Middle Latency Response Research Articles

Long Term Test-Retest Reliability of Auditory Brainstem Response (ABR) and Middle Latency Response (MLR)

Objective: To study the variability of auditory brainstem response (ABR) and middle latency response (MLR) over a long term period. Methods: 50 normal hearing subjects participated in the study. All the subjects were tested at 3 months, 6 months and 12 months of the initial testing. The absolute latencies and interpeak latencies of ABR waves and amplitudes & latencies of waves Na and Pa of MLR were measured. Results: The Repeated measure ANOVA did not reveal any statistically significant difference (p>0.05) between interpeak latencies of wave I-III, III-V and I-V across the four visits. The amplitude of MLR wave Pa showed no significant difference across four visits. However significant difference (p<0.05) across visits was observed for latency of wave Na. Conclusions: The absolute latencies of wave III & V and the interpeak latencies of waves I-III, III-V and I-V have good test retest reliability. Reliability of wave I however has not been established. Amplitude of wave Pa has good test retest reliability. Significance: The ABR and MLR can be used as monitoring tools in a number of cases like neurodegenerative disorders, progressive disorders of the central nervous system.

Auditory Processing Deficits Following Sport-Related or Motor Vehicle Accident Injuries

This brief clinical study was designed to investigate further the possible link between traumatic brain injury (TBI) and/or whiplash injury (WI) with acquired auditory processing disorder (APD). Other studies have shown long standing effects of TBI and WI, and a study by Turgeon et al., examined the link between sport-induced concussion and APD. Four participants ages 18 to 30 years of age who self-reported a history of sport-related or motor vehicle accident head injuries participated in the following procedures: case history, behavioral testing, electrophysiological testing including auditory brainstem responses (ABR) and middle latency responses (MLR), and self-report questionnaires of post head and/or whiplash injury symptoms. The results of the testing were individually analyzed to see if results were consistent with a diagnosis of APD, or some evidence of a non-sensory deficit to the auditory system. The overall results of this study were also compared with the results of Turgeon et al., study. The results of the study shows that electrophysiological testing may be outside of normal limits even when behavioral testing does not support an APD diagnosis. Furthermore, the degree of reported symptoms and difficulties in the participants’ case history does not always carry over to the behavioral and electrophysiological testing results.

Functional dissociation between regularity encoding and deviance detection along the auditory hierarchy.

Auditory deviance detection based on regularity encoding appears as one of the basic functional properties of the auditory system. It has traditionally been assessed with the mismatch negativity (MMN) long-latency component of the auditory evoked potential (AEP). Recent studies have found earlier correlates of deviance detection based on regularity encoding. They occur in humans in the first 50ms after sound onset, at the level of the middle-latency response of the AEP, and parallel findings of stimulus-specific adaptation observed in animal studies. However, the functional relationship between these different levels of regularity encoding and deviance detection along the auditory hierarchy has not yet been clarified. Here we addressed this issue by examining deviant-related responses at different levels of the auditory hierarchy to stimulus changes varying in their degree of deviation regarding the spatial location of a repeated standard stimulus. Auditory stimuli were presented randomly from five loudspeakers at azimuthal angles of 0°, 12°, 24°, 36° and 48° during oddball and reversed-oddball conditions. Middle-latency responses and MMN were measured. Our results revealed that middle-latency responses were sensitive to deviance but not the degree of deviation, whereas the MMN amplitude increased as a function of deviance magnitude. These findings indicated that acoustic regularity can be encoded at the level of the middle-latency response but that it takes a higher step in the auditory hierarchy for deviance magnitude to be encoded, thus providing a functional dissociation between regularity encoding and deviance detection along the auditory hierarchy.

Early indices of deviance detection in humans and animal models

Detecting unexpected stimuli in the environment is a critical function of the auditory system. Responses to unexpected “deviant” sounds are enhanced compared to responses to expected stimuli. At the human scalp, deviance detection is reflected in the mismatch negativity (MMN) and in an enhancement of the middle-latency response (MLR). Single neurons often respond more strongly to a stimulus when rare than when common, a phenomenon termed stimulus-specific adaptation (SSA). Here we compare stimulus-specific adaptation with scalp-recorded deviance-related responses. We conclude that early markers of deviance detection in the time range of the MLR could be a direct correlate of cortical SSA. Both occur at an early level of cortical activation, both are robust findings with low-probability stimuli, and both show properties of genuine deviance detection. Their causal relation with the later scalp-recorded MMN is a key question in this field.

