Tone Stimuli Research Articles

Audiological Characteristics of a Sample of Adults With Misophonia.

The aim of this study was to describe the audiological test results from a sample of 60 adults with self-reported misophonia. Audiological testing was completed prior to participant randomization in a controlled trial for misophonia treatment. Participants completed the Inventory of Hyperacusis Symptoms Survey (IHS), the Tinnitus and Hearing Survey (THS), the Misophonia Questionnaire (MQ), and behavioral and objective audiometric measures. Hearing thresholds were less than 25 dBHL for 97% of the participants. Loudness discomfort levels for tonal stimuli suggested hyperacusis in 25% of the sample. Total scores on the IHS indicated that 12% met the clinical cutoff for hyperacusis, and, on the THS, 27% experienced problems with tinnitus, 77% experienced problems with hearing, and 53% experienced problems with sound tolerance. On the MQ, 37% indicated mild levels of misophonia and 58% indicated moderate levels. For speech-in-noise testing, a mild signal-to-noise ratio loss was present for 15% of participants. Most of the participants had present distortion product otoacoustic emissions (DPOAEs). Audiological data on individuals with misophonia are lacking. In this article, we present results from audiological testing on 60 adults with self-reported misophonia. Most had normal peripheral hearing sensitivity based on pure-tone audiometry and DPOAE measures; some had difficulties with sound sensitivities and understanding speech-in-noise, self-report indicated problems with hyperacusis, tinnitus, and hearing difficulty.

Auditory distraction, time perception, and the role of age: ERP evidence from a large cohort study

Cognitive aging is typically associated with a higher susceptibility to distraction by concurrent, but task-irrelevant stimuli. Here, we studied the cognitive sub-processes involved in a sample of 484 healthy adults aged 20–70 years from the Dortmund Vital Study (Clinicaltrials.gov NCT05155397). Participants judged the duration of tone stimuli of a random sequence of long and short tones, having either a regular (standard) pitch or rare (deviant) pitch. Deviance-related ERPs were explored, reflecting neuro-cognitive correlates of pre-attentive deviance detection (MMN), attention allocation toward (P3a) and processing of (P3b) the deviance, and re-orienting toward the task-relevant stimulus feature (RON). Accuracy was reduced for deviant long tones, possibly due to withdrawing attention from processing the time information, making long stimuli appear shorter. This effect increased with age, and cluster-based permutation tests on the correlation of ERPs and age as well as linear mixed modeling indicated a decrease in MMN, an increase in P3a with long tones, and decreases in P3b and RON. This suggests a greater attentional orienting to the deviant stimulus feature and a reduced re-orienting to the task-relevant feature with increasing age.

Contributions of associative and non-associative learning to the dynamics of defensive ethograms.

Defensive behavior changes based on threat intensity, proximity, and context of exposure, and learning about danger-predicting stimuli is critical for survival. However, most Pavlovian fear conditioning paradigms focus only on freezing behavior, obscuring the contributions of associative and non-associative mechanisms to dynamic defensive responses. To thoroughly investigate defensive ethograms, we subjected male and female adult C57BL/6J mice to a Pavlovian conditioning paradigm that paired footshock with a serial compound stimulus (SCS) consisting of distinct tone and white noise (WN) stimulus periods. To investigate how associative and non-associative mechanisms affect defensive responses, we compared this paired SCS-footshock group with four control groups that were conditioned with either pseudorandom unpaired presentations of SCS and footshock, shock only, or reversed SCS presentations with inverted tone--WN order, with paired or unpaired presentations. On day 2 of conditioning, the paired group exhibited robust freezing during the tone period with switching to explosive jumping and darting behaviors during the WN period. Comparatively, the unpaired and both reverse SCS groups expressed less tone-induced freezing and rarely showed jumping or darting during WN. Following the second day of conditioning, we observed how defensive behavior changed over two extinction sessions. During extinction, the tone-induced freezing decreased in the paired group and mice rapidly shifted from escape jumping during WN to a combination of freezing and darting. The unpaired, unpaired reverse, and shock-only groups displayed defensive tail rattling and darting during the SCS, with minimal freezing and jumping. Interestingly, the paired reverse group did not jump to WN, and tone-evoked freezing was resistant to extinction. These findings demonstrate that non-associative factors promote some defensive responsiveness, but associative factors are required for robust cue-induced freezing and high-intensity flight expression.

