Middle Latency Response Research Articles

The Effect of Different Adaptation Formulas on Mid-Latency Auditory Evoked Potentials in Adults with Hearing Aids.

We were conducting this study to evaluate the effects of different hearing aid adaptation formulas on middle latency responses (MLR) in adult hearing aid users. The study included 72 participants: those with moderate hearing loss using hearing aids with two different formulas for the last year, those with moderate hearing loss not using hearing aids, and those without hearing loss. Sixteen participants using NAL-NL1 and NAL-RP formulas were Group 1; twenty using NAL-NL2 and DSL formulas were Group 2; fifteen with hearing loss not using devices were Group 3; and twenty-one without hearing loss were Group 4. We obtained and compared MLR responses, including Na latency, Pa latency, and Na-Pa amplitude. Group 1 mean Na-Pa amplitude value was found to be higher than Group 2 (p = 0.001). No significant difference was observed between Group 1 and Group 2 in terms of Na latency and Pa latency values (p = 0.001; p = 0.035). It was observed that the mean Na-Pa amplitude values in Group 1 and Group 2 were higher than Group 3 (p = 0.001), but this elevation reached the level of statistical significance only in Group 1. No difference was observed between Group 1, Group 2, and Group 3 in terms of Na latency and Pa latency values (p = 0.001; p = 0.035). Compared with those without hearing loss (Group 4), participants with hearing loss (Group 1, Group 2, and Group 3) had longer Na latency and Pa latency values (p = 0.001; p = 0.035), and Na-Pa amplitudes were lower (p = 0.001). The effect of current (tested) hearing aid usage time on Na latency, Pa latency, and Na-Pa amplitude values of Group 1 and Group 2 was not observed. In all groups, there was a positive correlation between audiometric airway/bone conduction pure tone averages and speech acquisition threshold values, Na latency and Pa latency values, and a negative correlation between Na-Pa amplitude values. In all groups, there was a negative correlation between speech discrimination scores and Na and Pa latency values, as well as a positive correlation between Na and Pa amplitude values. There was a positive correlation between age and Pa latency values in all groups, as well as a negative correlation between Na and Pa amplitude values. Middle latency responses are affected by the presence of hearing loss, the use of hearing aids, and different hearing aid adaptation formulas. MLR measurements with a hearing aid can be used as an objective test to evaluate the benefit of hearing aid use.

Evaluation of auditory middle latency response during the menstrual cycle

Aim: The hormone levels during the menstrual cycle, directly and indirectly, affect the hearing system. In our study, it was aimed to examine the effects of changing hormone levels during the menstrual cycle on auditory middle latency responses in healthy individuals with different stimuli types and the psychosomatic effects of premenstrual complaints on auditory performance. Methods: In the study, 20 healthy women aged 18-35 years, with regular menstrual cycles and no auditory or vestibular complaints were evaluated for auditory middle latency responses with click and level-specific (LS) CE-Chirp® stimuli during the menstruation period of the follicular phase (1-5 day, menstrual phase), the ovulation phase (14-17 day) and the luteal phase (21-28 day). To evaluate the effect of premenstrual complaints on auditory performance, the participants were asked 5 questions. Results: In the auditory middle latency assessment with click stimuli, a statistically larger Na-Pa amplitude was obtained in the menstruation phase compared to the ovulation phase in both ears. In the auditory middle latency evaluation with LS CE-Chirp® stimulus, statistically shortened Nb latencies were obtained in the right ear in the menstruation phase compared to the ovulation phase. Conclusion: Although the clear effect of changing gonadal hormone levels on auditory evoked middle latency responses could not be determined, the findings show that neural transmission increases in the menstrual phase when the estrogen level is low. Click stimulus is more sensitive to hormonal changes, and the use of click stimulus has been recommended in the later side of lesion studies. In our study, no psychosomatic effect of complaints in the premenstrual period on auditory performance was observed.

