Auditory Event-related Potential Responses Research Articles

Auditory event-related potentials index faster processing of natural speech but not synthetic speech over nonspeech analogs in children

Given the crucial role of speech sounds in human language, it may be beneficial for speech to be supported by more efficient auditory and attentional neural processing mechanisms compared to nonspeech sounds. However, previous event-related potential (ERP) studies have found either no differences or slower auditory processing of speech than nonspeech, as well as inconsistent attentional processing. We hypothesized that this may be due to the use of synthetic stimuli in past experiments. The present study measured ERP responses during passive listening to both synthetic and natural speech and complexity-matched nonspeech analog sounds in 22 8–11-year-old children. We found that although children were more likely to show immature auditory ERP responses to the more complex natural stimuli, ERP latencies were significantly faster to natural speech compared to cow vocalizations, but were significantly slower to synthetic speech compared to tones. The attentional results indicated a P3a orienting response only to the cow sound, and we discuss potential methodological reasons for this. We conclude that our results support more efficient auditory processing of natural speech sounds in children, though more research with a wider array of stimuli will be necessary to confirm these results. Our results also highlight the importance of using natural stimuli in research investigating the neurobiology of language.

Maternal sleep quality during pregnancy is associated with neonatal auditory ERPs

Poor maternal sleep quality during pregnancy may act as a prenatal stress factor for the fetus and associate with neonate neurocognition, for example via fetal programming. The impacts of worsened maternal sleep on neonatal development and, more specifically on neonatal auditory brain responses, have not been studied. A total of 155 mother-neonate dyads drawn from the FinnBrain Birth Cohort Study participated in our study including maternal self-report questionnaires on sleep at gestational week 24 and an event-related potential (ERP) measurement among 1-2-day-old neonates. For sleep quality assessment, the Basic Nordic Sleep Questionnaire (BNSQ) was used and calculated scores for (1) insomnia, (2) subjective sleep loss and (3) sleepiness were formed and applied in the analyses. In the auditory ERP protocol, three emotionally uttered pseudo words (in happy, angry and sad valence) were presented among neutrally uttered pseudo words. To study the relations between prenatal maternal sleep quality and auditory emotion-related ERP responses, mixed-effects regression models were computed for early (100–200 ms) and late (300–500 ms) ERP response time-windows. All of the selected BNSQ scores were associated with neonatal ERP responses for happy and angry emotion stimuli (sleep loss and sleepiness in the early, and insomnia, sleep loss and sleepiness in the late time-window). For sad stimuli, only maternal sleep loss predicted the neonatal ERP response in the late time-window, likely because the overall ERP was weakest in the sad condition. We conclude that maternal sleep quality during pregnancy is associated with changes in neonatal auditory ERP responses.

Social-emotional processing in nonverbal individuals with Angelman syndrome: evidence from brain responses to known and novel names.

The combination of intellectual, communicative and motor deficits limits the use of standardised behavioural assessments in individuals with Angelman syndrome (AS). The current study aimed to objectively evaluate the extent of social-emotional processing in AS using auditory event-related potentials (ERPs) during passive exposure to spoken stimuli. Auditory ERP responses were recorded in 13 nonverbal individuals with the deletion subtype of AS, age 4-45years, during the name recognition paradigm, in which their own names and names of close others (relative or friend) were presented among novel names. No behavioural responses were required. Contrary to findings in typical children and adults, there was no significant evidence of differential neural response to known vs. novel names in participants with AS. Nevertheless, greater amplitude differences between known and unknown names demonstrated the predicted association with better interpersonal relationships and receptive communication abilities. These findings indicate good tolerability of ERP procedures (85% success rate). The lack of own name differentiation is consistent with increased incidence of the autism-related symptoms in AS. Strong associations between the caregiver reports of adaptive functioning and neural indices of known name recognition support the utility of brain-based measures for objectively evaluating cognitive and affective processes in nonverbal persons with neurodevelopmental disorders.

Auditory sensitivity exhibits sexual dimorphism and seasonal plasticity in music frogs.