Potencial Evocado Auditivo de Média Latência (PEAML) em crianças e adolescentes brasileiros: revisão sistemática

RESUMO Objetivo: Revisar sistematicamente a literatura científica sobre a realização do Potencial Evocado Auditivo de Média Latência (PEAML) em crianças e adolescentes brasileiros. Estratégia de pesquisa: Foram pesquisados artigos publicados a partir de 2009, em português, inglês ou espanhol, nas bases de dados eletrônicas MEDLINE, SciELO, BIREME e LILACS. Os artigos selecionados envolveram a realização do PEAML em crianças e/ou adolescentes brasileiros. Após triagem, os artigos foram analisados segundo a iniciativa “Strengthening the Reporting of Observational Studies in Epidemiology” (STROBE). Critérios de seleção: Foram excluídos artigos repetidos nas bases de busca e também os relatos de caso. Resultados: A busca inicial identificou 1315 artigos, dos quais oito foram selecionados para compor a revisão. Verificou-se predomínio de estudos observacionais transversais (75%); estimulação tipo click (100%), com velocidade até 11/s (100%) e intensidade de 70 dBNA (88%); uso de filtro passa-alta de 10 Hz (50%) e passa-baixa de 200 Hz (75%); montagem dos eletrodos em C3/C4 (ativos) A1/A2 (referências), e Fpz (neutro) (88%); amplitude Na-Pa, como principal parâmetro de comparação e normalidade; e uso do teste ANOVA (63%) para análise estatística. Nos estudos revisados, a média da latência da onda Pa e da amplitude Na-Pa em crianças e adolescentes normo-ouvintes foi de 32 milissegundos e 1,57 microvolts, respectivamente. Conclusão: Não há consenso quanto aos parâmetros de registro do PEAML em crianças e adolescentes brasileiros. Ainda assim, a média de latência de Pa e amplitude Na-Pa encontrada em crianças e adolescentes brasileiros normo-ouvintes, avaliados nos oito artigos desta revisão, concorda com os parâmetros de normalidade já estabelecidos internacionalmente.

EEG Recorded from the Ear: Characterizing the Ear-EEG Method.

Highlights Auditory middle and late latency responses can be recorded reliably from ear-EEG.For sources close to the ear, ear-EEG has the same signal-to-noise-ratio as scalp.Ear-EEG is an excellent match for power spectrum-based analysis.A method for measuring electroencephalograms (EEG) from the outer ear, so-called ear-EEG, has recently been proposed. The method could potentially enable robust recording of EEG in natural environments. The objective of this study was to substantiate the ear-EEG method by using a larger population of subjects and several paradigms. For rigor, we considered simultaneous scalp and ear-EEG recordings with common reference. More precisely, 32 conventional scalp electrodes and 12 ear electrodes allowed a thorough comparison between conventional and ear electrodes, testing several different placements of references. The paradigms probed auditory onset response, mismatch negativity, auditory steady-state response and alpha power attenuation. By comparing event related potential (ERP) waveforms from the mismatch response paradigm, the signal measured from the ear electrodes was found to reflect the same cortical activity as that from nearby scalp electrodes. It was also found that referencing the ear-EEG electrodes to another within-ear electrode affects the time-domain recorded waveform (relative to scalp recordings), but not the timing of individual components. It was furthermore found that auditory steady-state responses and alpha-band modulation were measured reliably with the ear-EEG modality. Finally, our findings showed that the auditory mismatch response was difficult to monitor with the ear-EEG. We conclude that ear-EEG yields similar performance as conventional EEG for spectrogram-based analysis, similar timing of ERP components, and equal signal strength for sources close to the ear. Ear-EEG can reliably measure activity from regions of the cortex which are located close to the ears, especially in paradigms employing frequency-domain analyses.

