Auditory Changes Research Articles

Auditory agnosia progressing to cortical deafness. Long-term follow up of a one-year-old child to age 37

Background There are two types of central auditory disorders due to pathology of the bilateral auditory cortices in adult patients: auditory agnosia with residual hearing; cortical deafness with total hearing loss. However, long-term changes of hearing acuity over physical development time are unknown. Objective The aim of this case report was to illustrate the pathophysiology of auditory changes in a 1 year-3 months old child who was diagnosed with auditory agnosia as a sequel of herpes encephalitis and later developed cortical deafness during a 36-year follow-up. Materials and Methods Brain MRI, hearing tests, ABR, DPOAE and developmental tests of speech/language were periodically performed. Results Brain imaging revealed extensive damage in the bilateral auditory cortices. His auditory speech perception was lost and his language development was seriously delayed. His hearing threshold progressively decreased over time from normal at first to profound hearing loss as a teenager. However, at 29 years of age his ABR was normal. He was able to communicate and converse by sign language or writing. Conclusions and Significance Later developing cortical deafness with profound hearing loss could be caused by retrograde degeneration of the auditory radiation overtime to the bilateral medial geniculate bodies.

Auditory changes in awake guinea pigs exposed to overcompressed music

Exposure to loud sound during leisure time is identified as a significant risk factor for hearing by health authorities worldwide. The current standard that defines unsafe exposure rests on the equal-energy hypothesis, according to which the maximum recommended exposure is a tradeoff between level and daily exposure duration, a satisfactory recipe except for strongly non-Gaussian intense sounds such as gunshots. Nowadays, sound broadcast by music and videoconference streaming services makes extensive use of numerical dynamic range compression. By filling in millisecond-long valleys in the signal to prevent competing noise from masking, it pulls sound-level statistics away from a Gaussian distribution, the framework where the equal-energy hypothesis emerged.Auditory effects of a single 4 hour exposure to the same music were compared in two samples of guinea pigs exposed either to its original or overcompressed version played at the same average level of 102 dBA allowed by French regulations. Apart from a temporary shift of otoacoustic emissions at the lowest two frequencies 2 and 3 kHz, music exposure had no detectable cochlear effect, as monitored at 1, 2 and 7 days post-exposure. Conversely, middle-ear muscle strength behaved differentially as the group exposed to original music had fully recovered one day after exposure whereas the group exposed to overcompressed music remained stuck to about 50% of baseline even after 7 days. Subsamples were then re-exposed to the same music as the first time and sacrificed for density measurements of inner-hair-cell synapses. No difference in synaptic density was found compared to unexposed controls with either type of music.The present results show that the same music piece, harmless when played in its original version, induces a protracted deficit of one auditory neural pathway when overcompressed at the same level. The induced disorder does not seem to involve inner-hair cell synapses.

An observational study of auditory-evoked potential mismatch negativity response in individuals at high genetic risk for schizophrenia

Objectives: This study presents a novel approach by investigating the abnormal mismatch negativity (MMN) found during response to auditory-evoked potential (ERP) in schizophrenia (SZ) patients. Our unique focus is on the genetic high-risk (GHR) for SZ, comparing it with healthy controls (HC). In addition, we aim to illuminate the interrelationship of MMN with socio-occupational functioning in the GHR group, a novel aspect of our research. Material and Methods: We conducted this study with a rigorous methodology, ensuring the reliability and validity of our findings. Thirty first-degree relatives of SZ patients (GHR) who met the inclusion and exclusion criteria were recruited by purposive sampling and compared with thirty HCs. We collected sociodemographic and clinical data from all study participants, which were assessed by the Family Interview of Genetic Studies. GHR was evaluated for current socio-occupation functioning using the Social and Occupational Functioning Assessment Scale (SOFAS). All the participants underwent 128-channel electroencephalographic recording using an auditory-evoked responses paradigm. The MMN was calculated at the frontal electrode clusters, ensuring accurate and reliable data collection. Results: The study revealed a statistically significant difference in frontal MMN latency between GHR and HC. Moreover, a positive relationship was noted between the SOFAS score and MMN amplitude, and a negative relationship was found between the latencies at the frontal region. Conclusion: Our research has made a significant breakthrough in understanding SZ. Our findings reveal that individuals with a genetic susceptibility to SZ exhibit a unique response in a particular test known as MMN. This test measures the automatic auditory change detection mechanism, which detects minor alterations in the acoustic environment and is referred to as MMN. This newfound insight could prove instrumental in developing more effective diagnoses and treatments for SZ.