Seasonal changes in the structure and function of the vertebrate brain have been described in many species, particularly in seasonal breeders. However, it remains unclear whether sexual dimorphism varies between breeding seasons for specific brain regions. Auditory event-related potential (ERP) changes were evaluated in the Emei music frog (Babina daunchina) to assess sexual dimorphism and seasonal variations in auditory sensitivity. An acoustic playback experiment using an oddball paradigm design was conducted, in which two conspecific call types were used as deviant stimuli with synthesized white noise as standard stimulus. ERP components were analyzed for the telencephalon and mesencephalon of both sexes in the non-reproductive and reproductive states. Results show that auditory sensitivity is modulated by reproductive status, implying that seasonal plasticity is involved in auditory perception. Moreover, the amplitude of the N1 ERP component (mean amplitudes during the interval occurring 30-130ms after stimulus onset) is higher in females for the telencephalon and higher in males for the mesencephalon, regardless of reproductive status and acoustic stimulus type. These results show that auditory ERP responses for specific brain regions exhibit sexual dimorphism in the absence of exogenous sexual stimulation during both the two reproductive states in the music frog.

Differential effects of hearing impairment and age on electrophysiological and behavioral measures of speech in noise

Understanding speech in background noise is difficult for many listeners with and without hearing impairment (HI). This study investigated the effects of HI on speech discrimination and recognition measures as well as speech-evoked cortical N1-P2 and MMN auditory event-related potentials (AERPs) in background noise. We aimed to determine which AERP components can predict the effects of HI on speech perception in noise across adult listeners with and without HI. The data were collected from 18 participants with hearing thresholds ranging from within normal limits to bilateral moderate-to-severe sensorineural hearing loss. Linear mixed effects models were employed to examine how hearing impairment, age, stimulus type, and SNR listening condition affected neural and behavioral responses and what AERP components were correlated with effects of HI on speech-in-noise perception across participants. Significant effects of age were found on the N1-P2 but not on MMN, and significant effects of HI were observed on the MMN and behavioral measures. The results suggest that neural responses reflecting later cognitive processing of stimulus discrimination may be more susceptible to the effects of HI on the processing of speech in noise than earlier components that signal the sensory encoding of acoustic stimulus features. Objective AERP responses were also potential neural predictors of speech perception in noise across participants with and without HI, which has implications for the use of AERPs as a potential clinical tool for assessing speech perception in noise.

Audio-visual speech perception: a developmental ERP investigation.

Being able to see a talking face confers a considerable advantage for speech perception in adulthood. However, behavioural data currently suggest that children fail to make full use of these available visual speech cues until age 8 or 9. This is particularly surprising given the potential utility of multiple informational cues during language learning. We therefore explored this at the neural level. The event-related potential (ERP) technique has been used to assess the mechanisms of audio-visual speech perception in adults, with visual cues reliably modulating auditory ERP responses to speech. Previous work has shown congruence-dependent shortening of auditory N1/P2 latency and congruence-independent attenuation of amplitude in the presence of auditory and visual speech signals, compared to auditory alone. The aim of this study was to chart the development of these well-established modulatory effects over mid-to-late childhood. Experiment 1 employed an adult sample to validate a child-friendly stimulus set and paradigm by replicating previously observed effects of N1/P2 amplitude and latency modulation by visual speech cues; it also revealed greater attenuation of component amplitude given incongruent audio-visual stimuli, pointing to a new interpretation of the amplitude modulation effect. Experiment 2 used the same paradigm to map cross-sectional developmental change in these ERP responses between 6 and 11 years of age. The effect of amplitude modulation by visual cues emerged over development, while the effect of latency modulation was stable over the child sample. These data suggest that auditory ERP modulation by visual speech represents separable underlying cognitive processes, some of which show earlier maturation than others over the course of development.

Improved detection of amnestic MCI by means of discriminative vector quantization of single-trial cognitive ERP responses

Cognitive event-related potentials (ERPs) are widely employed in the study of dementive disorders. The morphology of averaged response is known to be under the influence of neurodegenerative processes and exploited for diagnostic purposes. This work is built over the idea that there is additional information in the dynamics of single-trial responses.We introduce a novel way to detect mild cognitive impairment (MCI) from the recordings of auditory ERP responses. Using single trial responses from a cohort of 25 amnestic MCI patients and a group of age-matched controls, we suggest a descriptor capable of encapsulating single-trial (ST) response dynamics for the benefit of early diagnosis.A customized vector quantization (VQ) scheme is first employed to summarize the overall set of ST-responses by means of a small-sized codebook of brain waves that is semantically organized. Each ST-response is then treated as a trajectory that can be encoded as a sequence of code vectors. A subject's set of responses is consequently represented as a histogram of activated code vectors. Discriminating MCI patients from healthy controls is based on the deduced response profiles and carried out by means of a standard machine learning procedure.The novel response representation was found to improve significantly MCI detection with respect to the standard alternative representation obtained via ensemble averaging (13% in terms of sensitivity and 6% in terms of specificity). Hence, the role of cognitive ERPs as biomarker for MCI can be enhanced by adopting the delicate description of our VQ scheme.