Investigating the Feasibility of Gap Prepulse Inhibition by Auditory Middle Latency Responses in Healthy Subjects

Background and Aim: Gap Prepulse Inhibition (GPI) is a type of Prepulse Inhibition (PPI) in which a gap is used as a prepulse. This study was conducted to investigate the silence gap effect on Auditory Middle Latency Response (AMLR) inhibition in normal subjects. Methods: In this study, 25 participants with normal hearing and no history of tinnitus were included. AMLR was recorded in response to stimuli with gap and without gap in two background noises of 2 and 8 kHz at two electrode locations Fz and Cz and then, gap prepulse inhibition for Na-Pa, Pa-Nb, Nb-Pb and Pb-Nc amplitude with Use of responses to stimuli with and without gap was calculated. Results: The results showed that the mean amplitudes of all four AMLR indices decreased in response to the stimuli with gap and this decrease was more and statistically significant in 8 kHz background noise (p≤0.001). Conclusion: According to the results of this study, it seems that in future studies, PPI of Na-Pa and Pb-Nc amplitudes can be used as main indicators and PPI of Pa-Nb and Nb-Pb amplitudes as alternative indicators in the PPI paradigm in tinnitus diagnosis. Keywords: Prepulse inhibition; tinnitus; auditory middle latency responses

Effects of Korean red ginseng on auditory, cognitive, and liver functions in a naturally aged mouse model

BackgroundKorean Red Ginseng and ginsenosides have been studied for their efficacy against various diseases, including those related to aging. However, most aging studies use D-galactose to induce aging, which often does not accurately represent natural aging. This study aimed to verify improvements in auditory, cognitive, and liver function through administering red ginseng to an 18-month-old naturally aging mouse model. MethodsAuditory function was assessed using Auditory Brainstem Response (ABR) and Auditory Middle Latency Response (AMLR). Cognitive function was evaluated electrophysiologically with P300 and mismatch negativity (MMN), and behaviorally using the Y-maze. Additionally, biochemical tests and histological analysis were conducted to assess liver function. The effects of red ginseng on gene expression regulation were also examined in the cochlea, auditory cortex, and liver, focusing on age-related disease processes. ResultsRed ginseng significantly decreased hearing thresholds and improved central auditory function. It also enhanced cognitive behavior and function in response to external stimulation. Furthermore, red ginseng regulated alkaline phosphatase (ALP), albumin (Alb), and total protein (TP) levels, notably decreasing aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Hematoxylin and eosin (H&E) staining of liver tissue showed significant improvement in fat droplets. These effects appear to be mediated by the regulation of aging-related genes Dec, c-Jun, Stat5b, and Lims2. ConclusionThese results suggest that red ginseng improves auditory, cognitive, and liver functions in a naturally aged mouse model.

Therapeutic Function of Liraglutide for Mitigation of Blast-Induced Hearing Damage: An Initial Investigation in Animal Model of Chinchilla.

Auditory injuries induced by repeated exposures to blasts reduce the operational performance capability and the life quality of military personnel. The treatment for blast-induced progressive hearing damage is lacking. We have recently investigated the therapeutic function of liraglutide, a glucagon-like peptide-1 receptor agonist, to mitigate blast-induced hearing damage in the animal model of chinchilla, under different blast intensities, wearing earplugs (EPs) or not during blasts, and drug-treatment plan. The goal of this study was to investigate the therapeutical function of liraglutide by comparing the results obtained under different conditions. Previous studies on chinchillas from two under-blast ear conditions (EP/open), two blast plans (G1: 6 blasts at 3-5 psi or G2:3 blasts at 15-25 psi), and three treatment plans (blast control, pre-blast drug treatment, and post-blast drug treatment) were summarized. The auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and middle latency response (MLR) recorded within 14 days after the blasts were used. Statistical analysis was performed to evaluate the effect of liraglutide under different conditions. ABR threshold shifts indicated that the conditions of the EP and open ears were substantially different. Results from EP chinchillas indicated that the pre-blast treatment reduced the acute ABR threshold elevation on the day of blasts, and the significance of such an effect increased with the blast level. Liraglutide-treated open chinchillas showed lower ABR threshold shifts at the later stage of the experiment regardless of the blast levels. The DPOAE was less damaged after G2 blasts compared to G1 when pre-blast liraglutide was administrated. Lower post-blast MLR amplitudes were observed in the pre-blast treatment groups. This study indicated that the liraglutide mitigated the blast-induced auditory injuries. In EP ears, the pre-blast administration of liraglutide reduced the severity of blast-induced acute damage in ears with EP protection, especially under G2. In animals with open ears, the effect of liraglutide on the restoration of hearing increased with time. The liraglutide potentially benefits post-blast hearing through multiple approaches with different mechanics.