Lower Childhood Socioeconomic Status Is Associated with Greater Neural Responses to Ambient Auditory Changes in Adulthood.

Humans' early life experience varies by socioeconomic status (SES), raising the question of how this difference is reflected in the adult brain. An important aspect of brain function is the ability to detect salient ambient changes while focusing on a task. Here, we ask whether subjective social status during childhood is reflected by the way young adults' brain detecting changes in irrelevant information. In two studies (total n = 58), we examine electrical brain responses in the frontocentral region to a series of auditory tones, consisting of standard stimuli (80%) and deviant stimuli (20%) interspersed randomly, while participants were engaged in various visual tasks. Both studies showed stronger automatic change detection indexed by MMN in lower SES individuals, regardless of the unattended sound's feature, attended emotional content, or study type. Moreover, we observed a larger MMN in lower-SES participants, although they did not show differences in brain and behavior responses to the attended task. Lower-SES people also did not involuntarily orient more attention to sound changes (i.e., deviant stimuli), as indexed by the P3a. The study indicates that individuals with lower subjective social status may have an increased ability to automatically detect changes in their environment, which may suggest their adaptation to their childhood environments.

Auditory change detection and visual selective attention: association between MMN and N2pc.

While the auditory and visual systems each provide distinct information to our brain, they also work together to process and prioritize input to address ever-changing conditions. Previous studies highlighted the trade-off between auditory change detection and visual selective attention; however, the relationship between them is still unclear. Here, we recorded electroencephalography signals from 106 healthy adults in three experiments. Our findings revealed a positive correlation at the population level between the amplitudes of event-related potential indices associated with auditory change detection (mismatch negativity) and visual selective attention (posterior contralateral N2) when elicited in separate tasks. This correlation persisted even when participants performed a visual task while disregarding simultaneous auditory stimuli. Interestingly, as visual attention demand increased, participants whose posterior contralateral N2 amplitude increased the most exhibited the largest reduction in mismatch negativity, suggesting a within-subject trade-off between the two processes. Taken together, our results suggest an intimate relationship and potential shared mechanism between auditory change detection and visual selective attention. We liken this to a total capacity limit that varies between individuals, which could drive correlated individual differences in auditory change detection and visual selective attention, and also within-subject competition between the two, with task-based modulation of visual attention causing within-participant decrease in auditory change detection sensitivity.

Central Auditory Changes Associated with Age-related Hearing Loss.

Objective. This study aimed to investigate age-related changes in cortical auditory evoked potentials (CAEPs) while considering three crucial factors: aging, high-frequency hearing loss and sensation level of the CAEP stimulus. Method. The electrophysiological and audiometric data of 71 elderly participants were analyzed using multiple regression analysis to investigate the association of CAEPs with the factors of aging, high-frequency hearing loss and sensation level of the CAEP test stimulus. Results. Aging was significantly associated with prolonged N1 and P2 latencies and reduced P2 amplitude. Elevated thresholds related to the sensation level of the CAEP stimulus were significantly associated with increased N1 and P2 amplitudes and decreased N1 latency. A significant relationship was detected between high-frequency hearing thresholds and the shortening of P2 latencies and the reduction of P2 amplitudes. Conclusion. The results of this study highlight the complex interplay of aging, high-frequency hearing loss and the sensation level of the CAEP stimulus on CAEP components in elderly people. These factors should be considered in future research using CAEPs to enhance overall understanding of auditory processing in the aging population.

Auditory Changes in Occupational Health Associated With Metabolic Diseases in Adult Workers.

