Habituation of the immobility response of guinea pigs to auditory stimuli

This paper discusses the development of a method to measure the habituation of the immobility response of guinea pigs.

How does the brain mediate interpretation of incongruent auditory emotions? The neural response to prosody in the presence of conflicting lexico-semantic cues

We frequently encounter conflicting emotion cues. This study examined how the neural response to emotional prosody differed in the presence of congruent and incongruent lexico-semantic cues. Two hypotheses were assessed: (i) decoding emotional prosody with conflicting lexico-semantic cues would activate brain regions associated with cognitive conflict (anterior cingulate and dorsolateral prefrontal cortex) or (ii) the increased attentional load of incongruent cues would modulate the activity of regions that decode emotional prosody (right lateral temporal cortex). While the participants indicated the emotion conveyed by prosody, functional magnetic resonance imaging data were acquired on a 3T scanner using blood oxygenation level-dependent contrast. Using SPM5, the response to congruent cues was contrasted with that to emotional prosody alone, as was the response to incongruent lexico-semantic cues (for the 'cognitive conflict' hypothesis). The right lateral temporal lobe region of interest analyses examined modulation of activity in this brain region between these two contrasts (for the 'prosody cortex' hypothesis). Dorsolateral prefrontal and anterior cingulate cortex activity was not observed, and neither was attentional modulation of activity in right lateral temporal cortex activity. However, decoding emotional prosody with incongruent lexico-semantic cues was strongly associated with left inferior frontal gyrus activity. This specialist form of conflict is therefore not processed by the brain using the same neural resources as non-affective cognitive conflict and neither can it be handled by associated sensory cortex alone. The recruitment of inferior frontal cortex may indicate increased semantic processing demands but other contributory functions of this region should be explored.

Analysis of transient otoacoustic emissions and brainstem evoked auditory potentials in neonates with hyperbilirubinemia

A hiperbilirrubinemia é tóxica às vias auditivas e ao sistema nervoso central, deixando sequelas como surdez e encefalopatia. OBJETIVOS: avaliar a audição de neonatos portadores de hiperbilirrubinemia, utilizando-se a pesquisa das emissões otoacústicas evocadas transientes (EOAET) e dos potenciais evocados auditivos do tronco encefálico (PEATE). Estudo prospectivo. CASUÍSTICA E MÉTODOS: Constituíram-se dois grupos: GI (n-25), neonatos com hiperbilirrubinemia; GII (n-22), neonatos sem hiperbilirrubinemia e sem fatores de risco para surdez. Todos os neonatos tinham até 60 dias de vida e foram submetidos à EOAET e ao PEATE. RESULTADOS: 12 neonatos de GI e 10 de GII eram meninas e 13 de GI e 12 de GII eram meninos. As EOAET estavam presentes em todas as crianças, porém com amplitudes menores em GI, especialmente nas frequências de 2 e 3KHz (p < 0,05). No PEATE, observou-se discreto prolongamento de PV e de LI-V em GI. As alterações observadas nesses testes não se correlacionaram aos níveis séricos da bilirrubinemia. CONCLUSÕES: em neonatos portadores de hiperbilirrubinemia, menores amplitudes das EOAET e discreto prolongamento de PV e de LI-V foram constatados indicando comprometimento coclear e retrococlear das vias auditivas, salientando-se a importância da utilização e da interpretação minuciosa de ambos os testes nessas avaliações.

Normative study and evaluation of age influence on Brainstem auditory evoked potentials in mixed breed dogs]

The aim of this paper was to obtain normative data of auditory evoked potentials from 34 mixed breed dogs and evaluate the age influence. The animals were divided in two groups of different ages and auditory evoked potential was performed with a 85dB stimulus intensity. Group 1 included 16 dogs between 1 and 8 years of age, and group 2 included 18 dogs with over 8 years of age. The length and head diameter were measured and there was no statistical difference between the two groups. In group 1, mean latencies of waves I, III, and V were 1.13; 2.64, and 3.45ms, and the intervals I-III, III-V, and I-V were 1.51; 0.81, and 2.32 ms, respectively. In group 2, the mean latencies of waves I, III and V were 1.15, 2.62, and 3.55ms, and the intervals I-III, III-V, and I-V were 1.47, 0.93, and 2.40ms, respectively. The latencies observed in this study were similar to previous studies conducted by other authors. It was observed that significant differences were present for wave V and intervals III-V and I-V latencies when comparing groups with different ages, consequently this characteristic must be considered during BAEP result interpretation.