Phenotypic spectrum of tinnitus patients bearing rare ANK2 gene variants

PurposeTo describe the clinical, audiological, and psychometric features observed in patients with chronic tinnitus and rare variants in the ANK2 gene.MethodsWe report a case series of 12 patients with chronic tinnitus and heterozygous variants in the ANK2 gene. Tinnitus phenotyping included audiological (standard and high-frequency audiometry, Auditory Brainstem Responses (ABR) and Auditory Middle Latency Responses (AMLR)), psychoacoustic and psychometric assessment by a Visual Analog Scale (VAS) for tinnitus annoyance, the Tinnitus Handicap Inventory (THI), the test on Hypersensitivity to Sound (THS-GÜF), the Patient Health Questionnaire (PHQ-9), the Hospital Anxiety and Depression Scale (HADS) and the Montreal Cognitive Assessment (MoCA).ResultsAll patients reported a persistent, unilateral noise-type tinnitus, mainly described as white noise or narrowband noise. Seven patients (58%) were considered to have extreme phenotype (THI score > 76), and all patients reported some degree of hyperacusis (THS-GÜF score > 18 in 75% of patients). Seven patients scored MoCA < 26, regardless of the age reported, suggesting a mild cognitive disorder. ABR showed no significant differences in latencies and amplitudes between ears with or without tinnitus. Similarly, the latencies of Pa, Pb waves, and NaPa complex in the AMLR did not differ based on the presence of tinnitus. However, there were statistical differences in the amplitudes of Pa waves in AMLR, with significantly greater amplitudes observed in ears with tinnitus.ConclusionPatients with ANK2 variants and severe tinnitus exhibit an endophenotype featuring hyperacusis, persistent noise-like tinnitus, high-frequency hearing loss, and decreased amplitudes in AMLR. However, anxiety, depression, and cognitive symptoms vary among individuals.

My Perspective: Auditory Evoked Potentials Using Speech

Purpose: The purpose of this tutorial is to clarify the use of speech sounds as stimuli for auditory evoked potentials and how these might contribute to our understanding of speech, language, learning, and hearing disorders. Speech-evoked auditory brainstem responses (ABRs), auditory steady-state responses, auditory middle latency responses, mismatch negativity, P300, cortical onset responses, and the acoustic change complex are reviewed. Method: The author drew upon her scholarship in this area from over 4 decades of research and teaching to summarize the major findings when using speech stimuli to evoke auditory potentials that have been used in clinical contexts. Results: Speech-evoked auditory potentials contribute to our understanding of how the brain processes the acoustic features of speech sounds, providing information that is complementary to psychophysical tests. When psychophysical tests cannot be performed owing to neurodevelopmental immaturity or disability, or cognitive disability, speech-evoked auditory potentials may be used to estimate the benefit of amplification or implantation for speech, language, and hearing. Conclusions: The benefit of using auditory evoked potentials for evaluation is that they provide insight into the brain mechanisms underlying hearing and listening disorders that audiologists aim to treat. While we can use the known correlations between perceptual and electrophysiological responses for “cross-checking” our evaluation results, examining when discrepancies occur is also especially meaningful. For example, the complex ABR reveals subcortical issues in temporal processing that would not be evident in ABRs to clicks or tone bursts, nor in behavioral testing. P300 can document slower neural processing of speech stimuli that may be relevant to the rehabilitation of older adults, even when word recognition scores appear to be congruent with the pure-tone audiogram. In these ways, auditory evoked potentials for speech provide audiologists with tools for demonstrating to clients how their brain responds to speech and opening the conversation for rehabilitation.

Habituation disorders in auditory middle latency response of persistent postural-perceptual dizziness patients.

