RESUMEN
OBJECTIVE: This study aimed to look for a possible relationship between thyrotropin (TSH) values from neonatal bloodspot screening testing and newborn lower auditory pathway myelinization evaluated using the brainstem evoked response audiometry (ABR) test. METHODS: Sixty-two healthy full-term newborns without perinatal problems were enrolled in the study. TSH results were collected from neonatal bloodspot screening data and were below the test cut-off level (15µUI/mL). The TSH test was performed between three and seven days, and the ABR test was performed in the first 28 days of life. The newborns were divided into two groups: Group 1 (n = 35), TSH between 0 and 5µUI/mL, and group 2 (n = 27), TSH between 5 and 15µUI/mL. Data are presented as mean ± SD, median, or percentage, depending on the variable. RESULTS: Wave latency and interpeak interval values for Groups 1 and 2 were as follows: Wave I: 1.8 ± 0.1 and 1.7 ± 0.1; Wave III: 4.4 ± 0.1 and 4.4 ± 0.1; Wave V: 6.9 ± 0.1 and 6.9 ± 0.1; interval I-III: 2.6 ± 0.1 and 2.6 ± 0.1; interval I-V: 5.1 ± 0.1 and 5.1 ± 0.1; interval III-V: 2.4 ± 0.1 and 2.4 ± 0.1. There were no significant differences in ABR parameters between groups 1 and 2 (p > 0.05). Multiple regression analysis showed a slight significant negative correlation between TSH and wave I values (standardized ß = -0.267; p = 0.036), without observing any relationship with the other ABR waves recorded. CONCLUSIONS: This study investigated the relationship of TSH and auditory myelinization evaluated by ABR. It did not show a significant change in lower auditory pathway myelinization according to TSH levels in newborns with TSH screening levels lower than 15 µUI/mL.
Asunto(s)
Vías Auditivas , Tirotropina/sangre , Adulto , Audiometría de Respuesta Evocada , Vías Auditivas/crecimiento & desarrollo , Vías Auditivas/fisiología , Hipotiroidismo Congénito/sangre , Hipotiroidismo Congénito/fisiopatología , Estudios Transversales , Femenino , Humanos , Recién Nacido , MasculinoRESUMEN
Central auditory pathway maturation in children depends on auditory sensory stimulation. The objective of the present study was to monitor the cortical maturation of children with cochlear implants using electrophysiological and auditory skills measurements. The study was longitudinal and consisted of 30 subjects, 15 (8 girls and 7 boys) of whom had a cochlear implant, with a mean age at activation time of 36.4 months (minimum, 17 months; maximum, 66 months), and 15 of whom were normal-hearing children who were matched based on gender and chronological age. The auditory and speech skills of the children with cochlear implants were evaluated using GASP, IT-MAIS and MUSS measures. Both groups underwent electrophysiological evaluation using long-latency auditory evoked potentials. Each child was evaluated at three and nine months after cochlear implant activation, with the same time interval adopted for the hearing children. The results showed improvements in auditory and speech skills as measured by IT-MAIS and MUSS. Similarly, the long-latency auditory evoked potential evaluation revealed a decrease in P1 component latency; however, the latency remained significantly longer than that of the hearing children, even after nine months of cochlear implant use. It was observed that a shorter P1 latency corresponded to more evident development of auditory skills. Regarding auditory behavior, it was observed that children who could master the auditory skill of discrimination showed better results in other evaluations, both behavioral and electrophysiological, than those who had mastered only the speech-detection skill. Therefore, cochlear implant auditory stimulation facilitated auditory pathway maturation, which decreased the latency of the P1 component and advanced the development of auditory and speech skills. The analysis of the long-latency auditory evoked potentials revealed that the P1 component was an important biomarker of auditory development during the rehabilitation process.