Comparison of probe tone and click stimulus at 226 Hz frequency on acoustic ımmittance measurement in normal hearing adults: a cross-sectional study

ObjectivesAcoustic immittancemetry measurement is made using a probe tone or click stimulus at a frequency of 226 Hz, which is included in the audiological test battery. This study aims to compare tympanometric peak pressure (TPP), static acoustic admittance (Ytm), equivalent external ear canal volume (Vea) and tympanometric width (TW) values measured with probe tone and click stimulus at 226 Hz frequency.DesignMeasurements were made with a probe tone and click stimulus at frequency of 226 Hz in 60 ears of 30 adult individuals with normal hearing between the ages of 18–26. In the measurements TPP, Ytm, Vea and TW values were determined for both ears.ResultsIn two different tympanogram measurement results using 226 Hz click stimulus and 226 Hz probe tone were a statistically significant difference was found between Ytm, Vea and TW values in the left ear (p < 0.05) and a statistically significant difference was found between Ytm and Vea values in the right ear (p < 0.05). There was no significant difference between the right ear TPP and TW values, left ear TPP value (p > 0.05).ConclusıonThe current findings show that the comment of right and left ear tympanogram results should be evaluated according to two different measurement results using 226 Hz click stimulus and 226 Hz probe tone.

Feedback and observational learning differ in effectiveness during category learning in early school aged children and adults.

When learning new categories, do children benefit from the same types of training as adults? We compared the effects of feedback-based training with observational training in young adults (ages 18-25) and early school aged children (ages 6-7) across two different multimodal category learning tasks: conjunctive rule based and information integration. We used multimodal stimuli that varied across a visual feature (rotation speed of the "planet" stimulus) and an auditory feature (pitch frequency of a pure tone stimulus). We found an interaction between age and training type for the rule-based category task, such that adults performed better in feedback training than in observational training, whereas training type had no significant effect on children's category learning performance. Overall adults performed better than children in learning both the rule based and information integration category structures. In information integration category learning, feedback versus observational training did not have a significant effect on either adults' or children's category learning. Computational modelling revealed that children defaulted to univariate rules in both tasks. The finding that children do not benefit from feedback training and can learn successfully via observational learning has implications for the design of educational interventions appropriate for children.

EVIDENCE FOR AUDITORY STIMULUS-SPECIFIC ADAPTATION BUT NOT DEVIANCE DETECTION IN LARVAL ZEBRAFISH BRAINS.

Animals receive a constant stream of sensory input, and detecting changes in this sensory landscape is critical to their survival. One signature of change detection in humans is the auditory mismatch negativity (MMN), a neural response to unexpected stimuli that deviate from a predictable sequence. This process requires the auditory system to adapt to specific repeated stimuli while remaining sensitive to novel input (stimulus-specific adaptation). MMN was originally described in humans, and equivalent responses have been found in other mammals and birds, but it is not known to what extent this deviance detection circuitry is evolutionarily conserved. Here we present the first evidence for stimulus-specific adaptation in the brain of a teleost fish, using whole-brain calcium imaging of larval zebrafish at single-neuron resolution with selective plane illumination microscopy. We found frequency-specific responses across the brain with variable response amplitudes for frequencies of the same volume, and created a loudness curve to model this effect. We presented an auditory 'oddball' stimulus in an otherwise predictable train of pure tone stimuli, and did not find a population of neurons with specific responses to deviant tones that were not otherwise explained by stimulus-specific adaptation. Further, we observed no deviance responses to an unexpected omission of a sound in a repetitive sequence of white noise bursts. These findings extend the known scope of auditory adaptation and deviance responses across the evolutionary tree, and lay groundwork for future studies to describe the circuitry underlying auditory adaptation at the level of individual neurons.

Low-Level Auditory Processing Correlates With Language Abilities: An ERP Study Investigating Sequence Learning and Auditory Processing in School-Aged Children.