Auditory evoked potentials remain abnormal after CPAP treatment in patients with severe obstructive sleep apnoea

Objective To assess the effects of 3 months of optimal CPAP treatment on auditory event related potentials (AERP) in patients with severe obstructive sleep apnoea (OSA) compared with healthy controls. Methods Auditory odd-ball related N1, P2, N2 and P3 AERP components were assessed in 9 severe OSA subjects and 9 healthy controls at baseline evaluation and at ∼3 months follow-up in both groups, with OSA subjects treated with continuous positive air-way pressure (CPAP) during this period. Results Severe OSA subjects showed significantly delayed, P2, N2 and P3 latencies, and significantly different P2 and P3 amplitudes compared to controls at baseline (group effect, all p < 0.05). At follow-up evaluation P3 latency shortened in treated OSA patients but remained prolonged compared to controls (group by treatment interaction, p < 0.05) despite high CPAP compliance (6 h/night). The earlier AERP (P2 and N2) components did not change in either controls or OSA patients at follow-up and remained different in patients versus controls. Conclusions This study demonstrates that in severe OSA patients AERP responses show minimal or no improvement and remain abnormal following 3 months of optimal CPAP treatment. Significance Persistent cortical sensory processing abnormalities despite treatment in severe OSA may have implications for daytime neurobehavioral performance and safety in OSA patients. AERP responses may help identify residual performance deficits and risks.

Cortical auditory processing in preterm newborns: An ERP study

The aim of this study was to investigate the effects of gestational age on the auditory event-related potentials (AERPs) in preterm newborns of extremely low (23–29 weeks, N = 20) and low gestational age (30–34 weeks, N = 19). All subjects were tested at the same post-conceptional age of 35 weeks. An auditory oddball paradigm was used with frequently occurring “standard” tones at 1000 Hz and rarely occurring “deviant” tones at 2000 Hz. Newborns of less than 30 gestational weeks showed smaller AERPs responses (P1i, N2i and mismatch response) than the older ones. Our results suggest the role of gestational age as the main factor explaining cortical functioning at this early age.

Differences in AERP responses and atypical hemispheric specialization in 17-month-old children at risk of dyslexia

To determine the auditory event-related potential (AERP) correlates of phoneme perception in 17-month-old children at risk of dyslexia and controls, AERPs were elicited by standard (/bAk/) and deviant (/dAk/) word stimuli presented in an oddball paradigm. The at-risk children tended to show delayed P1 and P2 peaks for standard stimuli. Hemispheric group differences were observed for N2 amplitude and P1 latency, suggesting atypical processing of spoken words in at-risk children. Larger P2 and to a lesser extent P1 amplitudes following deviant words occurred in the control but not in the at-risk group, this may signal poorer phoneme discrimination in at-risk children. The present AERP results offer clues to where to look for a marker to identify children at high risk of reading and writing problems at an early age to facilitate early intervention.

Event-related brain potentials differentiate normal and disabled readers

Auditory event-related potentials (AERPs) recorded to irrelevant tone pairs while subjects performed visual, reading-related cognitive tasks differed significantly between normal and disabled readers. Disabled readers as compared with normal readers showed significantly lower amplitude right hemisphere AERP responses during tasks that involved visual-phonemic transfer of information and simple pattern recognition. Disabled readers as compared with normal readers also showed significantly higher amplitude left hemisphere responses during the visual-phonemic task. In both experimental conditions the reading-disabled subjects showed significantly lower amplitude right than left hemisphere AERP responses. Task-related strategies did not differ between groups. The pattern of AERP amplitude asymmetry found for disabled readers, which was opposite to that found for normal readers, suggests that the same reading-related tasks activated different cerebral processes in the two groups studied.