Brainstem auditory evoked potential testing in Dalmatian dogs in Brazil

The brain stem auditory-evoked potential (BAEP) is an electrophysiologic test that detects and records the electrical activity in the auditory system from cochlea to midbrain, generated after an acoustic stimulus applied to the external ear. The aim of this study is to obtain normative data for BAEP in Dalmatian dogs in order to apply this to the evaluation of deafness and other neurologic disorders. BAEP were recorded from 30 Dalmatian dogs for a normative Brazilian study. Mean latencies for waves I, III, and V were 1.14 (±0.09), 2.62 (±0.10), and 3.46 (±0.14) ms, respectively. Mean inter-peak latencies for I-III, III-V, and I-V intervals were 1.48 (±0.17), 0.84 (±0.12), and 2.31 (±0.18) ms, respectively. Unilateral abnormalities were found in 16.7% of animals and bilateral deafness was seen in one dog. The normative data obtained in this paper is compatible with other published data. As far as we know this is the first report of deafness occurrence in Dalmatian dogs in Brazil.

Auditory stimulation with music influences the geometric indices of heart rate variability in response to the postural change maneuver

It is poor in the literature the behavior of the geometric indices of heart rate variability (HRV) during the musical auditory stimulation. The objective is to investigate the acute effects of classic musical auditory stimulation on the geometric indexes of HRV in women in response to the postural change maneuver (PCM). We evaluated 11 healthy women between 18 and 25 years old. We analyzed the following indices: Triangular index, Triangular interpolation of RR intervals and Poincar plot (standard deviation of the instantaneous variability of the beat-to beat heart rate [SD1], standard deviation of long-term continuous RR interval variability and Ratio between the short - and long-term variations of RR intervals [SD1/SD2] ratio). HRV was recorded at seated rest for 10 min. The women quickly stood up from a seated position in up to 3 s and remained standing still for 15 min. HRV was recorded at the following periods: Rest, 0-5 min, 5-10 min and 10-15 min during standing. In the second protocol, the subject was exposed to auditory musical stimulation (Pachelbel-Canon in D) for 10 min at seated position before standing position. Shapiro-Wilk to verify normality of data and ANOVA for repeated measures followed by the Bonferroni test for parametric variables and Friedmans followed by the Dunns posttest for non-parametric distributions. In the first protocol, all indices were reduced at 10-15 min after the volunteers stood up. In the protocol musical auditory stimulation, the SD1 index was reduced at 5-10 min after the volunteers stood up compared with the music period. The SD1/SD2 ratio was decreased at control and music period compared with 5-10 min after the volunteers stood up. Musical auditory stimulation attenuates the cardiac autonomic responses to the PCM.

Brainstem auditory-evoked potential in Boxer dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Response of cardiac autonomic modulation after a single exposure to musical auditory stimulation

The acute effects after exposure to different styles of music on cardiac autonomic modulation assessed through heart rate variability (HRV) analysis have not yet been well elucidated. We aimed to investigate the recovery response of cardiac autonomic modulation in women after exposure to musical auditory stimulation of different styles. The study was conducted on 30 healthy women aged between 18 years and 30 years. We did not include subjects having previous experience with musical instruments and those who had an affinity for music styles. The volunteers remained at rest for 10 min and were exposed to classical baroque (64-84 dB) and heavy metal (75-84 dB) music for 10 min, and their HRV was evaluated for 30 min after music cessation. We analyzed the following HRV indices: Standard deviation of normal-to-normal (SDNN) intervals, root mean square of successive differences (RMSSD), percentage of normal-to-normal 50 (pNN50), low frequency (LF), high frequency (HF), and LF/HF ratio. SDNN, LF in absolute units (ms (2) ) and normalized (nu), and LF/HF ratio increased while HF index (nu) decreased after exposure to classical baroque music. Regarding the heavy metal music style, it was observed that there were increases in SDNN, RMSSD, pNN50, and LF (ms (2) ) after the musical stimulation. In conclusion, the recovery response of cardiac autonomic modulation after exposure to auditory stimulation with music featured an increased global activity of both systems for the two musical styles, with a cardiac sympathetic modulation for classical baroque music and a cardiac vagal tone for the heavy metal style.

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.

Application of an auditory steady-state response test to evaluate the attenuation of hearing protection devices

This research aims to present a new method to get real attenuation of hearing protection devices, with good reproducibility and a small standard deviation, without relying on skills and cooperation individual. Thus the authors performed tests in 10 individuals without protection and after with two kinds of ear protections (ear plug and ear muffs), to get the threshold limit value in each of the 3 stages. For this, the research used an electrophysical exam, normally used in speech therapy, named ASSR (auditory steady-state response). The principle of this exam is put on individual’s head 3 electrodes, to capture electrical signs directly in auditory nerve. In summary, the authors presented the final results. The method proposed by ANSI (American National Standards Institute) indicated an attenuation of 27.6 dB for ear plugs, while the value found in this work was 16 dB; and for ear muffs, the ANSI method indicated 29.8 dB while the value found here was 28.5 dB.