To study habituation disorders in auditory middle latency response (AMLR) to repetitive stimuli of persistent postural-perceptual dizziness (PPPD) patients. Twenty-eight PPPD (10 men and 18 women, mean 59.5 years of age, 26-81 years of age) were enrolled. For comparison, data of 13 definite vestibular migraine (VM) patients (3 men, 10 women, mean age 45.5), 13 definite unilateral Meniere's disease (MD) patients (2 men, 11 women, mean age 50.6), and 8 healthy control (HC) subjects (2 men, 6 women, mean age 37.1) in the previous study were utilized. The electrodes were placed on the vertex and the spinal process of the fifth cervical vertebra. Clicks (0.1 msec, 70 dB nHL) were binaurally presented and averaged (800 times). Averaged responses were divided into 4 sets (S1 to S4) according to the temporal order. As peaks, Na, and Pa were identified, and relative Na-Pa amplitudes in S2-S4 to S1 were analyzed. The mean relative amplitude of PPPD patients showed lack of habituation (potentiation) as shown in VM patients, although the extent of potentiation was weaker than VM. Comparison of relative S4 amplitudes showed significant differences among the 4 groups (p = 0.0013 one-way ANOVA), Multiple comparison revealed significant differences between PPPD and MD (p = 0.0337 Dunnet's test). PPPD patients showed lack of habituation (potentiation) of Na-Pa amplitude in AMLR to repetitive stimuli. Lack of habituation (potentiation) might be associated with sensory processing disorders in PPPD.

Comprehensive behavioral and physiologic assessment of peripheral and central auditory function in individuals with mild traumatic brain injury

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.

Evoked Potentials by Tone Burst on the Auditory Cortices in Cats -Comparison of Off Responses in Awake and Anesthetized Conditions.

Auditory Brainstem Response (ABR) recording in awake is essential to detect off-responses. This study clarified whether after-termination responses on ABR were offset responses, off-responses or a mixture of the two. Evoked potentials in the auditory cortex of cats in response to tone burst stimuli were recorded, and off responses were examined with chronically implanted electrodes. When the fall time at the end of sound stimuli was 5ms or longer, the amplitude of click responses was extremely small. Under this condition, evoked potentials in response to two types of tone bursts (long and short) were recorded.By calculating the differences in evoked potentials between the two-tone bursts, off responses were separated. Off responses were generated during wakefulness by auditory cortex stimulation but were not observed under anesthesia. Pronounced off responses, which were middle latency responses exhibiting bis positive waves, were obtained in response to sound stimuli with a frequency of 2 kHz or higher. Vertex stimulation did not induce off responses either during wakefulness or under anesthesia. Off responses are derived from synchronous responses of neurons in the auditory cortex, which are generated when the neurons detect attenuation in the stimulus strength at the end of tone burst stimuli.

Mitigation ofHearing Damage With Liraglutide Treatment inChinchillas After Repeated Blast Exposures at Mild-TBI.

Although hearing protection devices (HPDs) have been widely used during training and combat, over one million veterans experience service-connected hearing loss. Hearing damage has been reported to be associated with blast-induced mild traumatic brain injury (mTBI) and there is a lack of understanding and treatment. Liraglutide is a glucagon-like peptide-1 receptor agonist and a potential treatment for TBI-induced memory deficits. This study aims to investigate the function of the liraglutide to prevent damage and facilitate hearing restoration in chinchillas exposed to multiple high-intensity, mTBI-level blasts. Chinchillas were divided into three treatment groups: blast control, pre-blast drug treatment, and post-blast drug treatment. On day 1, the chinchilla ears were protected by HPDs and exposed to three blasts with peak pressure levels of 15-25 psi. The auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and middle latency response (MLR) were recorded pre- and post-blast on day 1 and on days 4, 7, 14, and 28. Substantial acute damage was observed and progressively recovered in chinchillas after the blast exposures. The pre-blast treatment group exhibited the lowest elevation of the ABR threshold and reduction of the wave I amplitude on day 1 after blasts. The liraglutide treatment insignificantly facilitated the recovery of the DPOAE levels and ABR thresholds on days 14 and 28. The pre-blast treatment chinchillas showed reduced MLR amplitudes on days 4 and 7. This study indicated that the pre-blast liraglutide administration provided damage protection against blasts in addition to the HPDs. Current evidence suggests that the effect of liraglutide is more prominent in the early phase of the experiment.