The most common hearing losses in the population are associated with genetic conditions, use of ototoxic substances or medications, infectious diseases, metabolic diseases and chronic ear diseases and the association of exposure to occupational risks or the natural aging process. Verify the association between hearing loss in workers and metabolic diseases. Retrospective cross-sectional study with analysis of secondary data of subjects exposed to occupational noise and undergoing drug treatment for metabolic disease, attended in two occupational health clinics (C1 and C2) from January 2020 to December 2022, considering the data of reference examinations from the year 2005. Of the n = 97 subjects evaluated, 73.20% were male, exposed to occupational noise (64.90%), with medication use for treating cardiovascular diseases (89.70%). The most recurrent auditory complaint was tinnitus (28.90%), n = 53 subjects presented sensorineural hearing loss with a statistical association between the decline of hearing loss and medications used for metabolic and hormonal regulation. Here was a higher frequency in the use of medications for treating cardiovascular diseases with a risk of triggering or worsening hearing loss in these subjects and greater impairment and decline of hearing thresholds were observed in the results of C2.

Physiological characterization of a macaque model of presbycusis

Age-related hearing loss (presbycusis) is the leading cause of hearing loss worldwide, but current human studies do not separate this pathology from lifetime noise exposure. Laboratory macaques live in environments with minimal noise-induced hearing trauma and have long lifespans, making them optimal presbycusis models. We describe age-related auditory changes using two clinical, non-invasive physiological measures in aging macaques: distortion product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABRs). ABRs and DPOAEs were measured in anesthetized young (6–9 years old, n = 36 ears) and aging (26–35 years old, n = 20 ears) Macaca mulatta. ABR and DPOAE thresholds were elevated in aging subjects compared to young macaques at all tested frequencies. ABR thresholds were significantly correlated with age for frequencies >8 kHz, but DPOAE thresholds were not, a pattern likely attributable to a high-frequency ceiling effect for DPOAE measures. For frequencies <8 kHz, DPOAE thresholds showed significant correlation with age. However, this was not observed with ABR thresholds, suggesting differential sensitivity to age-related changes for auditory nerve and brainstem function compared to cochlear outer hair cell function. Ongoing analysis on temporal processing/adaptation metrics will further elucidate age-related changes. Future work will correlate these findings with histological analysis. [Work Supported by NIH R01-DC-015988.]

Long-term auditory monitoring in children with Alport syndrome based on different degrees of renal injury

Objective:To investigate long-term auditory changes and characteristics of Alport syndrome（AS） patients with different degrees of renal injury. Methods:Retrospectively analyzing clinical data of patients diagnosed AS from January 2007 to September 2022, including renal pathology, genetic detection and hearing examination. A long-term follow-up focusing on hearing and renal function was conducted. Results:This study included 70 AS patients, of which 33（25 males, 8 females, aged 3.4-27.8 years） were followed up, resulting in a loss rate of 52.9%.The follow-up period ranged from 1.1to 15.8 years, with 16 patients followed-up for over 10 years. During the follow-up, 10 patients presenting with hearing abnormalities at the time of diagnosis of AS had progressive hearing loss, and 3 patients with new hearing abnormalities were followed up, which appeared at 5-6 years of disease course. All of which were sensorineural deafness. While only 3 patients with hearing abnormalities among 13 patients received hearing aid intervention. Of these patients,7 developed end-stage renal disease（ESRD）, predominantly males （6/7）. The rate of long-term hearing loss was significantly different between ESRD group and non-ESRD group（P=0.013）. There was no correlation between the progression of renal disease and long-term hearing level（P>0.05）. kidney biopsies from 28 patients revealed varying degrees of podocyte lesion and uneven thickness of basement membrane. The severity of podocyte lesion was correlated with the rate of long-term hearing loss（P=0.048）, and there was no correlation with the severity of hearing loss（P>0.05）. Among 11 cases, theCOL4A5mutationwas most common （8 out of 11）, but there was no significant correlation between the mutation type and hearing phenotype（P>0.05）. Conclusion:AS patients exhibit progressive hearing loss with significant heterogeneity over the long-term.. THearing loss is more likely to occur 5-6 years into the disease course. Hearing abnormalities are closely related to renal disease status, kidney tissue pathology, and gene mutations, emphasizing the need for vigilant long-term hearing follow-up and early intervention.