Auditory processing and procedural learning deficits have been associated with language learning difficulties. We investigated the relationship of these skills and school-age language abilities in children with and without a history of late talking using auditory event related potentials (ERPs). Late talking (i.e., slow early language development) increases the risk of persistent language difficulties, but its causes remain unknown. Participants in this study were children with varying language abilities (n = 60). Half of the participants (n = 30) had a history of late talking. We measured procedural learning by manipulating the predictability of sine tone stimuli in a passive auditory ERP paradigm. Auditory processing was tested by examining how the presence of noise (increasing perceptual demands) affected the ERPs. Contrary to our hypotheses on auditory processing and language development, the effect of noise on ERPs did not correlate with school-age language abilities in children with or without a history of late talking. Our paradigm failed to reveal interpretable effects of predictability leaving us unable to assess the effects of procedural learning. However, better language abilities were related to weaker responses in a 75-175 ms time window, and stronger responses in a 150-250 ms time window. We suggest that the weak early responses in children with better language ability reflect efficient processing of low-level auditory information, allowing deeper processing of later, high-level auditory information. We assume that these differences reflect variation in brain maturation between individuals with varying language abilities.

Multimodal convergence in the pedunculopontine tegmental nucleus: Motor, sensory and theta-frequency inputs influence activity of single neurons.

The pedunculopontine tegmental nucleus of the brainstem (PPTg) has extensive interconnections and neuronal-behavioural correlates. It is implicated in movement control and sensorimotor integration. We investigated whether single neuron activity in freely moving rats is correlated with components of skilled forelimb movement, and whether individual neurons respond to both motor and sensory events. We found that individual PPTg neurons showed changes in firing rate at different times during the reach. This type of temporally specific modulation is like activity seen elsewhere in voluntary movement control circuits, such as the motor cortex, and suggests that PPTg neural activity is related to different specific events occurring during the reach. In particular, many neuronal modulations were time-locked to the end of the extension phase of the reach, when fine distal movements related to food grasping occur, indicating strong engagement of PPTg in this phase of skilled individual forelimb movements. In addition, some neurons showed brief periods of apparent oscillatory firing in the theta range at specific phases of the reach-to-grasp movement. When movement-related neurons were tested with tone stimuli, many also responded to this auditory input, allowing for sensorimotor integration at the cellular level. Together, these data extend the concept of the PPTg as an integrative structure in generation of complex movements, by showing that this function extends to the highly coordinated control of the forelimb during skilled reach to grasp movement, and that sensory and motor-related information converges on single neurons, allowing for direct integration at the cellular level.

Auditory Event-related Potentials for Word Stimuli in Kannada Language Among Native Kannada Speakers with Dementia

Background: The P300 is a positive auditory event-related potential appearing around 300 msec post-oddball stimulus onset. Tone and monosyllabic stimuli have been widely used in P300 research, providing valuable insights into auditory perception, phoneme discrimination, language processing, and other cognitive processes. Bi-syllabic minimal pairs may be more challenging for some individuals because they require processing and discrimination of more complex phonemic structures. The aim of the study was to elicit and analyze the auditory event-related potentials for bi-syllabic word stimuli in the Kannada language among individuals with dementia. Method: The prospective study was conducted at the Department of Speech Pathology and Audiology. Ten native Kannada language speakers (five male; and five female) diagnosed with dementia, aged 55–70 years, were the participants. The naturally produced and recorded CVCV (Consonant vowel consonant vowel) tokens (/ko:ti/ and /ko:thi/ pair; /a: me/ and /a:ne pair) in Kannada were used in the auditory oddball paradigm. Results: The waveforms with positive peak for word (PPW) with clear morphology were used to obtain the latency and amplitude. Mean and Standard deviation (SD) value for the latency of the PPW was 545 ± 38 msec and the amplitude value of PPW was 2.5 ± 1.5 µV. Conclusion: The present study showed that when lengthier speech stimulus duration was used, the latency value of auditory event-related potential was higher. The study also showed that PPW is a reliable peak that could be used in the clinical population.