Asunto(s)
Corteza Auditiva/crecimiento & desarrollo , Corteza Auditiva/fisiopatología , Vías Auditivas/crecimiento & desarrollo , Vías Auditivas/fisiopatología , Implantes Cocleares , Pérdida Auditiva Sensorineural/fisiopatología , Pérdida Auditiva Sensorineural/terapia , Estimulación Acústica , Estudios de Casos y Controles , Preescolar , Implantes Cocleares/psicología , Potenciales Evocados Auditivos/fisiología , Femenino , Audición/fisiología , Pérdida Auditiva Sensorineural/psicología , Humanos , Lactante , Estudios Longitudinales , Masculino , Tiempo de Reacción/fisiología , Habla/fisiologíaRESUMEN
Sound is an important part of man's contact with the environment and has served as critical means for survival throughout his evolution. As a result of exposure to noise, physiological functions such as those involving structures of the auditory and non-auditory systems might be damaged. We have previously reported that noise-exposed developing rats elicited hippocampal-related histological, biochemical and behavioral changes. However, no data about the time lapse of these changes were reported. Moreover, measurements of auditory pathway function were not performed in exposed animals. Therefore, with the present work, we aim to test the onset and the persistence of the different extra-auditory abnormalities observed in noise-exposed rats and to evaluate auditory pathway integrity. Male Wistar rats of 15 days were exposed to moderate noise levels (95-97 dB SPL, 2 h a day) during one day (acute noise exposure, ANE) or during 15 days (sub-acute noise exposure, SANE). Hippocampal biochemical determinations as well as short (ST) and long term (LT) behavioral assessments were performed. In addition, histological and functional evaluations of the auditory pathway were carried out in exposed animals. Our results show that hippocampal-related behavioral and biochemical changes (impairments in habituation, recognition and associative memories as well as distortion of anxiety-related behavior, decreases in reactive oxygen species (ROS) levels and increases in antioxidant enzymes activities) induced by noise exposure were almost completely restored by PND 90. In addition, auditory evaluation shows that increased cochlear thresholds observed in exposed rats were re-established at PND 90, although with a remarkable supra-threshold amplitude reduction. These data suggest that noise-induced hippocampal and auditory-related alterations are mostly transient and that the effects of noise on the hippocampus might be, at least in part, mediated by the damage on the auditory pathway. However, we cannot exclude that a different mechanism might be responsible for the observed hippocampal-related changes.
Asunto(s)
Vías Auditivas/fisiología , Encéfalo/crecimiento & desarrollo , Encéfalo/metabolismo , Ruido/efectos adversos , Especies Reactivas de Oxígeno/metabolismo , Estimulación Acústica , Factores de Edad , Animales , Animales Recién Nacidos , Proteínas de Arabidopsis , Vías Auditivas/crecimiento & desarrollo , Reacción de Prevención , Catalasa/metabolismo , Conducta Exploratoria/fisiología , Femenino , Pruebas Auditivas , Masculino , Aprendizaje por Laberinto , Proteínas Nucleares , Ratas , Ratas Wistar , Reconocimiento en Psicología , Superóxido Dismutasa/metabolismo , Factores de TiempoRESUMEN
The Calyx of Held (CoH) synapse is the largest synapse in mammals. It is located in the medial nucleus of the trapezoid body (MNTB) and forms part of the auditory pathway. Modest GABAergic signaling is present in the CoH before hearing onset, when glutamatergic transmission predominates. In mice, after postnatal day 12, the absolute strength of glycinergic transmission increases markedly, while GABAergic signaling remains constant. The persistent GABAergic transmission in the MNTB is mediated by a slowly desensitizing component. In this study we recorded GABA-mediated responses from postsynaptic principal neurons (PPNs) of the MNTB and found that they are sensitive to TPMPA, suggesting the involvement of GABAρ subunits. RT-PCR and immunohistofluorescence in the MNTB confirmed GABAρ expression in PPNs. Interestingly, GABAρ3 was present only before hearing onset, and there was a switch to GABAρ1 and GABAρ2 expression in adult animals.