Reduced MMN-indexed auditory change detection in a non-clinical high schizotypy sample.

Schizotypal traits include abnormalities in cognition, behavior, and interpersonal relationships that are similar, yet less severe than psychotic symptomology. It is estimated that approximately 5% of the general population displays psychotic symptoms and experiences that can be considered schizotypal in nature, but there is little research examining the neurological correlates of these traits. The mismatch negativity (MMN) event-related potential is an objective measure of auditory change detection derived from electroencephalography. The current study contributes to the limited body of evidence examining the neurobiological underpinnings of schizotypy in a non-clinical sample using the MMN. Participants were recruited from the general population and divided into high and low-schizotypy groups for comparison. Individuals with high schizotypal traits displayed reduced MMN amplitudes in response to frequency and location deviants, and longer MMN latencies in response to location deviants. Specific sub-traits of schizotypy were uniquely related to frequency and location amplitudes, suggesting the previously reported inconsistencies in the literature may be due to diverse samples and differing deviant tone types. Finally, impulsivity and sensation-seeking likely contributed to the slower processing seen in location deviance detection. Ultimately, the current results provide evidence that the neurobiological abnormalities seen in clinical populations of schizotypal personality disorder and psychosis also extend to non-clinical populations.

Histological Reaction in the Round Window Membrane after Cochlear Implant Insertion in Nonhuman Primates

Introduction: The primary objective of this article was to determine if any histological alterations occur in the round window (RW) and adjacent anatomical structures of an animal model with normal hearing when a cochlear implant (CI) electrode array is inserted. Furthermore, this article aims to relate these histological alterations to the auditory changes generated. Methods: Cochlear implantation was performed, following the principles of minimally traumatic surgery (MTS), in 15 ears of nonhuman primates (Macaca fascicularis) (Mf) with normal hearing. Auditory brainstem-evoked potentials (ABR) using clicks and tones were used prior to surgery and during a 6-month follow-up period. Histological evaluation was carried out, analyzing the position of the electrode array with respect to the round window membrane (RWM), its percentage of occupation and integrity, the presence of intracochlear damage, and the tissue reaction provoked, the latter of which was quantified in the temporal bones. Results: Surgery was performed on all 15 ears without relevant incidences. Regarding histology, the electrode array in the RW of all ears presented a lateral position with respect to the modiolus. No lesions affecting the integrity of the RW were observed. The mean value of the array’s occupation in the RW was 25%. Tissue reaction, in the form of fibrosis, was observed in all ears and more intensely in the trans-RWM and post-RWM areas. In all ears, the electrodes remained on the scala tympani. No profound hearing impairment was recorded in any ear, being the mean loss of 25.4 dB when comparing presurgical thresholds with those collected 6 months after implantation in ABR click and 24.4 dB in ABR tone burst. Conclusions: The animal model and Hybrid L-14 (HL14) electrode array were optimal for implementing a surgical technique similar to that routinely performed on humans. Mild histological alterations were observed in the round window membrane and adjacent anatomical structures from the insertion of a cochlear implant electrode array. Following the minimally invasive technique, levels of hearing preservation were satisfactory, reaching a pre-post difference of 25.4 dB in the ABR click and 24.4 dB for a high-frequency tone burst. Complete hearing impairment was not observed in either ear. Correlation between the severity of histological alterations and hearing changes recorded in the ABR studies was observed.

Doxycycline-Induced Intracranial Hypertension Presenting as Unilateral Pulsatile Tinnitus.