Enhancing BOLD response in the auditory system by neurophysiologically tuned fMRI sequence

Auditory neuroscience has not tapped fMRI's full potential because of acoustic scanner noise emitted by the gradient switches of conventional echoplanar fMRI sequences. The scanner noise is pulsed, and auditory cortex is particularly sensitive to pulsed sounds. Current fMRI approaches to avoid stimulus-noise interactions are temporally inefficient. Since the sustained BOLD response to pulsed sounds decreases with repetition rate and becomes minimal with unpulsed sounds, we developed an fMRI sequence emitting continuous rather than pulsed gradient sound by implementing a novel quasi-continuous gradient switch pattern. Compared to conventional fMRI, continuous-sound fMRI reduced auditory cortex BOLD baseline and increased BOLD amplitude with graded sound stimuli, short sound events, and sounds as complex as orchestra music with preserved temporal resolution. Response in subcortical auditory nuclei was enhanced, but not the response to light in visual cortex. Finally, tonotopic mapping using continuous-sound fMRI demonstrates that enhanced functional signal-to-noise in BOLD response translates into improved spatial separability of specific sound representations.

A genetic screen for mutations that disrupt an auditory response in Drosophila melanogaster

Hearing is one of the last sensory modalities to be subjected to genetic analysis in Drosophila melanogaster. We describe a behavioral assay for auditory function involving courtship among groups of males triggered by the pulse component of the courtship song. In a mutagenesis screen for mutations that disrupt the auditory response, we have recovered 15 mutations that either reduce or abolish this response. Mutant audiograms indicate that seven mutants reduced the amplitude of the response at all intensities. Another seven abolished the response altogether. The other mutant, 5L3, responded only at high sound intensities, indicating that the threshold was shifted in this mutant. Six mutants were characterized in greater detail. 5L3 had a general courtship defect; courtship of females by 5L3 males also was affected strongly. 5P1 males courted females normally but had reduced success at copulation. 5P1 and 5N18 showed a significant decrement in olfactory response, indicating that the defects in these mutations are not specific to the auditory pathway. Two other mutants, 5M8 and 5N30, produced amotile sperm although in 5N30 this phenotype was genetically separable from the auditory phenotype. Finally, a new adult circling behavior phenotype, the pirouette phenotype, associated with massive neurodegeneration in the brain, was discovered in two mutants, 5G10 and 5N18. This study provides the basis for a genetic and molecular dissection of auditory mechanosensation and auditory behavior.

The relationship between the auditory brain-stem response and its reconstructed waveforms following discrete wavelet transformation

Objective: To examine the relationship between the auditory brain-stem response (ABR) and its reconstructed waveforms following discrete wavelet transformation (DWT), and to comment on the resulting implications for ABR DWT time-frequency analysis. Methods: ABR waveforms were recorded from 120 normal hearing subjects at 90, 70, 50, 30, 10 and 0 dBnHL, decomposed using a 6 level discrete wavelet transformation (DWT), and reconstructed at individual wavelet scales (frequency ranges) A6, D6, D5 and D4. These waveforms were then compared for general correlations, and for patterns of change due to stimulus level, and subject age, gender and test ear. Results: The reconstructed ABR DWT waveforms showed 3 primary components: a large-amplitude waveform in the low-frequency A6 scale (0-266.6 Hz) with its single peak corresponding in latency with ABR waves III and V; a mid-amplitude waveform in the mid-frequency D6 scale (266.6-533.3 Hz) with its first 5 waves corresponding in latency to ABR waves 1, 111, V, VI and VII; and a small-amplitude, multiple-peaked waveform in the high-frequency D5 scale (533.3-1066.6 Hz) with its first 7 waves corresponding in latency to ABR waves 1, 11, 111, IV, V, VI and VII. Comparisons between ABR waves 1, 111 and V and their corresponding reconstructed ABR DWT waves showed strong correlations and similar, reliable, and statistically robust changes due to stimulus level and subject age, gender and test ear groupings. Limiting these findings, however, was the unexplained absence of a small number (2%, or 117/6720) of reconstructed ABR DWT waves, despite their corresponding ABR waves being present. Conclusions: Reconstructed ABR DWT waveforms can be used as valid time-frequency representations of the normal ABR, but with some limitations. In particular, the unexplained absence of a small number of reconstructed ABR DWT waves in some subjects, probably resulting from 'shift invariance' inherent to the DWT process, needs to be addressed. Significance: This is the first report of the relationship between the ABR and its reconstructed ABR DWT waveforms in a large normative sample. (C) 2004 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.