Lexical encoding of second language tones in English learners of Mandarin

The study investigates how native and non-native differences in tone perception influence lexical encoding of second language (L2) tones. Previous work shows that tone language listeners perceived tones as phonemic categories while non-tone language listeners relied more on psychoacoustic cues such as pitch height to discriminate stimulus tones. However, little is known about the influence of such differences in perception on L2 tonal encoding. In the present study, two experiments were conducted with nineteen English learners of Mandarin and 20 Mandarin native speakers. Experiment 1 was an ABX task. Results showed that while native speakers’ overall performance was superior to L2 listeners’, both groups poorly discriminated tone pairs with shared tone contours (i.e., T2-T3). Experiment 2 was a medium-lag repetition priming task. In the repetition condition, significant facilitations were observed in both language groups. In the minimal-tone-pair condition, despite T2-T3 contrasts posing greater challenge for both groups to accurately distinguish than other tonal contrasts as shown in Experiment 1, positive priming was observed only in the L2 group. The findings from the two experiments suggest that the L2 listeners, although quite proficient in Mandarin, have yet to achieve native-like competence in regard to lexical tones.

Fractured columnar small-world functional network organization in volumes of L2/3 of mouse auditory cortex.

The sensory cortices of the brain exhibit large-scale functional topographic organization, such as the tonotopic organization of the primary auditory cortex (A1) according to sound frequency. However, at the level of individual neurons, layer 2/3 (L2/3) A1 appears functionally heterogeneous. To identify if there exists a higher-order functional organization of meso-scale neuronal networks within L2/3 that bridges order and disorder, we used in vivo two-photon calcium imaging of pyramidal neurons to identify networks in three-dimensional volumes of L2/3 A1 in awake mice. Using tonal stimuli, we found diverse receptive fields with measurable colocalization of similarly tuned neurons across depth but less so across L2/3 sublayers. These results indicate a fractured microcolumnar organization with a column radius of ∼50 µm, with a more random organization of the receptive field over larger radii. We further characterized the functional networks formed within L2/3 by analyzing the spatial distribution of signal correlations (SCs). Networks show evidence of Rentian scaling in physical space, suggesting effective spatial embedding of subnetworks. Indeed, functional networks have characteristics of small-world topology, implying that there are clusters of functionally similar neurons with sparse connections between differently tuned neurons. These results indicate that underlying the regularity of the tonotopic map on large scales in L2/3 is significant tuning diversity arranged in a hybrid organization with microcolumnar structures and efficient network topologies.

Comparison of the Ling-6 Sound Test with Warble Tone Stimuli in Audiometry of Hearing-Impaired Children Using Hearing Aids Considering Different Prescriptions and Normal-Hearing Children

Background and Aim: Speech is a vital stimulus and the ultimate goal of hearing aid fitting to make the speech an audible signal. The purpose of this research was to investigate whether it is possible to track the threshold with speech phonemes and which of the two fitting methods of Desired Sensation Level version 5.0 (DSL v5.0) and National Acoustic Laboratories-Nonlinear 2 (NAL-NL2) provide better audibility for the phonemes. Methods: In this cross-sectional study, the unaided thresholds of 18 normal-hearing children and the aided thresholds of 15 hearing-impaired children aged 5-8 years were evaluated with two types of stimuli. DSL v5.0 and NAL-NL2 methods were used for hearing aid fitting in hearing-impaired children. Results: There was a significant relationship between the unaided and aided thresholds of each phoneme and the warble tone threshold at the corresponding frequency (p&lt;0.01), except for the phoneme /s/. The results showed a significant difference between the aided thresholds of each phoneme and the upper limit of the speech banana in the corresponding frequency for each method (Z=–4.99, p≤0.001). Conclusion: The results showed that phonemes could be used to assess unaided and aided thresholds. In the first fit, both methods estimated the amount of amplification that caused the average aided thresholds for these six phonemes for moderate to severe hearing loss to be positioned within the speech banana range, except for the average aided thresholds for the /s/ phoneme in the NAL-NL2 method that was placed outside the range. Keywords: Ling-6 sound test; pediatric audiometry; desired sensation level version 5.0; national acoustic laboratories-nonlinear 2