Pulsatile tinnitus (PT) is increasingly recognized as a cardinal symptom of idiopathic intracranial hypertension (IIH). However, clinicians should remain aware of other causes of nonidiopathic or secondary intracranial hypertension manifesting as PT. We present 2 patients with isolated PT (without accompanying headache, blurred vision, and papilledema) thought to be secondary to tetracycline-induced intracranial hypertension. To our knowledge, these are the first cases of PT as the presenting symptom of this condition. A 41-year-old female (body mass index [BMI] 29 kg/m2) with ocular rosacea was initially treated with minocycline. Shortly after transitioning to oral doxycycline and erythromycin eye ointment, she noted left-sided PT. Her PT resolved after discontinuing doxycycline. In a second case, a 39-year-old female (BMI 19 kg/m2) with acne presented with a three-year history of left-sided PT while on long-term oral doxycycline for many years. She denied visual or auditory changes and atypical headaches. MRI findings were concerning for intracranial hypertension. Three months later, the patient was seen by neuro-ophthalmology, with findings suggesting prior papilledema. The patient reported PT improvement after discontinuing doxycycline. This case series highlights 2 cases of isolated PT as the sole symptom of intracranial hypertension that resolved with tetracycline cessation. The presentation and unexpected improvement following tetracycline discontinuation are atypical compared with previous reports of tetracycline-induced intracranial hypertension. Clinicians should maintain a high index of suspicion for all types of intracranial hypertension (idiopathic and secondary), even in patients with a lower BMI. Current and prior medications should be reviewed when considering the etiology of intracranial hypertension.

Contribution of inter-trial phase coherence at theta, alpha, and beta frequencies in auditory change detection.

Auditory change detection is a pre-attentive cortical auditory processing ability. Many neurological and psychological disorders can lead to defects in this process. Some studies have shown that phase synchronization may be related to auditory discrimination. However, the specific contributions of phase synchronization at different frequencies remain unclear. We analyzed the electroencephalogram (EEG) data of 29 healthy adults using an oddball paradigm consisting of a standard stimulus and five deviant stimuli with varying frequency modulation patterns, including midpoint frequency transitions and linear frequency modulation. We then compared the peak amplitude and latency of inter-trial phase coherence (ITC) at the theta(θ), alpha(α), and beta(β) frequencies, as well as the N1 component, and their relationships with stimulus changes. At the same time, the characteristics of inter-trial phase coherence in response to the pure tone stimulation and chirp sound with a fine time-frequency structure were also assessed. When the stimulus frequency did not change relative to the standard stimulus, the peak latency of phase coherence at β and α frequencies was consistent with that of the N1 component. The inter-trial phase coherence at β frequency (β-ITC)served as a faster indicator for detecting frequency transition when the stimulus frequency was changed relative to the standard stimulus. β-ITC demonstrates temporal stability when detecting pure sinusoidal tones and their frequency changes, and is less susceptible to interference from other neural activities. The phase coherence at θ frequency could integrate the frequency and temporal characteristics of deviant into a single representation, which can be compared with the memory trace formed by the standard stimulus, thus effectively identifying auditory changes. Pure sinusoidal tone stimulation could induce higher inter-trial phase coherence in a smaller time window, but chirp sounds with a fine time-frequency structure required longer latencies to achieve phase coherence. Phase coherence at theta, alpha, and beta frequencies are all involved in auditory change detection, but play different roles in this automatic process. Complex time-frequency modulated stimuli require longer processing time for effective change detection.

Trait and State Anxiety Effects on Mismatch Negativity and Sensory Gating Event-Related Potentials.

We used the auditory roving oddball to investigate whether individual differences in self-reported anxiety influence event-related potential (ERP) activity related to sensory gating and mismatch negativity (MMN). The state-trait anxiety inventory (STAI) was used to assess the effects of anxiety on the ERPs for auditory change detection and information filtering in a sample of thirty-six healthy participants. The roving oddball paradigm involves presentation of stimulus trains of auditory tones with certain frequencies followed by trains of tones with different frequencies. Enhanced negative mid-latency response (130-230 ms post-stimulus) was marked at the deviant (first tone) and the standard (six or more repetitions) tone at Fz, indicating successful mismatch negativity (MMN). In turn, the first and second tone in a stimulus train were subject to sensory gating at the Cz electrode site as a response to the second stimulus was suppressed at an earlier latency (40-80 ms). We used partial correlations and analyses of covariance to investigate the influence of state and trait anxiety on these two processes. Higher trait anxiety exhibited enhanced MMN amplitude (more negative) (F(1,33) = 14.259, p = 6.323 × 10-6, ηp2 = 0.302), whereas state anxiety reduced sensory gating (F(1,30) = 13.117, p = 0.001, ηp2 = 0.304). Our findings suggest that high trait-anxious participants demonstrate hypervigilant change detection to deviant tones that appear more salient, whereas increased state anxiety associates with failure to filter out irrelevant stimuli.