Asunto(s)
Vías Auditivas/metabolismo , Tronco Encefálico/metabolismo , Receptores de GABA-A/metabolismo , Animales , Animales Recién Nacidos , Vías Auditivas/crecimiento & desarrollo , Tronco Encefálico/crecimiento & desarrollo , Técnicas In Vitro , Ratones , Neuronas/metabolismo , Técnicas de Placa-Clamp , Subunidades de Proteína/metabolismo , Sinapsis/metabolismoRESUMEN
OBJECTIVE: The maturation pattern of the envelope following response (EFR) was described using rats as an experimental model. DESIGN: EFRs were recorded in animals at different postnatal ages (15, 20, 25, 35, and 70 postnatal days) in response to broadband noise (BBN) and tones of 8000 and 4000 Hz modulated in amplitude using a continuous sweep of modulation frequencies. Responses were analysed in the 90-190 Hz modulation frequency (MF) range. STUDY SAMPLE: Forty individuals (eight individuals for each age bracket) were included in the present study. RESULTS: During maturation, the MF at which the maximum amplitude was obtained (BMF, best modulation frequency) shifted to higher values when animals were stimulated with tones. At the same time, the amplitude of the response at the BMF increased. For every group of animals, the amplitude of the response continuously decreased for MFs higher than the BMF. However, less steep decreases of amplitude were obtained as animals became adults. CONCLUSIONS: These results provide normative data regarding the maturation of the EFR in rats. They provide information for the development of predictor models to estimate the temporal resolution of the auditory system during maturation.
Asunto(s)
Envejecimiento , Vías Auditivas/crecimiento & desarrollo , Percepción Auditiva , Percepción del Tiempo , Estimulación Acústica , Factores de Edad , Animales , Audiometría de Respuesta Evocada , Potenciales Evocados Auditivos , Ratas , Ratas Wistar , Procesamiento de Señales Asistido por Computador , Factores de TiempoRESUMEN
BACKGROUND: the long latency auditory evoked potentials (LLAEP) provide objective data about the function of hearing cortical structures. AIM: to characterize the maturation of the central hearing system in normally hearing children. METHOD: record of LLAEP of fifty-six subjects with hearing tresholds within normal limits, of both genders, being 46 children and 10 adults. With the availability of two recording channels, one was directed to register the LLAEP and the other, to record the artifact generated by ocular movement, aiming at its control. The potentials were recorded with subjects in an alert state, through electrodes positioned in Cz (active) and A2 (reference), and the ocular movements, through electrodes in the left supra and infra-orbital positions; the ground electrode was placed in A1. The morphology and the values of latency and of amplitude for components P1, N1 and P2, according to age, were analyzed. In order to verify the reproducibility of the recorded potentials, a double blind study was carried out, by introducing the analysis of another evaluator. RESULTS: the double blind study did not present statistically significant differences between the analyses. With the increase in age there was an improvement in the morphology and a decrease in the latency values of components P1, N1 and P2. Also there was a decrease in the amplitude of component P1 and no variation in the amplitude values was observed for components N1 and P2. No statistically significant difference was observed between genders. CONCLUSION: the maturational process of the central hearing system occurs gradually, being the greatest changes observed when comparing children and adults.
Asunto(s)
Estimulación Acústica/métodos , Vías Auditivas/fisiología , Percepción Auditiva/fisiología , Potenciales Evocados Auditivos/fisiología , Tiempo de Reacción/fisiología , Adulto , Vías Auditivas/crecimiento & desarrollo , Niño , Preescolar , Método Doble Ciego , Femenino , Humanos , Masculino , Variaciones Dependientes del Observador , Reproducibilidad de los ResultadosRESUMEN
BACKGROUND: the long latency auditory evoked potentials (LLAEP) provide objective data about the function of hearing cortical structures. AIM: to characterize the maturation of the central hearing system in normally hearing children. METHOD: record of LLAEP of fifty-six subjects with hearing tresholds within normal limits, of both genders, being 46 children and 10 adults. With the availability of two recording channels, one was directed to register the LLAEP and the other, to record the artifact generated by ocular movement, aiming at its control. The potentials were recorded with subjects in an alert state, through electrodes positioned in Cz (active) and A2 (reference), and the ocular movements, through electrodes in the left supra and infra-orbital positions; the ground electrode was placed in A1. The morphology and the values of latency and of amplitude for components P1, N1 and P2, according to age, were analyzed. In order to verify the reproducibility of the recorded potentials, a double blind study was carried out, by introducing the analysis of another evaluator. RESULTS: the double blind study did not present statistically significant differences between the analyses. With the increase in age there was an improvement in the morphology and a decrease in the latency values of components P1, N1 and P2. Also there was a decrease in the amplitude of component P1 and no variation in the amplitude values was observed for components N1 and P2. No statistically significant difference was observed between genders. CONCLUSION: the maturational process of the central hearing system occurs gradually, being the greatest changes observed when comparing children and adults.