Effect of hearing loss on P300 measures

Background: P300 is among the first auditory responses in a collection of event-related or endogenous evoked responses. Hearing loss has drastically reduced cognitive abilities in individual adults. P300 is used as an electrophysiological tool to assess cognitive functions. This study was framed to compare the effect of hearing loss in P300 amplitude and latencies in Indian population. As no such study was carried out in Indian population, this study will be helpful in evaluating the correlation between hearing loss and cognitive function. Methods: We recruited a total of 60 participants out of which 30 were in group 1 having normal hearing and other 30 were included in group 2 having hearing loss. P300 was obtained using a Neurosoft instrument using tone burst stimuli The acquisition of tonal stimuli was carried out in a sound-treated room. Results: The t test value (t=4.75, p&lt;0.001) for P300 amplitude indicates that the difference between the mean among normal hearing and hearing-impaired adult was statistically significant. But the p=0.68 for P300 latency which indicates that the difference between the two groups is not statistically significant, which accepts hypothesis that There would not exist any relationship of P300 latency in normal hearing- and hearing-impaired adults. Pearson's correlation was found that hearing loss and amplitude of P300 has a strong negative correlation and latency of P300 has a poor positive correlation with hearing loss. Conclusions: Hearing loss affects the P300 measures. Due to hearing loss cognitive decline occurs which results in reduced amplitude and prolonged latency in P300.

Similar Tuning of Distortion-Product Otoacoustic Emission Ratio Functions and Cochlear Vibrations in Mice.

When elicited by two stimulus tones (at frequencies f1 and f2, f2 > f1), the amplitudes of specific distortion-product otoacoustic emission (DPOAE) components exhibit a characteristic bandpass shape as the ratio between f2 and f1 is varied. This bandpass shape has been attributed to various mechanisms including intracochlear resonance, suppression, and wave interference, and has been proposed to be related to cochlear frequency tuning. While human studies suggest modest correlations between psychophysical tuning and the tuning of DPOAE amplitude vs. f2/f1 ratio functions, a relationship between the latter and the tuning of cochlear mechanical responses has yet to be established. This was addressed here through direct comparisons of DPOAEs and cochlear vibrations in wild-type CBA/CaJ mice. DPOAEs were elicited using a fixed-f2, swept-f1 paradigm, and optical coherence tomography was used to measure displacements from cochlear locations with characteristic frequencies near f2. The tuning sharpness of 2f1-f2 DPOAE ratio functions was found to be remarkably similar to that of basilar membrane and/or tectorial membrane responses to single tones, with the tuning sharpness of all responses increasing similarly with decreasing stimulus level. This relationship was observed for f2 frequencies ranging from ~8 to 22 kHz. Intracochlear distortion products did not exhibit a bandpass shape as the f2/f1 ratio was varied, indicating that interference between distortion products traveling to the stapes may be responsible for the tuning of the DPOAE ratio function. While these findings suggest that DPOAE ratio functions could be used to noninvasively infer cochlear tuning, it remains to be determined whether this relationship holds in other species and for lower frequency regions.

Categorical Perception of Lexical Tones and Stops in Mandarin-Speaking Musicians and Nonmusicians

This study investigates the perception of Mandarin lexical tones and stops to examine the degree of overlap between music and language. Eighteen musicians and 21 nonmusicians participated in a typical categorical perception task. Results showed that musicians and nonmusicians had comparable degree of categorical perception of tones and stops. Compared to nonmusicians, musicians exhibited enhanced sensitivities to within-category lexical tone stimuli. However, this improved ability was not observed in the perception of stops. These findings imply that musical experience strengthens the acuity of subtle low-level acoustic variations between within-category lexical tone stimuli without interfering with the high-level phonological representations of lexical tones, and this facilitatory effect is selective and could not readily extend to stop consonants in native language.

The specificity of the auditory P300 responses and its association with clinical outcomes in youth with psychosis risk syndrome