P18 Bullous leukocytoclastic vasculitis in a patient with known undifferentiated autoimmune rheumatic disease

P18 Bullous leukocytoclastic vasculitis in a patient with known undifferentiated autoimmune rheumatic disease

Post-dural puncture headache combined with pneumocephalus secondary to vaginal delivery following epidural anesthesia: a case report

BackgroundPneumocephalus is rare in vaginal deliveries. Pneumocephalus may be asymptomatic or present with signs of increased intracranial pressure. However, parturients who received epidural anesthesia with air in their brains may experience low intracranial pressure headaches after giving birth, causing the diagnosis of pneumocephalus to be delayed. We report a case of a parturient who developed post-dural puncture headache combined with pneumocephalus secondary to vaginal delivery following epidural anesthesia.Case presentationA 24-year-old G1P0 Chinese woman at 38 weeks gestation was in labor and received epidural anesthesia using the loss of resistance to air technique and had a negative prior medical history.She presented with postural headache, neck stiffness and auditory changes 2 h after vaginal delivery. The head non-contrast computed tomography revealed distributed gas density shadows in the brain, indicating pneumocephalus. Her headache was relieved by bed rest, rehydration, analgesia, and oxygen therapy and completely disappeared after 2 weeks of postpartum bed rest.ConclusionsThis is the first report that positional headaches after epidural anesthesia may not indicate low intracranial pressure alone; it may combine with pneumocephalus, particularly when using the loss of resistance to air technique. At this moment, head computed tomography is essential to discover other conditions like pneumocephalus.

Mismatch negativity as a marker of auditory pattern separation.

To what extent does incidental encoding of auditory stimuli influence subsequent episodic memory for the same stimuli? We examined whether the mismatch negativity (MMN), an event-related potential generated by auditory change detection, is correlated with participants' ability to discriminate those stimuli (i.e. targets) from highly similar lures and from dissimilar foils. We measured the MMN in 30 young adults (18-32years, 18 females) using a passive auditory oddball task with standard and deviant 5-tone sequences differing in pitch contour. After exposure, all participants completed an incidental memory test for old targets, lures, and foils. As expected, participants at test exhibited high sensitivity in recognizing target items relative to foils and lower sensitivity in recognizing target items relative to lures. Notably, we found a significant correlation between MMN amplitude and lure discrimination, but not foil discrimination. Our investigation shows that our capacity to discriminate sensory inputs at encoding, as measured by the MMN, translates into precision in memory for those inputs.

Long-term phonemic representations become audiovisual by mid-childhood

In earlier work with adults, we showed that long-term phonemic representations are audiovisual, meaning that they contain information on typical mouth shape during articulation. Many aspects of audiovisual processing have a prolonged developmental course, often not reaching maturity until late adolescence. In this study, we examined the status of phonemic representations in two groups of children – 8-9-year-olds and 11-12-year-olds. We used the same audiovisual oddball paradigm as in the earlier study with adults (Kaganovich and Christ, 2021). On each trial, participants saw a face and heard one of two vowels. One vowel occurred frequently (standard), while another occurred rarely (deviant). In one condition (neutral), the face had a closed, non-articulating mouth. In the other condition (audiovisual violation), the mouth shape matched the frequent vowel. Although stimuli were audiovisual in both conditions, we hypothesized that identical auditory changes would be perceived differently by participants. Namely, in the neutral condition, deviants violated only the audiovisual pattern specific to each experimental block. By contrast, in the audiovisual violation condition, deviants additionally violated long-term representations for how a speaker's mouth looks during articulation. We compared the amplitude of MMN and P3 components elicited by deviants in the two conditions. In the 11-12-year-old group, the pattern of neural responses was similar to that in adults – namely, they had a larger MMN component in the audiovisual compared to neutral condition, with no major difference in the P3 amplitude. In contrast, in the 8-9-year-old group, we saw a posterior MMN in the neutral condition only and a larger P3 in the audiovisual violation compared to the neutral condition. The larger P3 in the audiovisual violation condition suggests that younger children did perceive deviants as being more attention-grabbing when they violated the typical combination of sound and mouth shape. Yet, at this age, the earlier, more automatic stages of phonemic processing indexed by the MMN component may not yet encode visual speech elements the same way they do in older children and adults. We conclude that phonemic representations do not become audiovisual until 11–12 years of age.