TEMA: os potenciais evocados auditivos de longa latência (PEALLs) fornecem dados objetivos sobre a funcionalidade das estruturas centrais auditivas. OBJETIVO: caracterizar a maturação do sistema auditivo central em crianças com audição normal. MÉTODO: registro dos PEALLs de 56 indivíduos ouvintes normais, de ambos os sexos, sendo 46 crianças e 10 adultos. Com a disponibilidade de dois canais de registro, um foi destinado à captação dos PEALLs e outro, ao registro do artefato gerado pelo movimento ocular, visando ao seu controle. Os potenciais foram registrados com os indivíduos em estado de alerta, por meio de eletrodos posicionados em Cz (ativo) e A2 (referência) e os movimentos oculares, por eletrodos em posição supra e infra-orbital esquerda; o eletrodo terra foi colocado em A1. Foram analisados a morfologia e os valores de latência e amplitude dos componentes P1, N1 e P2, de acordo com a idade. Para verificar a reprodutibilidade dos registros, foi realizado um estudo duplo-cego com a introdução da análise de outra avaliadora. RESULTADOS: o estudo duplo-cego não mostrou diferenças estatisticamente significantes entre as análises. Com o avanço da idade, houve melhora na morfologia e diminuição nos valores de latência dos componentes P1, N1 e P2. O componente P1 teve sua amplitude diminuída e não foi observada variação nos valores de amplitude dos componentes N1 e P2. Não foi observada diferença estatisticamente significante entre os sexos. CONCLUSÃO: o processo maturacional do sistema auditivo central acontece de maneira gradativa, sendo as maiores modificações observadas ao se comparar crianças e adultos.
Asunto(s)
Adulto , Niño , Preescolar , Femenino , Humanos , Masculino , Estimulación Acústica/métodos , Vías Auditivas/fisiología , Percepción Auditiva/fisiología , Potenciales Evocados Auditivos/fisiología , Tiempo de Reacción/fisiología , Vías Auditivas/crecimiento & desarrollo , Método Doble Ciego , Variaciones Dependientes del Observador , Reproducibilidad de los ResultadosRESUMEN
UNLABELLED: The human peripheral auditory system is fully developed at birth; however, myelination continues for several years in the higher auditory pathways. The aim of the present study was to assess the maturation course of the frequency and duration pattern tests and the middle latency response (MLR). One hundred and fifty normal participants ranging from 7 to 16 years of age were tested using conventional protocols. Results showed increased performance with increased age on both the behavioral tests up to age 12. However, there was no significance change across this age range for either latency or amplitude measures on the MLR. The MLR showed less variability for older children. High variability was a likely factor for the statistical outcome of the MLR. The data obtained on the frequency and duration pattern tests were applied to the development of age related norms. LEARNING OUTCOMES: As a result of this experience, the reader will obtain information about (a) the normal development of the auditory system; (b) performance of children on several standard tests of auditory function; and (c) the characteristics of MLRs in the same group of children.
Asunto(s)
Vías Auditivas/fisiología , Potenciales Evocados Auditivos/fisiología , Adolescente , Análisis de Varianza , Audiometría de Tonos Puros , Vías Auditivas/crecimiento & desarrollo , Umbral Auditivo , Conducta , Distribución de Chi-Cuadrado , Niño , Femenino , Humanos , Masculino , Tiempo de ReacciónRESUMEN
TEMA: maturação do processamento auditivo em escolares com e sem dificuldades escolares. OBJETIVO: verificar a melhora de resposta com o aumento da idade em habilidades do Processamento Auditivo em crianças com idades de oito, nove e dez anos, com e sem dificuldades escolares, e realizar estudo comparativo. MÉTODO: foram avaliadas 89 crianças sem queixas de dificuldades escolares (Grupo I) e 60 com queixas de dificuldades escolares (Grupo II). Os testes do processamento auditivo aplicados foram o Pediatric Speech Inteligibility (PSI), o Fala com Ruído, o Dicótico Não Verbal (DNV) e o Sttagered Spondaic Word (SSW). RESULTADOS: no Grupo I, foi verificado melhor desempenho na resposta entre as idades de oito e dez anos para todos os testes, mas com diferenças estatisticamente significantes apenas para os testes PSI e SSW. Para o Grupo II, também foi verificado melhor desempenho na resposta com o aumento da idade, com diferenças estatisticamente significantes, para todos os testes. No estudo comparativo entre o Grupo I e o Grupo II, para o desempenho em cada teste e para cada faixa etária, verificou-se melhor desempenho no grupo de crianças sem dificuldades escolares, nas três faixas etárias, nos testes PSI, DNV e SSW. CONCLUSAO: neste estudo, verificou-se a melhora de resposta com o aumento da idade, estatisticamente significante, no desempenho de habilidades do processamento auditivo para as faixas etárias entre oito e dez anos, tanto em crianças sem dificuldades escolares como nas com queixa de dificuldades escolares. No estudo comparativo, verificou-se que as crianças do grupo com dificuldades escolares apresentaram pior desempenho em todos testes aplicados e para as três faixas etárias, sugerindo atraso na maturação das habilidades do processamento auditivo neste grupo.