Effects of rate (0.3–40/s) on simultaneously recorded auditory brainstem, middle and late responses using deconvolution

ObjectiveAuditory evoked potentials (AEPs) are typically acquired in either transient (low-rate) or steady state (high-rate) conditions. This study utilizes deconvolution to obtain transient responses over a range of rates from 0.3 to 40/s, to establish a rate profile of transient responses employing uniform recording conditions. MethodsDeconvolution is used to obtain transient responses from quasi steady state recordings for rates 3.5–40/s, and components are scored and waveform morphologies are compared across rates. ResultsAll component latencies remain stable across all rates other than P2, which decreases for rates up to 3.5/s. Amplitudes for brainstem (V, Na), middle latency (Pa, Nb), and late (Pb/P1, N1 and P2) responses increased for rates below 1, 2 and 3.5/s, respectively. Rates between 3.5 and 25/s undergo a gradual morphology transition, above which oscillations begin to occur after 100ms. ConclusionsAuditory brainstem, middle and late latency components other than P2 show stable latencies across 0.3–40/s with varying amplitude rate dependencies. SignificanceObtaining a transient response rate profile utilizing uniform acquisition parameters is useful for an improved understanding of how individual AEP components interact with stimulation rate, and can provide a more comprehensive assessment of the ascending auditory pathway and primary auditory cortices.

Comparison of Auditory Middle-Latency Responses From Two Deconvolution Methods at 40 Hz

Auditory middle-latency responses (MLRs) are reported to be particularly susceptible to stimulation rate. Deconvolution methods are necessary to unwrap the overlapping responses at a high rate under the linear superposition assumption. This study aims to investigate and compare the MLR characteristics at high and conventional stimulation rates. The characteristics were examined in healthy adults by using two closely related deconvolution paradigms, namely continuous-loop averaging deconvolution and multirate steady-state averaging deconvolution at a mean rate of 40Hz, and a conventional low rate of 5Hz. The morphology and stability of the MLRs can benefit from a high-rate stimulation. It appears that stimulation sequencing strategies of deconvolution methods exerted divergent rate effects on MLR characteristics, which might be associated with different adaptation mechanisms. MLRs obtained by two deconvolution methods and the conventional reference feature differently from one another. These findings have critical implications in our current understanding of the rate effects on MLR characteristics which may inspire further studies to explore the characteristics of evoked responses at high rates and deconvolution paradigms.

Deviance-Related Responses along the Auditory Hierarchy: Combined FFR, MLR and MMN Evidence.

The mismatch negativity (MMN) provides a correlate of automatic auditory discrimination in human auditory cortex that is elicited in response to violation of any acoustic regularity. Recently, deviance-related responses were found at much earlier cortical processing stages as reflected by the middle latency response (MLR) of the auditory evoked potential, and even at the level of the auditory brainstem as reflected by the frequency following response (FFR). However, no study has reported deviance-related responses in the FFR, MLR and long latency response (LLR) concurrently in a single recording protocol. Amplitude-modulated (AM) sounds were presented to healthy human participants in a frequency oddball paradigm to investigate deviance-related responses along the auditory hierarchy in the ranges of FFR, MLR and LLR. AM frequency deviants modulated the FFR, the Na and Nb components of the MLR, and the LLR eliciting the MMN. These findings demonstrate that it is possible to elicit deviance-related responses at three different levels (FFR, MLR and LLR) in one single recording protocol, highlight the involvement of the whole auditory hierarchy in deviance detection and have implications for cognitive and clinical auditory neuroscience. Moreover, the present protocol provides a new research tool into clinical neuroscience so that the functional integrity of the auditory novelty system can now be tested as a whole in a range of clinical populations where the MMN was previously shown to be defective.

