Professional research project (Au.D.)--University of South Florida, 2003. / Title from PDF of title page. / Document formatted into pages; contains 20 pages. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The purpose of this study was to determine the effects of an atypical pattern of early acoustic stimulation on auditory development. Previous human research suggests that the acoustic environment of pre-term human infants in the Neonatal Intensive Care Unit (NICU) negatively affects some aspects of auditory development. Animal research suggests that premature auditory stimulation interrupts auditory development. Because mice are born before their auditory systems are developed, they make an excellent model for research on fetal and postnatal plasticity of the auditory system. The premature auditory state of newborn mice is similar to that of the NICU pre-term infant, albeit, natural for mice C57 mouse pups were exposed to an augmented acoustic environment (AAE) of a nightly 12-hour regiment of 70 dB SPL noise burst, beginning before age 12 days (onset of hearing) and lasting for one month. / ABSTRACT: The prepulse inhibition (PPI) of mice exposed to the AAE was compared to that of non-exposed mice to observe short-term and long-term effects. Results showed that the prepulse inhibition of the AAE exposed mice did not differ significantly from that of the non-exposed mice. However, it is possible that the measurement used, PPI, may not have been appropriate or that the AAE may not have been an appropriate simulation of the NICU environment. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Functional MRI or Functional Magnetic Resonance Imaging (fMRI) is a type of specialized MRI scan which measures the hemodynamic response related to neural activity in the brain or spinal cord of humans and animals. Due to its relatively low invasiveness, absence of radiation exposure, and relatively wide availability, functional MRI has come to dominate the brain mapping field since the early 1990s. The objective of this thesis work is to develop and apply functional MRI methods at 7 Tesla, for in vivo investigation of rodent visual and auditory system. Firstly, the development of the rat visual pathway was studied by blood oxygenation level–dependent (BOLD) contrast from the time of eyelid opening (P14) to adulthood (P60) in normal rat brain. By studying BOLD-fMRI measurements in the normal brain superior colliculus (SC), we determined that the regional BOLD response undergoes a systematic increase in amplitude especially over the third postnatal week. Secondly, the potential for plasticity of the rodent superior colliculus (SC) was studied using BOLD fMRI. By studying BOLD-fMRI measurements in the SC of three groups of rats (normal, HI-injured with left SC partially damaged and HI-injured with left SC completely damaged), we can evaluate the extent of plastic changes, compensatory and transneuronal plasticity after varying degrees of SC injury. We also applied BOLD-fMRI using very short repetition time (TR) of 0.2s on rats to measure the difference in response temporal dynamics between the SC and LGN, which has not been measured conclusively or with high temporal resolution. The primary finding in this study is that there is an approximately 0.8s difference between the BOLD responses of the rat contralateral SC and LGN to the visual stimuli. In addition, the amplitude of the SC response is larger than that of the LGN. Thirdly, BOLD-fMRI is used to measure the SC hemodynamic responses, in normal adult Sprague-Dawley (SD) rats, during a dynamic visual stimulus similar to those used in long-range apparent motion studies. The stimulation paradigm mimic effective speeds of motion between 7 and 164?/s, the results suggest that the SC is sensitive to slow moving visual stimuli but the hemodynamic response is reduced at higher speeds. Finally, BOLD-fMRI is used to study hemodynamic response temporal dynamics in the superior colliculus (SC) and inferior colliculus (IC) following visual and auditory associated stimulation. Our results show the baselines of SC BOLD signal (in two sides) increase during the ON period of auditory stimulation, which demonstrate that auditory stimulation can increase ROI activation signal intensity in superior colliculus (SC). The previous dominant theory is that individual senses each have separate areas of the brain dedicated to processing each sense, while the individual sense perceptions are integrated together to produce a multi-sensory experience. As a result of new research over the past several years, however, this view has been challenged by studies showing that processing in the visual area of the brain can be directly influenced by hearing and touch. All these discoveries represent a new view of how the brain is actually organized. / published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