BackgroundSchizophrenia often occurs in youth, and psychosis risk syndrome (PRS) occurs before the onset of psychosis. Assessing the neuropsychological abnormalities of PRS individuals can help in early identification and active intervention of mental illness. Auditory P300 amplitude defect is an important manifestation of attention processing abnormality in PRS, but it is still unclear whether there are abnormalities in the attention processing of rhythmic compound tone stimuli in PRS individuals, and whether the P300 amplitude induced by these stimuli is specific to PRS individuals and related to their clinical outcomes. MethodsIn total, 226 participants, including 122 patients with PRS, 51 patients with emotional disorders (ED), and 53 healthy controls (HC) were assessed. Baseline electroencephalography was recorded during the compound tone oddball task. The event-related potentials (ERPs) induced by rhythmic compound tone stimuli of two frequencies (20-Hz, 40-Hz) were measured. Almost all patients with PRS were followed up for 12 months and reclassified into four groups: PRS-conversion, PRS-symptomatic, PRS-emotional disorder, and PRS-complete remission. The differences in baseline ERPs were compared among the clinical outcome groups. ResultsRegardless of the stimulation frequency, the average P300 amplitude were significantly higher in patients with PRS than in those with ED (p = 0.003, d = 0.48) and in HC (p = 0.002, d = 0.44) group. The average P300 amplitude of PRS-conversion group was significantly higher than that of the PRS-complete remission (p = 0.016, d = 0.72) and HC group (p = 0.001, d = 0.76), and the average P300 amplitude of PRS-symptomatic group was significantly higher than that of the HC group (p = 0.006, d = 0.48). Regardless of the groups (PRS, ED, HC) or the PRS clinical outcome groups, the average P300 amplitude induced by 20-Hz tone stimulation was significantly higher than that induced by 40-Hz stimulation (ps < 0.001, Ƞ2 = 0.074–0.082). The average reaction times of PRS was significantly faster than that of ED (p = 0.01, d = 0.38), and the average reaction times of the participants to 20-Hz target stimulation was significantly faster than that to 40-Hz target stimulation (p < 0.001, d = 0.21). ConclusionThe auditory P300 amplitude induced by rhythmic compound tone stimuli is a specific electrophysiological manifestation of PRS, and the auditory P300 amplitude induced by compound tone stimuli shows promise as a putative prognostic biomarker for PRS clinical outcomes, including conversion to psychosis and clinical complete remission.

Sound frequencies detectable by grass (Ctenopharyngodon idella) and black (Mylopharyngodon pisceus) carp determined with auditory evoked potentials

Grass (Ctenopharyngodon idella) and black (Mylopharyngodon piceus) carp were imported to the United States as biocontrol agents in aquaculture facilities; however, due to intentional stocking or accidental release, invasive populations have become established. Invasive bigheaded carps display negative phonotaxis to sound, suggesting acoustic deterrents as a potential management tool. Grass and black carp frequency detection in response to 0.2–6 kHz sound was evaluated using auditory evoked potentials (AEPs) and determined for sound pressure level (SPL) and particle acceleration level (PAL). AEPs were detectable in response to pure tone stimuli from 0.2 to 4 kHz. The lowest SPL thresholds for grass carp were at 0.3 kHz (87.0 ± 3.6 dB re 1 μPa SPLrms; mean ± standard deviation), and the lowest PAL thresholds were at 0.4 kHz (–65.8 ± 3.2 dB re 1 ms−2 PALrms). For black carp, the lowest SPL and PAL thresholds were at 0.3 kHz (93.4 ± 3.0 dB re 1 μPa SPLrms, –60.8 ± 1.5 dB re 1 ms−2 PALrms). These results indicate that the ranges of detectable frequencies for grass and black carp overlap with those reported for bigheaded carps. However, behavioral studies are needed to determine potential efficacy of acoustic deterrents for these fish.

Gradients of response latencies and temporal precision of auditory neurons extend across the whole inferior colliculus.

Neural responses to acoustic stimulation have long been studied throughout the auditory system to understand how sound information is coded for perception. Within the inferior colliculus (IC), a majority of the studies have focused predominantly on characterizing neural responses within the central region (ICC), as it is viewed as part of the lemniscal system mainly responsible for auditory perception. In contrast, the responses of outer cortices (ICO) have largely been unexplored, though they also function in auditory perception tasks. Therefore, we sought to expand on previous work by completing a three-dimensional (3-D) functional mapping study of the whole IC. We analyzed responses to different pure tone and broadband noise stimuli across all IC subregions and correlated those responses with over 2,000 recording locations across the IC. Our study revealed there are well-organized trends for temporal response parameters across the full IC that do not show a clear distinction at the ICC and ICO border. These gradients span from slow, imprecise responses in the caudal-medial IC to fast, precise responses in the rostral-lateral IC, regardless of subregion, including the fastest responses located in the ICO. These trends were consistent at various acoustic stimulation levels. Weaker spatial trends could be found for response duration and spontaneous activity. Apart from tonotopic organization, spatial trends were not apparent for spectral response properties. Overall, these detailed acoustic response maps across the whole IC provide new insights into the organization and function of the IC.NEW & NOTEWORTHY Study of the inferior colliculus (IC) has largely focused on the central nucleus, with little exploration of the outer cortices. Here, we systematically assessed the acoustic response properties from over 2,000 locations in different subregions of the IC. The results revealed spatial trends in temporal response patterns that span all subregions. Furthermore, two populations of temporal response types emerged for neurons in the outer cortices that may contribute to their functional roles in auditory tasks.