CHARAKTERYSTYKA INTERFERENCJI POCHODZĄCYCH Z ARTEFAKTÓW MIĘŚNIOWYCH W SYGNAŁACH SŁUCHOWYCH POTENCJAŁÓW WYWOŁANYCH

BackgroundIt is well known that muscle artifacts negatively affect auditory evoked potential (AEP) recordings. However, the precise relation between the set of muscles involved and the specific AEP affected is not clear. Most audiologists believe that increase in the tension of any muscle in the body would affect all AEPs to the same extent, while some believe that only head and neck muscles affect AEPs. Logically, this relation will depend on the frequency characteristics of the muscle artifact. However, to the best of our knowledge, there is no scientific documentation of the extent of interference created by various muscle responses on auditory brainstem responses (ABRs), middle latency responses (MLRs), and late latency responses (LLRs). The present study therefore sought to analyse the minimum artifact rejection threshold required for ABR, MLR, and LLR under various artifact-inducing conditions.Material and MethodsThe present study involved 40 individuals of age 17 to 24 years. For each participant, the effects of muscle artifacts on three popular, clinically relevant AEPs (ABR, MLR, and LLR) were determined. First, recording was done in a rest condition where participants were seated in a reclining chair and asked to close their eyes and maintain a relaxed position. Then the participants were asked to carry out one of the following tasks: blink their eyes continuously; spread their lips; or stiffen their neck, hand, or leg muscles maximally. While tensing each of these set of muscles, the minimum artifact rejection threshold (MART) was noted.ResultsThe results showed that each of the artifact-inducing conditions affected the three target AEPs differently. At rest, there was no significant difference in MART across the three AEPs, but artifact-inducing conditions produced different effects.ConclusionsNot all artifacts affect every AEP equally. For good AEP recordings one needs to have a clear understanding of various muscle potentials and their relative effect on each AEP.

Middle latency response testing for auditory cognition in canines

Middle latency response testing for auditory cognition in canines

Audiological and Electrophysiological Changes in Patients with Vitiligo.

The study was conducted to evaluate the audiological and electrophysiological findings in patients with Vitiligo and to compare the findings with otologically and audiologically normal controls. Study group included 50 subjects (25 Males, 25 Females) with Vitiligo (Mean age-27.4years) and control group contained 40 age-matched normal hearing subjects. Pure tone audiometry (PTA) with extended high frequency audiometry, Otoacoustic emissions (OAEs), Tympanometry, Auditory brainstem responses (ABR) and Middle latency responses (MLR) were conducted in all subjects. Comparison of the study group with the control group showed statistically significant differences (p<0.05) on PTA, in Transient otoacoustic emissions (TOAEs) at 1, 2, 3, 4kHz and in distortion product otoacoustic emissions (DPOAEs) at 357, 499, 704, 1003Hz. On ABR, statistically significant differences were observed between the groups in wave I (p<0.01) in both ears, wave V (p<0.05) in left ear and on interpeak latency of I-III (p<0.01, p<0.05), III-V (p<0.01 in left ear) and I-V (p<0.01, p<0.05) in left and right ears respectively. When patients with localized vitiligo were compared with generalized vitiligo, the SNR of TOAEs was highly significant in both ears at 2KHz (p<0.05), 3kHz (p<0.01) and 4kHz (p<0.05). PTA average of 2 KHz, 4 and 8kHz (PTA2) showed a significant difference (p<0.01) when localized vitiligo was compared to generalized vitiligo. Results support possible auditory and electrophysiological changes in Vitiligo patients along with decreased cochlear function.

Auditory Middle Latency Response and Phonological Awareness in Students with Learning Disabilities.

Introduction Behavioral tests of auditory processing have been applied in schools and highlight the association between phonological awareness abilities and auditory processing, confirming that low performance on phonological awareness tests may be due to low performance on auditory processing tests. Objective To characterize the auditory middle latency response and the phonological awareness tests and to investigate correlations between responses in a group of children with learning disorders. Methods The study included 25 students with learning disabilities. Phonological awareness and auditory middle latency response were tested with electrodes placed on the left and right hemispheres. The correlation between the measurements was performed using the Spearman rank correlation coefficient. Results There is some correlation between the tests, especially between the Pa component and syllabic awareness, where moderate negative correlation is observed. Conclusion In this study, when phonological awareness subtests were performed, specifically phonemic awareness, the students showed a low score for the age group, although for the objective examination, prolonged Pa latency in the contralateral via was observed. Negative weak to moderate correlation for Pa wave latency was observed, as was positive weak correlation for Na-Pa amplitude.