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INTRODUÇÃO: Uma possibilidade de pesquisa em audição é a supressão das emissões otoacústicas, que verifica a diminuição de sua magnitude a partir de estimulação acústica simultânea. Acredita-se que esta diminuição ocorra devido ao papel da via eferente auditiva. OBJETIVO: verificar a atividade do sistema auditivo eferente, por meio da supressão contralateral das emissões otoacústicas, em neonatos com e sem indicadores de risco para perda auditiva. MÉTODO: foram avaliados 21 neonatos com indicadores de risco para perda auditiva (grupo estudo) e 30 neonatos sem indicadores (grupo controle) por meio das emissões otoacústicas evocadas por estímulo de freqüência específica \"tone burst\" em 2000 e em 4000 hertz, na ausência e na presença de ruído branco contralateral. RESULTADOS: a orelha direita e o grupo controle apresentaram vantagem na amplitude das EOA TB. Os valores médios de \"Response\" para 2000 hertz foram 17,73 dB no grupo controle e 16,55 dB no grupo estudo, para o gênero feminino e 16,63 dB no grupo controle e 16,12 dB no grupo estudo, para o gênero masculino. Para 4000 hertz, os valores médios de \"Response\" foram 14,63 dB no grupo controle e 15,09 dB no grupo estudo, para o gênero feminino e 18,57 dB no grupo controle e 15,06 dB no grupo estudo, para o gênero masculino. Na supressão, houve vantagem da orelha direita, do grupo controle para o gênero feminino e do grupo estudo para o gênero masculino, embora sem plena significância estatística. Os valores médios de supressão para a variável \"Response\" em 2000 hertz foram 1,66 dB no grupo controle e 0,84 dB no grupo estudo, para o gênero feminino e 1,41 dB no grupo controle e 2,07 dB no grupo estudo, para o gênero masculino. Para 4000 hertz, os valores médios da supressão em \"Response\" foram 1,29 dB no grupo controle e 0,98 dB no grupo estudo, para o gênero feminino e 1,75 dB no grupo controle e 2,14 dB no grupo estudo, para o gênero masculino. CONCLUSÃO: A partir de estímulos de freqüência específica, em 2000 e em 4000 hertz, foi possível verificar o efeito inibitório da via eferente auditiva sobre a amplitude das EOA, em neonatos. A utilização de estímulos de freqüência específica pode contribuir para a avaliação da função auditiva periférica e central nesta população. / INTRODUCTION: A possible hearing research is the suppression of otoacoustic emissions which verifies a decrease of its magnitude from a simultaneous acoustic stimulation. It is assumed that this decrease occurs because of the role of the auditory efferent pathway. AIM: to verify the activity of the auditory efferent pathway by the contralateral suppression of OAE in neonates with and without risk factors for hearing loss. MEHOD: 21 neonates at risk for hearing loss (study group), and 30 neonates without risk factors for hearing loss (control group) were assessed through otoacoustic emissions evoked by a frequency specific stimulus, \"tone burst\", at 2000 and at 4000 hertz, with and without contralateral white noise. RESULTS: the right ear and the control group presented advantage in the amplitude of OAE TB. The mean values of \"Response\" at 2000 hertz were 17,73 dB in the control group and 16,55 dB in the study group, for female subjects, and 16,63 dB in the control group and 16,12 dB in the study group, for male subjects. At 4000 hertz, the mean values of \"Response\" were 14,63 dB in the control group and 15,09 dB in the study group, for female subjects and 18,57 dB in the control group and 15,06 dB in the study group, for male subjects. In the suppression, there was an advantage of the right ear, of the control group for female subjects, and of the study group for male subjects, although without statistical significance. The mean values of suppression for the variable \"Response\" at 2000 hertz were 1,66 dB in the control group and 0,84 dB in the study group, for female subjects, and 1,41 dB in the control group and 2,07 dB in the study group, for male subjects. At 4000 hertz, the mean values of suppression for \"Response\" were 1,29 dB in the control group and 0,98 dB in the study group, for female subjects, and 1,75 dB in the control group and 2,14 dB in the study group, for male subjects. CONCLUSION: From frequency-specific stimuli at 2000 and at 4000 hertz, it was possible to verify the inhibitory effect of the auditory efferent pathway upon the amplitude of otoacoustic emissions in neonates. The use of frequencyspecific stimuli may contribute for the assessment of the central auditory function in this population.

