms presented sporadically while performing the Multi-Attribute Task Battery (MATB) whose difficulty was staged across three conditions to manipulate mental workload. The P300 Event-Related Potentials (ERP) elicited by the presentation of auditory alarms were used as probes of attentional resources available. The amplitude and latency of P300 ERPs were compared across experimental conditions. Our findings indicate that the P300 ERP component can be captured using a headphone-mounted EEG system. Moreover, neural responses to alarm could be used to classify mental workload with high accuracy (over 80%) at a single-trial level. Our analyses indicated that the signal-to-noise ratio acquired by the sponge-based sensors remained stable throughout the recordings. These results highlight the potential of portable neuroimaging technology for the development of neuroassistive applications while underscoring the current limitations and challenges associated with the integration of EEG sensors in everyday-life wearable technologies. Overall, our study contributes to the growing body of research exploring the feasibility and validity of wearable neuroimaging technologies for the study of human cognition and behavior in real-world settings., (Copyright © 2023 Elsevier B.V. All rights reserved.)

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., (© 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).)

Objective: Exploring the electrophysiological changes of auditory rehabilitation in young children with hearing impairment, providing more methods for early assessment and intervention. Methods: Twenty children aged 2-4 were enrolled, with moderate hearing loss and no other abnormalities in the ears. Divide them into group 1 with normal hearing, group 2 with abnormal hearing, group 3 with abnormal hearing receiving hearing aid intervention for one year, and group 4 with abnormal hearing receiving hearing aid and language training rehabilitation for one year. The SmartEP auditory evoked potential instrument was used to detect speech induced ABR and conduct screening for 'Standards and Evaluating Hearing and Language Abilities of Children with Hearing Impairment in 80 enrolled children after rehabilitation training, and the latency、amplitude of speech induced ABR waveform and evaluation scale scores for each group after rehabilitation intervention were compared. Results: Compared with the normal group, the latency of each wave in the other three groups was prolonged. The differences in each wave between Group 2 and Group 3 were statistically significant, while the differences in D and F waves between Group 3 and Group 4 were statistically significant. Compared with the normal group, the maximum amplitude at F0 decreased in the other three groups, and the differences in maximum amplitude between Group 2 and Group 3, Group 2 and Group 4, and Group 3 and Group 4 were statistically significant. Compared with the normal group, the scores of the auditory language assessment scale in the hearing intervention group and the hearing aid plus language training group were significantly higher than those in the abnormal group in terms of recognition rate. The recognition rates of hearing impaired children with language training foundation are similar to those of the normal group of children. Conclusion: Auditory rehabilitation can alter the electrophysiological aspects of hearing and serve as a basis for early assessment and intervention in young children., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.)

Purpose: Amplitude modulations (AMs) are important for speech intelligibility, and deficits in speech intelligibility are a leading source of impairment in childhood listening difficulties (LiD). The present study aimed to explore the relationships between AM perception and speech-in-noise (SiN) comprehension in children and to determine whether deficits in AM processing contribute to childhood LiD. Evoked responses were used to parse the neural origins of AM processing., Method: Forty-one children with LiD and 44 typically developing children, ages 8-16 years, participated in the study. Behavioral AM depth thresholds were measured at 4 and 40 Hz. SiN tasks included the Listening in Spatialized Noise-Sentences Test (LiSN-S) and a coordinate response measure (CRM)-based task. Evoked responses were obtained during an AM change detection task using alternations between 4 and 40 Hz, including the N1 of the acoustic change complex, auditory steady-state response (ASSR), P300, and a late positive response (late potential [LP]). Maturational effects were explored via age correlations., Results: Age correlated with 4-Hz AM thresholds, CRM separated talker scores, and N1 amplitude. Age-normed LiSN-S scores obtained without spatial or talker cues correlated with age-corrected 4-Hz AM thresholds and area under the LP curve. CRM separated talker scores correlated with AM thresholds and area under the LP curve. Most behavioral measures of AM perception correlated with the signal-to-noise ratio and phase coherence of the 40-Hz ASSR. AM change response time also correlated with area under the LP curve. Children with LiD exhibited deficits with respect to 4-Hz thresholds, AM change accuracy, and area under the LP curve., Conclusions: The observed relationships between AM perception and SiN performance extend the evidence that modulation perception is important for understanding SiN in childhood. In line with this finding, children with LiD demonstrated poorer performance on some measures of AM perception, but their evoked responses implicated a primarily cognitive deficit., Supplemental Material: https://doi.org/10.23641/asha.25009103.