Middle latency response correlates of single and double deviant stimuli in a multi-feature paradigm

ObjectiveThis study aimed to test single and double deviance-related modulations of the middle latency response (MLR) and the applicability of the optimum-2 multi-feature paradigm. MethodsThe MLR and the MMN to frequency, intensity and double-feature deviants of an optimum-2 multi-feature paradigm and the MMN to double-feature deviants of an oddball paradigm were recorded in young adults. ResultsDouble deviants elicited significant enhancements of the Nb and Pb MLR waves compared with the waves elicited by standard stimuli. These enhancements equalled approximately the sum of the numerical amplitude differences elicited by the single deviants. In contrast, the MMN to double deviants did not show such additivity. MMNs elicited by double deviants of the multi-feature and the oddball paradigm showed no significant difference in amplitude or latency. ConclusionsThe optimum-2 multi-feature paradigm is suitable for recording double deviance-related modulations of the MLR. Interspersed intensity and frequency deviants in the standard trace of the optimum-2 condition multi-feature paradigm did not weaken the double MMN. SignificanceThe optimum-2 multi-feature paradigm could be especially beneficial for clinical studies on early deviance-related modulations in the MLR, due to its optimized utilization of the recording time.

Spatial auditory regularity encoding and prediction: Human middle-latency and long-latency auditory evoked potentials

By encoding acoustic regularities present in the environment, the human brain can generate predictions of what is likely to occur next. Recent studies suggest that deviations from encoded regularities are detected within 10–50ms after stimulus onset, as indicated by electrophysiological effects in the middle latency response (MLR) range. This is upstream of previously known long-latency (LLR) signatures of deviance detection such as the mismatch negativity (MMN) component. In the present study, we created predictable and unpredictable contexts to investigate MLR and LLR signatures of the encoding of spatial auditory regularities and the generation of predictions from these regularities. Chirps were monaurally delivered in an either regular (predictable: left–right–left–right) or a random (unpredictable left/right alternation or repetition) manner. Occasional stimulus omissions occurred in both types of sequences. Results showed that the Na component (peaking at 34ms after stimulus onset) was attenuated for regular relative to random chirps, albeit no differences were observed for stimulus omission responses in the same latency range. In the LLR range, larger chirp-and omission-evoked responses were elicited for the regular than for the random condition, and predictability effects were more prominent over the right hemisphere. We discuss our findings in the framework of a hierarchical organization of spatial regularity encoding.This article is part of a Special Issue entitled SI: Prediction and Attention.

Individual Differences in Behavioral and Electrophysiological Measures of Binaural Processing Across the Adult Life Span.

The purpose of the present study was to examine individual differences in binaural processing across the adult life span. Sixty listeners (aged 23-80 years) with symmetrical hearing were tested. Binaural behavioral processing was measured by the Words-in-Noise Test, the 500-Hz masking level difference, and the Dichotic Digit Test. Electrophysiologic responses were assessed by the auditory middle latency response binaural interaction component. No correlations among binaural measures were found. Age accounted for the greatest amount of variability in speech-in-noise performance. Age was significantly correlated with the Words-in-Noise Test binaural advantage and dichotic ear advantage. Partial correlations, however, revealed that this was an effect of hearing status rather than age per se. Inspection of individual results revealed that 20% of listeners demonstrated reduced binaural performance for at least 2 of the binaural measures. The lack of significant correlations among variables suggests that each is an important measurement of binaural abilities. For some listeners, binaural processing was abnormal, reflecting a binaural processing deficit not identified by monaural audiologic tests. The inclusion of a binaural test battery in the audiologic evaluation is supported given that these listeners may benefit from alternative forms of audiologic rehabilitation.