Frequency and Time Domain Analysis of EEG Based Auditory Evoked Potentials to Detect Binaural Hearing in Noise

Hearing loss is a prevalent health issue that affects individuals worldwide. Binaural hearing refers to the ability to integrate information received simultaneously from both ears, allowing individuals to identify, locate, and separate sound sources. Auditory evoked potentials (AEPs) refer to the electrical responses that are generated within any part of the auditory system in response to auditory stimuli presented externally. Electroencephalography (EEG) is a non-invasive technology used for the monitoring of AEPs. This research aims to investigate the use of audiometric EEGs as an objective method to detect specific features of binaural hearing with frequency and time domain analysis techniques. Thirty-five subjects with normal hearing and a mean age of 27.35 participated in the research. The stimuli used in the current study were designed to investigate the impact of binaural phase shifts of the auditory stimuli in the presence of noise. The frequency domain and time domain analyses provided statistically significant and promising novel findings. The study utilized Blackman windowed 18 ms and 48 ms pure tones as stimuli, embedded in noise maskers, of frequencies 125 Hz, 250 Hz, 500 Hz, 750 Hz, 1000 Hz in homophasic (the same phase in both ears) and antiphasic (180-degree phase difference between the two ears) conditions. The study focuses on the effect of phase reversal of auditory stimuli in noise of the middle latency response (MLR) and late latency response (LLR) regions of the AEPs. The frequency domain analysis revealed a significant difference in the frequency bands of 20 to 25 Hz and 25 to 30 Hz when elicited by antiphasic and homophasic stimuli of 500 Hz for MLRs and 500 Hz and 250 Hz for LLRs. The time domain analysis identified the Na peak of the MLR for 500 Hz, the N1 peak of the LLR for 500 Hz stimuli and the P300 peak of the LLR for 250 Hz as significant potential markers in detecting binaural processing in the brain.

Development of Machine-Learning Models for Tinnitus-Related Distress Classification Using Wavelet-Transformed Auditory Evoked Potential Signals and Clinical Data.

Tinnitus is a highly prevalent condition, affecting more than 1 in 7 adults in the EU and causing negative effects on sufferers' quality of life. In this study, we utilised data collected within the "UNITI" project, the largest EU tinnitus-related research programme. Initially, we extracted characteristics from both auditory brainstem response (ABR) and auditory middle latency response (AMLR) signals, which were derived from tinnitus patients. We then combined these features with the patients' clinical data, and integrated them to build machine learning models for the classification of individuals and their ears according to their level of tinnitus-related distress. Several models were developed and tested on different datasets to determine the most relevant features and achieve high performances. Specifically, seven widely used classifiers were utilised on all generated datasets: random forest (RF), linear, radial, and polynomial support vector machines (SVM), naive bayes (NB), neural networks (NN), and linear discriminant analysis (LDA). Results showed that features extracted from the wavelet-scattering transformed AMLR signals were the most informative data. In combination with the 15 LASSO-selected clinical features, the SVM classifier achieved optimal performance with an AUC value, sensitivity, and specificity of 92.53%, 84.84%, and 83.04%, respectively, indicating high discrimination performance between the two groups.

Hearing protection and damage mitigation in Chinchillas exposed to repeated low-intensity blasts