Comparison of Apgar score and neonatal parameters between ET and ICSI foals

ICSI (Intracytoplasmic Sperm Injection) in the mare has been growing considerably in Brazil. This technique allows foals to be produced from mares with fertility problems, optimizes the use of rare or high-cost semen and embryos can be cryopreserved and achieve good pregnancy rates after transfer. An increasing number of ICSI foals are born each year and it is common to be asked by clients and veterinarians if these neonates have differences or altered behavior after birth compared to conventional embryo transfer (ET) foals. Therefore, the present study evaluated Apgar score and neonatal parameters in ICSI foals compared with conventional ET foals. A total of 25 Quarter Horse foals were evaluated, 11 born after conventional ET and 14 after ICSI. All parturitions were monitored and foals were evaluated. Heart and respiratory rates, muscle tone, and nasal stimulus were observed for the Apgar assessment (Knottenbelt.et.al. Equine Neonatol Med Surg 2004; 69-71) at 1 hour of life. Post-partum parameters evaluated were time to show a sucklingreflex, sit in sternal recumbency, stand and nurse. Regarding the Apgar score, there was no statistical difference (p = 0.8) comparing ET (7.64) and ICSI (7.57) foals. There was no statistical difference between groups (ET vs ICSI) for time to sit in sternal recumbency (8 vs 15.1 min, p = 0.1), show a suckling reflex (36.43 vs 34.25 min, p=0.9), stand (35.5 vs 39.92, p = 0.3) or nurse (108.88 vs 93.5 min, p = 0.4). The only detected difference was the time taken to start meconium elimination, ET foals showed an average of 122.75 compared to 61.75 min for the ICSI foals (p=0.02) but this difference has no biological significance, as values are within physiological parameters. Based on these results, foals produced by ICSI have the same neonatal parameters as conventional ET foals. Thus the same timeframes can be used to evaluate ET and ICSI neonates during the postpartum period. Acknowledgements: Fapesp 2020/10260-3 and RH Ranch (Campos dos Goytacazes – Brazil).

Abnormal auditory brainstem responses in an animal model of autism spectrum disorder

Auditory dysfunction is a common feature of autism spectrum disorder (ASD) and ranges from deafness to hypersensitivity. The auditory brainstem response (ABR) permits study of the amplitude and latency of synchronized electrical activity along the ascending auditory pathway in response to clicks and pure tone stimuli. Indeed, numerous studies have shown that subjects with ASD have ABR abnormalities. In utero exposure to the antiepileptic drug valproic acid (VPA) is associated with human cases of ASD and is used as an animal model of ASD. Previous studies have shown that VPA-exposed animals have significantly fewer neurons in the auditory brainstem and thalamus, reduced ascending projections to the auditory midbrain and thalamus and increased neuronal activation in response to pure tone stimuli. Accordingly, we hypothesized that VPA-exposed animals would have abnormal ABRs throughout their lifespans. We approached this hypothesis in two cohorts. First, we examined ABRs from both ears on postnatal day 22 (P22). Then, we examined monaural ABRs in animals at P28, 60, 120, 180, 240, 300 and 360. Our results suggest that at P22, VPA-exposed animals have elevated thresholds and increased peak latencies. However, by P60 these differences largely normalize with differences appearing only near hearing threshold. Additionally, our analysis revealed that maturation of ABR waves occurred at different trajectories in control and VPA-exposed animals. These results, together with our previous work, suggest that VPA exposure not only impacts total neuron number and connectivity, but also auditory evoked responses. Finally, our longitudinal analysis suggests that delayed maturation of auditory brainstem circuits may impact ABRs throughout the lifespan of the animal.