Introdução: Entender como estímulos acústicos complexos são codificados ao longo da via auditiva e como este processamento está relacionado em níveis mais inferiores e superiores da via, pode nos levar ao melhor entendimento de processos que subjazem a comunicação humana normal e alterada. Baseado na literatura que descreve anormalidades no processamento auditivo temporal em crianças com Distúrbio Especifico de Linguagem (DEL), nós hipotetizamos que dificuldades no processamento de fala estão diretamente relacionadas ao déficit na codificação neural destes sons, nos diferentes níveis da via auditiva, tanto em crianças com DEL quanto em crianças com Transtorno de Processamento Auditivo (Central) TPA(C). Objetivos: Verificar a representação e o processamento de sinais acústicos de diferentes complexidades no sistema auditivo por meio de testes comportamentais, eletroacústicos e eletrofisiológicos em indivíduos com TPA(C), DEL e desenvolvimento típico (DT). Métodos: As avaliações comportamentais, eletroacústicas e eletrofisiológicas (avaliação comportamental do processamento auditivo central, medidas de supressão das emissões otoacústicas por estimulo transiente, potencial evocado auditivo de tronco encefálico (PEATE) utilizando estímulo clique e estímulo de fala, o MMN evocado por estímulo de fala e o P300 com estímulo tone burst) foram realizadas em 75 crianças, com idade entre 6 a 12 anos, sendo 25 crianças pertencentes ao grupo DT, 25 crianças ao grupo TPA(C) e 25 crianças ao grupo DEL. A análise dos resultados foi realizada através da comparação entre os três grupos. Além disso, foi verificada a sensibilidade e especificidade do PEATE com fala para crianças brasileiras. Resultados: As análises das respostas apresentadas pelo grupo DT em comparação as respostas apresentadas pelos grupos TPA(C) e DEL revelaram nesses dois grupos a ocorrência de codificação neural anormal para diferentes características acústicas (temporais e/ou espectrais) presentes nos diferentes estímulos acústicos utilizados no presente estudo. Além disso, observou-se piores padrões de resposta no grupo DEL em comparação ao grupo TPA(C), em pelo menos uma variável em todas as avaliações, sugerindo possíveis diferenciações entre esses dois diagnósticos. Conclusão: Estes dados mostraram que a representação ineficiente de componentes cruciais de sons, principalmente sons de fala, poderia contribuir para as dificuldades encontradas nas crianças com TPA(C) e DEL. Além disso, esses achados indicam que processos neurais mediados pelas diferentes estações na via auditiva são diferentes entre alteração de processamento auditivo e linguagem / Introduction: Understanding how complex acoustic stimuli are encoded along the auditory pathway and how this processing is related to lower and higher levels from the pathway can help us to better understand the processes underlying normal and altered human communication. Based on the literature describing abnormalities in temporal auditory processing in children with specific language impairment (SLI), we hypothesized that difficulties in speech processing are directly related in the neural encoding deficits of these sounds at different levels in the auditory pathway, both in children with SLI as well as children with (central) auditory processing disorder (C)APD. Objectives: Verify the representation and processing of acoustic signals of different complexities in the auditory system using behavioral, electroacoustic and electrophysiologic tests in patients with (C)APD, SLI compared to a Typical Development (TD). Methods: The behavioral assessments, electroacoustic and electrophysiologic (behavioral assessment of central auditory processing, measures on the suppression of transient otoacoustic emissions stimulus, Click Evoked-ABR and Speech-Evoked ABR, MMN to speech stimuli and P300 to tone burst stimuli) were tested in 75 children (6 to 12 years old). The children were arranged in three groups: 25 children in the TD group, 25 children in the (C)APD group and 25 children in the SLI group. The results analysis was performed by comparing the three groups. In addition, the sensitivity and specificity of the Speech-Evoked ABR was verified Brazilian children. Results: Analysis of the responses provided for TD group compared to APD(C) and SLI groups revealed abnormal neural encoding for different acoustic features (temporal and/or spectral) in the different acoustic stimuli used in this study. In addition, the SLI group exhibited poor responses in comparison to (C)APD, at least for one variable in all evaluations, suggesting possible differences between these two diagnoses. In addition, worse response patterns were observed in the SLI group compared to (C)APD group by at least one variable in all of the evaluations, suggesting possible differences between these two diagnoses. Conclusion: These data showed that the inefficient representation of the crucial sound components, especially speech sounds, could contribute to difficulties found in childrens with (C)APD and SLI. Furthermore, these findings indicate that neural processes mediated by different stations in the auditory pathways are different between auditory processing and language disorders