Increased central auditory gain in 5xFAD Alzheimer's disease mice as an early biomarker candidate for Alzheimer's disease diagnosis.

Alzheimer's Disease (AD) is a neurodegenerative illness without a cure. All current therapies require an accurate diagnosis and staging of AD to ensure appropriate care. Central auditory processing disorders (CAPDs) and hearing loss have been associated with AD, and may precede the onset of Alzheimer's dementia. Therefore, CAPD is a possible biomarker candidate for AD diagnosis. However, little is known about how CAPD and AD pathological changes are correlated. In the present study, we investigated auditory changes in AD using transgenic amyloidosis mouse models. AD mouse models were bred to a mouse strain commonly used for auditory experiments, to compensate for the recessive accelerated hearing loss on the parent background. Auditory brainstem response (ABR) recordings revealed significant hearing loss, a reduced ABR wave I amplitude, and increased central gain in 5xFAD mice. In comparison, these effects were milder or reversed in APP/PS1 mice. Longitudinal analyses revealed that in 5xFAD mice, central gain increase preceded ABR wave I amplitude reduction and hearing loss, suggesting that it may originate from lesions in the central nervous system rather than the peripheral loss. Pharmacologically facilitating cholinergic signaling with donepezil reversed the central gain in 5xFAD mice. After the central gain increased, aging 5xFAD mice developed deficits for hearing sound pips in the presence of noise, consistent with CAPD-like symptoms of AD patients. Histological analysis revealed that amyloid plaques were deposited in the auditory cortex of both mouse strains. However, in 5xFAD but not APP/PS1 mice, plaque was observed in the upper auditory brainstem, specifically the inferior colliculus (IC) and the medial geniculate body (MGB). This plaque distribution parallels histological findings from human subjects with AD and correlates in age with central gain increase. Overall, we conclude that auditory alterations in amyloidosis mouse models correlate with amyloid deposits in the auditory brainstem and may be reversed initially through enhanced cholinergic signaling. The alteration of ABR recording related to the increase in central gain prior to AD-related hearing disorders suggests that it could potentially be used as an early biomarker of AD diagnosis.

Acoustic and Semantic Processing of Auditory Scenes in Children with Autism Spectrum Disorders

Purpose: Processing real-world sounds requires acoustic and higher-order semantic information. We tested the theory that individuals with autism spectrum disorder (ASD) show enhanced processing of acoustic features and impaired processing of semantic information. Methods: We used a change deafness task that required detection of speech and non-speech auditory objects being replaced and a speech-in-noise task using spoken sentences that must be comprehended in the presence of background speech to examine the extent to which 7–15 year old children with ASD (n = 27) rely on acoustic and semantic information, compared to age-matched (n = 27) and IQ-matched (n = 27) groups of typically developing (TD) children. Within a larger group of 7–15 year old TD children (n = 105) we correlated IQ, ASD symptoms, and the use of acoustic and semantic information. Results: Children with ASD performed worse overall at the change deafness task relative to the age-matched TD controls, but they did not differ from IQ-matched controls. All groups utilized acoustic and semantic information similarly and displayed an attentional bias towards changes that involved the human voice. Similarly, for the speech-in-noise task, age-matched–but not IQ-matched–TD controls performed better overall than the ASD group. However, all groups used semantic context to a similar degree. Among TD children, neither IQ nor the presence of ASD symptoms predict the use of acoustic or semantic information. Conclusion: Children with and without ASD used acoustic and semantic information similarly during auditory change deafness and speech-in-noise tasks.