Asunto(s)
Humanos , Masculino , Femenino , Niño , Vías Auditivas/crecimiento & desarrollo , Percepción Auditiva/fisiología , Pruebas Auditivas , Audición/fisiología , Discapacidades para el Aprendizaje/diagnóstico , Aprendizaje/fisiología , Distribución por Edad , Factores de Edad , Trastornos de la Percepción Auditiva/diagnóstico , Estudios de Casos y Controles , Pruebas de Audición Dicótica , Inteligibilidad del HablaRESUMEN
BACKGROUND: Auditory processing maturation in school children with and without learning difficulties. AIM: To verify response improvement with the increase in age of the auditory processing skills in school children with ages ranging from eight to ten years, with and without learning difficulties and to perform a comparative study. METHOD: Eighty-nine children without learning complaints (Group 1) and 60 children with learning difficulties (Group II) were assessed. The used auditory processing tests were: Pediatric Speech Intelligibility (PSI), Speech in Noise, Dichotic Non-Verbal (DNV) and Staggered Spondaic Word (SSW). RESULTS: A better performance was observed for Group I between the ages of eight and ten in all of the used tests. However, the observed differences were statistically significant only for PSI and SSW. For Group II, a better performance was also observed with the increase in age, with statistically significant differences for all of the used tests. Comparing the results between Groups I and II, a better performance was verified for children with no learning difficulties, in the three age groups, in PSI, DNV and SSW. CONCLUSION: A statistically significant improvement was verified in the responses of the auditory processing with the increase in age, for the ages between eight and ten years, in children with and without learning difficulties. In the comparative study, it was verified that children with learning difficulties presented a lower performance in all of the used tests in the three age groups. This suggests, for this group, a delay in the maturation of the auditory processing skills.
Asunto(s)
Vías Auditivas/fisiopatología , Percepción Auditiva/fisiología , Pruebas Auditivas , Audición/fisiología , Discapacidades para el Aprendizaje/fisiopatología , Aprendizaje/fisiología , Distribución por Edad , Factores de Edad , Vías Auditivas/crecimiento & desarrollo , Trastornos de la Percepción Auditiva/diagnóstico , Estudios de Casos y Controles , Niño , Pruebas de Audición Dicótica , Femenino , Humanos , Masculino , Inteligibilidad del HablaRESUMEN
The onset of hearing in anesthetized South American opossums (Monodelphis domestica) was determined by the measurement of evoked potentials to click stimuli from the vertex of the skull immediately over the inferior colliculus. Evoked potentials were first recorded at postnatal day 24 at a threshold of 83 dB SPL; thresholds declined over subsequent weeks to below 58 dB at 40 days. Isolation calls emitted by the pups had stereotypic spectra with peaks at near 13 kHz and an octave higher. Such calls declined in frequency by day 32 and were not emitted at day 40. The peak frequency of the calls matched very closely the best frequency of hearing of adult Monodelphis. The number of synapses in the inferior colliculus increased at day 26; when plotted in relation to the number of cells, synaptic density increased steeply from day 27 after the animal had begun to hear. This suggests that environmental sound has a potent effect on the development of synapses in the auditory system.