Eye movements have been extensively studied with respect to visual stimulation. However, we live in a multisensory world, and how the eyes are driven by other senses has been explored much less. Here, we review the evidence on how audition can trigger and drive different eye responses and which cortical and subcortical neural correlates are involved. We provide an overview on how different types of sounds, from simple tones and noise bursts to spatially localized sounds and complex linguistic stimuli, influence saccades, microsaccades, smooth pursuit, pupil dilation, and eye blinks. The reviewed evidence reveals how the auditory system interacts with the oculomotor system, both behaviorally and neurally, and how this differs from visually driven eye responses. Some evidence points to multisensory interaction, and potential multisensory integration, but the underlying computational and neural mechanisms are still unclear. While there are marked differences in how the eyes respond to auditory compared to visual stimuli, many aspects of auditory-evoked eye responses remain underexplored, and we summarize the key open questions for future research., (© 2023 The New York Academy of Sciences.)

Background: We interrogated auditory sensory memory capabilities in individuals with CLN3 disease (juvenile neuronal ceroid lipofuscinosis), specifically for the feature of "duration" processing. Given decrements in auditory processing abilities associated with later-stage CLN3 disease, we hypothesized that the duration-evoked mismatch negativity (MMN) of the event related potential (ERP) would be a marker of progressively atypical cortical processing in this population, with potential applicability as a brain-based biomarker in clinical trials., Methods: We employed three stimulation rates (fast: 450 ms, medium: 900 ms, slow: 1800 ms), allowing for assessment of the sustainability of the auditory sensory memory trace. The robustness of MMN directly relates to the rate at which the regularly occurring stimulus stream is presented. As presentation rate slows, robustness of the sensory memory trace diminishes. By manipulating presentation rate, the strength of the sensory memory trace is parametrically varied, providing greater sensitivity to detect auditory cortical dysfunction. A secondary hypothesis was that duration-evoked MMN abnormalities in CLN3 disease would be more severe at slower presentation rates, resulting from greater demand on the sensory memory system., Results: Data from individuals with CLN3 disease (N = 21; range 6-28 years of age) showed robust MMN responses (i.e., intact auditory sensory memory processes) at the medium stimulation rate. However, at the fastest rate, MMN was significantly reduced, and at the slowest rate, MMN was not detectable in CLN3 disease relative to neurotypical controls (N = 41; ages 6-26 years)., Conclusions: Results reveal emerging insufficiencies in this critical auditory perceptual system in individuals with CLN3 disease., (© 2023. The Author(s).)