Repeated exposures to blast overpressure (BOP) introduce hearing complaints in military service members even with the use of hearing protection devices (HPDs). Although epidemiology and animal studies have been performed to investigate the damage formation mechanism of blast-induced hearing damage, there is still a lack of understanding and therapeutic solutions, especially for HPD-protected ears. Recent studies revealed the potential therapeutic function of liraglutide, a glucagon-like peptide-1 receptor agonist, to facilitate post-blast hearing restoration in chinchillas. This study is a continuation and summary of the previous studies performed by Jiang et al. (2021, 2022) to investigate the damage mitigation function of liraglutide treatment in chinchillas with open and protected ears after repeated low-intensity blast exposures within 28 days of observation.Chinchillas were divided into six experimental groups: pre-blast treatment, post-blast treatment, and blast control with ears open or protected by earplug (EP). All animals were exposed to six consecutive blasts at the level of 3–5 psi (21–35 kPa) on Day 1. Hearing function tests including auditory brainstem response (ABR), distortion product otoacoustic emission (DPOAE), and middle latency response (MLR) were performed on Day 1 (pre- and post-blast) and Days 4, 7, 14, and 28 after blast exposure.Results indicated that the damage mitigation function of the liraglutide treatment in the open-ear chinchillas was reflected by the significantly lower ABR threshold shifts in the drug treatment groups than in the blast controls. In EP groups, the higher ABR wave I/V ratio and lower MLR amplitude observed in the drug-treated chinchillas suggested that the post-blast hyperactivities in the auditory system might be potentially ameliorated by the liraglutide treatment. The 28-day-long experiment showed the effect of liraglutide treatment increased with time in both open and EP groups.This study demonstrated that the use of HPDs prevented the blast-induced complications in the middle ear and reduced the damage caused in the central auditory system. The liraglutide treatment showed an effect increasing with time and different outcomes in open and EP chinchillas. This innovation in the animal model of chinchilla provides insights to investigate subtle changes in the higher-level structures of the auditory system.

Diagnosis of Patients Presenting with Vertigo, Headache, and Epileptic Seizure: Evaluating Vestibular Patients by Using Cervical Vestibular Evoked Myogenic Potential and Auditory Middle Latency Responses in the Clinical Setting.

Migraine and vertigo are common complaints seen in clinical practice, and in a few such cases, we also find epileptic manifestations, including migraine-triggered seizures. Currently, patients presenting with vertigo and headache are diagnosed according to established diagnostic criteria for Meniere's disease, vestibular migraine, or vestibular migraine/Meniere's disease overlapping syndrome. In addition to using those diagnostic criteria and the patient's history, cervical vestibular evoked myogenic potential and auditory middle latency responses are useful tools to better understand the physiological background of these patients and also to confirm the diagnosis. Here we report 2 cases: 1 of vestibular migraine/ Meniere's disease overlapping syndrome and 1 of vestibular migraine with epileptic manifestations. Each patient showed potentiation (lack of habituation) in auditory middle latency response, and each showed endolymphatic hydrops in cervical vestibular evoked myogenic potential. The potentiation in auditory middle latency response might be attributable to neuronal hyperexcitability in those patients with migraine or epilepsy, and neurogenic inflammation caused by migraine episodes might affect inner ear function.

Study of aged central auditory function using the auditory middle latency response

ObjectiveInvestigate the auditory function of the elderly using the middle latency potentials. MethodologyGroup 1 (G1): 20 healthy individuals of both genders, older than 60 years, without hearing loss. Group 2 (G2): 20 healthy individuals of both sexes, older than 60 years, with hearing loss in frequencies from 4 to 8 kHz. Potential recording was performed with unilateral and bilateral stimulation and the Binaural Interaction Component was calculated. ResultsNa latency in C3A1 was greater in the stimulation of the right ear in G2 and the amplitude of Na-Pa was greater in the stimulation of the right ear and recording in C3A1 in G1. The latency of the Pa component was higher in the stimulation of the right ear recorded in C4A2. The Pb component in G2 by bilateral stimulation and recorded in C4A2 had higher latency. The first and second negative and positive peaks presented greater amplitude in G1. In C3A1, the 1st negative peak was more negative in G1 and the 2nd positive peak showed greater amplitude in C4A2 in both groups. ConclusionThe transmission of auditory information to the primary auditory cortex is impaired with aging, especially in unilateral stimulation, reinforced by losses in elderly people with peripheral hearing loss, such as in the binaural interaction at the cortical and subcortical levels. Thus, the AMLR has shown to be a sensitive examination to investigate neuroauditory disorders in the elderly, especially related to high-frequency hearing loss and primary auditory cortex dysfunctions caused by the aging process.