迷走神経刺激がラット聴皮質における順応反応に及ぼす影響

Vagus nerve stimulation (VNS) causes neuromodulatory effects in the cerebral cortex, which are useful not only for therapy on intractable epilepsy but also for enhancement of higher brain functions such as cognition and memory. Recently, it has been reported that VNS may also affect auditory-evoked neural activities. However, it remains to be elucidated how and where VNS modulates neural activities in the auditory cortex. Here we examined effects of VNS on adaptation of neural activities in response to repeated stimuli in the rat auditory cortex. Both a surface and depth microelectrode array recorded auditory evoked potentials in response to click trains and oddball stimuli. We quantified a repetition rate transfer function (RRTF) and common stimulus-specific adaptation (SSA) index (CSI) from the amplitude of middle-latency response (P1). Consequently, VNS affected temporal response property and increased SSA in the layer 1 and 5/6 of auditory cortex. This result suggests that VNS strengthens adaptation in the auditory cortex in a layer-specific manner.

Auditory brainstem and middle latency responses recorded at fast rates with randomized stimulation.

Randomized stimulation and averaging (RSA) allows auditory evoked potentials (AEPs) to be recorded at high stimulation rates. This method does not perform deconvolution and must therefore deal with interference derived from overlapping transient evoked responses. This paper analyzes the effects of this interference on auditory brainstem responses (ABRs) and middle latency responses (MLRs) recorded at rates of up to 300 and 125 Hz, respectively, with randomized stimulation sequences of a jitter both greater and shorter than the dominant period of the ABR/MLR components. Additionally, this paper presents an advanced approach for RSA [iterative-randomized stimulation and averaging (I-RSA)], which includes the removal of the interference associated with overlapping responses through an iterative process in the time domain. Experimental results show that (a) RSA can be efficiently used in the recording of AEPs when the jitter of the stimulation sequence is greater than the dominant period of the AEP components, and (b) I-RSA maintains all the advantages of RSA and is not constrained by the restriction of a minimum jitter. The significance of the results of this study is discussed.

Auditory processing deficit in a patient with Ramsay Hunt syndrome

Objective: The present study was undertaken to investigate the auditory processing skills in an individual diagnosed as ‘herpes zoster oticus with polycranialis multiplexa involving VII, IX and X cranial nerve with lacunar infarct in the right frontal cortex’ (Ramsay Hunt syndrome type II). Prior investigation on hearing sensitivity revealed that sensorineural hearing loss with both cochlear and retrocochlear involvement was frequent in these individuals. Apart from hearing loss, multiple neurological conditions such as infections, myelopathies and vasculopathies relating to both central and peripheral nervous system, were also found to be associated with this condition. Research evidence suggested that an auditory processing disorder may be associated with all these conditions. It is, therefore, possible that auditory processing disorders may be associated with Ramsay Hunt syndrome type II. There is a dearth of literature investigating auditory processing skills in such individuals, which suggested the need to investigate such skills. Study design: This was a single case study design investigating auditory processing skills using a series of behavioural and objective tests known to be sensitive enough to assess them. Behavioural tests such as speech perception in noise, gap detection, duration pattern and duration discrimination and objective tests like speech-evoked auditory brainstem responses, click-evoked auditory middle latency responses and speech-evoked auditory middle latency responses were performed. Results: Investigations of the peripheral auditory system revealed a mild sensorineural hearing loss in the right ear and minimal hearing loss in the left ear with no indication of retrocochlear pathology. Poor scores on speech perception in noise, gap detection, duration pattern and a duration discrimination test pointed towards the presence of auditory processing disorder. These results were further confirmed using more objective tests where the absence of a far-field response component in the speech-evoked auditory brainstem response, as well as absence of the middle latency response, strengthened the behavioural test findings. Conclusions: The results of the present case study focus on the presence of auditory processing disorders and, thus, meticulous investigations of auditory processing skills are warranted in the audiological test battery of these individuals.

Auditory Middle Latency Responses: Different Register Derivations

Introduction: The auditory middle latency responses are bioelectrical answers to the auditive neurofunctional evaluation in patients with central auditive nervous system injuries and dysfunctions. Therefore, two active register canals were used to set electrodes in the right and left hemispheres and, when the right and left ears are stimulated, there are counter lateral and ipsilateral registers. It is not clear in the literature, which electrodes disposition gives the better answer.