Auditory complaints are frequently reported by individuals with mild traumatic brain injury (mTBI) yet remain difficult to detect in the absence of clinically significant hearing loss. This highlights a growing need to identify sensitive indices of auditory-related mTBI pathophysiology beyond pure-tone thresholds for improved hearing healthcare diagnosis and treatment. Given the heterogeneity of mTBI etiology and the diverse peripheral and central processes required for normal auditory function, the present study sought to determine the audiologic assessments sensitive to mTBI pathophysiology at the group level using a well-rounded test battery of both peripheral and central auditory system function. This test battery included pure-tone detection thresholds, word understanding in quiet, sentence understanding in noise, distortion product otoacoustic emissions (DPOAEs), middle-ear muscle reflexes (MEMRs), and auditory evoked potentials (AEPs), including auditory brainstem responses (ABRs), middle latency responses (MLRs), and late latency responses (LLRs). Each participant also received magnetic resonance imaging (MRI). Compared to the control group, we found that individuals with mTBI had reduced DPOAE amplitudes that revealed a compound effect of age, elevated MEMR thresholds for an ipsilateral broadband noise elicitor, longer ABR Wave I latencies for click and 4 kHz tone burst elicitors, longer ABR Wave III latencies for 4 kHz tone bursts, larger MLR Na and Nb amplitudes, smaller MLR Pb amplitudes, longer MLR Pa latencies, and smaller LLR N1 amplitudes for older individuals with mTBI. Further, mTBI individuals with combined hearing difficulty and noise sensitivity had a greater number of deficits on thalamic and cortical AEP measures compared to those with only one/no self-reported auditory symptoms. This finding was corroborated with MRI, which revealed significant structural differences in the auditory cortical areas of mTBI participants who reported combined hearing difficulty and noise sensitivity, including an enlargement of left transverse temporal gyrus (TTG) and bilateral planum polare (PP). These findings highlight the need for continued investigations toward identifying individualized audiologic assessments and treatments that are sensitive to mTBI pathophysiology., Competing Interests: Declaration of Competing Interest René H. Gifford is a consultant for Advanced Bionics, Cochlear Limited, Akouos, and Frequency Therapeutics. Linda J. Hood is a consultant for Akouos and Pfizer. These consultant roles are not in conflict with the work reported here and there are no other conflicts of interest, financial or otherwise, to disclose., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Objectives: To investigate the effects of hypoxia occurring in patients with Obstructive Sleep Apnea Syndrome (OSAS) on Auditory evoked late latency, Auditory brainstem response, and the contralateral suppression of otoacoustic emissions., Materials and Methods: 46 patients diagnosed with OSAS were divided into groups as moderate and severe based on their Apnea Hipopnea Index (AHI) values. The control group consisted of 22 healthy individuals. All participants underwent an Auditory Brainstem Response (ABR) test, Auditory Evoked Late Latency Response (LLR), and Contralateral Suppression Otoacoustic Emission (CS-OAE)., Findings: There was no statistical difference between the OSAS group and the control group regarding P1 latency, N1 latency, and P1 and N1 wave amplitude (p > 0.05). In ABR, statistically significant differences were found between the control, moderate OSAS, and severe OSAS groups in wave I in the right and left ear (p < 0.05). In the analyses performed for the otoacoustic emission frequencies with and without contralateral suppression of the right and left ear, suppression was not observed at some frequencies, and this was regarded as statistically significant (p < 0.05)., Conclusion: It is considered that OSAS does not have cortical effects but impacts the brainstem region and the cochlea. Bilateral impact, especially observed in wave I of ABR, is prominent on the auditory nerve. Considering that the medial olivo-cochlear (MOC) system is affected in patients with OSAS, it is thought that these patients are inadequate in suppressing noise, and this may cause various problems, particularly the inability to distinguish speech in noisy environments., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Omitted stimulus potentials (OSPs) occur when a sensory stimulus is unexpectedly omitted. They are thought to reflect predictions about upcoming sensory events. The present study examined how OSPs differ across the sensory modalities of predicted stimuli. Twenty-nine university students were asked to press a mouse button at a regular interval of 1-2 s, which was immediately followed by either a visual or auditory stimulus in different blocks. The stimuli were sometimes omitted (p = 0.2), to which event-related potentials (ERPs) were recorded. The results showed that stimulus omissions in both modalities elicited ERP waveforms consisting of three components, oN1, oN2, and oP3. The peak latencies of these components were shorter in the auditory modality than in the visual modality. The amplitudes of OSPs were larger when participants were told that the omission indicated their poor performance (i.e., they pressed a button at an irregular interval) than when it was irrelevant to their performance. These findings suggest that OSPs occur from around 100 ms in a modality-specific manner and increase in amplitude depending on the task relevance of stimulus omissions., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)