Auditory middle latency responses and hearing skills in adults

RESUMO Objetivo: comparar a latência e a amplitude dos componentes Na, Pa, Nb e Pb do Potencial Evocado Auditivo de Média Latência em adultos com e sem alterações em habilidades auditivas, bem como analisar a sensibilidade e a especificidade dos valores de corte de 30% e 50% para o Efeito de Orelha. Métodos: compuseram a amostra 32 indivíduos de ambos os sexos e sem perda auditiva, sendo subdivididos em Grupo 1 (16 indivíduos sem alterações em habilidades auditivas) e Grupo 2 (16 indivíduos com alterações em habilidades auditivas). Todos os participantes foram submetidos a uma avaliação audiológica e aos Potenciais Evocados Auditivos de Tronco Encefálico de Média Latência. O teste ANOVA foi utilizado na análise dos dados, considerando significantes os valores de p menores ou iguais a 0,05. Resultados: foi observada diferença estatisticamente significante apenas na amplitude de Na e Pa, quando Grupo 1 e Grupo 2 foram comparados. Esta diferença foi observada nas ondas A1C3 e A2C3. Na análise de sensibilidade e especificidade do Potencial Evocado Auditivo de Média Latência, observou-se que o valor de corte de 50% apresentou um melhor equilíbrio entre os critérios de sensibilidade e especificidade. Conclusão: os indivíduos adultos com alterações nas habilidades auditivas apresentaram menor amplitude de resposta nos componentes Na e Pa das ondas geradas no hemisfério esquerdo. O valor de corte de 50% apresentou um melhor equilíbrio na análise do Efeito de Orelha para a contribuição no diagnóstico de alterações de habilidades auditivas.

Potencial evocado auditivo de média latência e habilidades auditivas em adultos

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.

Development and Evaluation of Automated Tools for Auditory-Brainstem and Middle-Auditory Evoked Potentials Waves Detection and Annotation.

Auditory evoked potentials (AEPs) are brain-derived electrical signals, following an auditory stimulus, utilised to examine any obstructions along the brain neural-pathways and to diagnose hearing impairment. The clinical evaluation of AEPs is based on the measurements of the latencies and amplitudes of waves of interest; hence, their identification is a prerequisite for AEP analysis. This process has proven to be complex, as it requires relevant clinical experience, and the existing software for this purpose has little practical use. The aim of this study was the development of two automated annotation tools for ABR (auditory brainstem response)- and AMLR (auditory middle latency response)-tests. After the acquisition of 1046 raw waveforms, appropriate pre-processing and implementation of a four-stage development process were performed, to define the appropriate logical conditions and steps for each algorithm. The tools' detection and annotation results, regarding the waves of interest, were then compared to the clinicians' manual annotation, achieving match rates of at least 93.86%, 98.51%, and 91.51% respectively, for the three ABR-waves of interest, and 93.21%, 92.25%, 83.35%, and 79.27%, respectively, for the four AMLR-waves. The application of such tools in AEP analysis is expected to assist towards an easier interpretation of these signals.

Intensity and inter-stimulus-interval effects on human middle- and long-latency auditory evoked potentials in an unpredictable auditory context.

It is not known how Auditory-Evoked Responses (AERs) comprising Middle Latency Responses (MLRs) and Long Latency Responses (LLRs) are modulated by stimulus intensity and inter-stimulus interval (ISI) in an unpredictable auditory context. Further, intensity and ISI effects on MLR and LLR have never been assessed simultaneously in the same humans. To address this important question, thirty participants passively listened to a random sequence of auditory clicks of three possible intensities (65, 75, and 85 dB) at five possible ISI ranges (0.25 to 0.5s, 0.5 to 1s, 1 to 2s, 2 to 4s, 4 to 8s) over four to seven one-hour sessions while EEG was recorded. P0, Na, Pa, Nb, and Pb MLR peaks and N1 and P2 LLR peaks were measured. MLRs P0 (p=.005), Pa (p=.021), and Pb (p=<.001) were modulated by intensity, while only MLR Pb (p=<.001) was modulated by ISI. LLR N1 and P2 were modulated by both intensity and ISI (all p values < .001). Intensity and ISI interacted at Pb, N1, and P2 (all p values < .001), with greater intensity effects at longer ISIs and greater ISI effects at louder intensities. Together, these results provide a comprehensive picture of intensity and ISI effects on AER across the entire thalamocortical auditory pathway, while controlling for stimulus predictability. Moreover, they highlight P0 as the earliest MLR response sensitive to stimulus intensity and Pb (~50 ms) as the earliest cortical response coding for ISIs above 250 ms and showing an interdependence between intensity and ISI effects.