Introdução: Zumbido é um sintoma de alterações nas vias auditivas com etiologia variada. Muitos pacientes com perda auditiva possuem zumbido e um dos tratamentos é o uso dos aparelhos auditivos. Os aparelhos auditivos amplificam os sons externos e os pacientes passam a perceber melhor os sons do ambiente, diminuindo a percepção do zumbido e proporcionando melhora na entrada do som por meio do enriquecimento sonoro. Contudo, é visto na literatura que alguns pacientes não observam a diminuição do incômodo e da percepção do zumbido ao utilizar os aparelhos auditivos. O estudo da audição periférica nestes pacientes poderia fornecer informações sobre fatores que dificultam a redução da percepção do zumbido com o uso de aparelhos auditivos. Objetivo: Avaliar as características audiológicas de pacientes com zumbido e perda de audição e verificar se há diferenças entre o grupo que obteve redução na percepção do zumbido com o uso de aparelhos auditivos e o grupo que não obteve o mesmo benefício. Método: Foram avaliados 29 sujeitos, divididos em dois Grupos, sendo Grupo I (GI) composto por 20 sujeitos que observaram melhora na percepção do zumbido após dois meses de uso dos aparelhos auditivos, e o Grupo II (GII) composto por nove, que não observaram melhora na percepção do zumbido. A pontuação na Escala Visual Analógica (EVA) determinou a divisão dos grupos. Foram aplicados: questionários para avaliar o incômodo do zumbido (Tinnitus Handicap Inventory -THI) e a melhora da percepção auditiva (Hearing Handicap Inventory Elderly Screening Version- HHIE-S); avaliações audiológicas (audiometria de via área e óssea, índice de reconhecimento de fala, identificação do limiar diferencial de intensidade índice, emissões otoacústicas), testes de processamento auditivo temporal (Gaps-in-Noise-GIN, Teste de Detecção de Intervalo Aleatório-RGDT, testes Padrão de Frequência e Duração -TPF e TPD respectivamente) e medidas psicoacústicas do zumbido (pitch, loudness e Limiar Mínimo de Mascaramento - MML) antes da adaptação dos aparelhos auditivos e após dois meses de uso dos aparelhos auditivos. Os sujeitos tinham entre 28 e 68 anos (média 55 anos) de ambos os sexos, e usaram aparelhos auditivos da mesma marca, com as regulagens adequadas para cada sujeito. Resultados: Não houve diferença significativa entre os grupos nos testes audiológicos aplicados. Nos testes auditivos temporais, a porcentagem de acerto do Grupo I foi superior ao Grupo II, com tendência à significância estatística no TPF. Foi observada diferença estatística nos questionários THI, HHIE-S no GI e GII após o uso dos aparelhos, diminuindo a pontuação. Com relação às medidas psicoacústicas, houve diferença estatística significante entre o Loudness e MML iniciais e finais do GI e diferença entre os grupos no loudness e no MML final. Conclusão: As caraterísticas audiológicas avaliadas não foram suficientes para indicar se o paciente com perda de audição se beneficiaria com a diminuição na percepção do zumbido com dois meses de uso de aparelhos auditivos. Indivíduos com desempenho pobre no TPF tem tendência a não reduzir a percepção do zumbido com o uso de aparelhos auditivos. O presente estudo aponta para a necessidade de investigar outras características que podem estar associadas à dificuldade na redução na percepção do zumbido com o uso de aparelhos auditivos / Introduction: Tinnitus is a symptom of damage of the auditory pathways with varied etiology. Many patients with hearing loss have tinnitus and one of its treatments is the use of hearing aids. Hearing aids amplify external sounds and patients are able to better understand the sounds of the environment, reducing the perception of the tinnitus and improving sound input through enriched acoustics. However, according to literature, some patients do not observe discomfort and tinnitus perception decrease using hearing aids. The study of peripheral hearing in these patients could provide information on factors that make it difficult to reduce tinnitus perception with the use of hearing aids. Objective: To evaluate audiological characteristics of patients with tinnitus and hearing loss, and verify if there are differences between the group that obtained reduction in tinnitus perception with the use of hearing aids and the group that did not obtain the same benefit. Methods: 29 subjects, divided into two groups: Group I (GI) composed of 20 subjects who observed improvement in tinnitus perception after two months of hearing aids use and Group II (GII) with nine subjects who did not observe improvement in tinnitus perception, were evaluated. The Visual Analogue Scale (VAS) score determined the division of the groups. The questionnaires Hearing Handicap Inventory Elderly Screening (HHIE-S) and Tinnitus Handicap Inventory (THI), audiological evaluation (pure tone and bone conduction audiometry, speech recognition index, short increment sensitivity index, otoacoustic emissions), temporal auditory processing tests (Gaps-in-Noise-GIN, Random Interval Detection Test-RGDT, frequency and duration tests (PPS and DPT) and psychoacoustic measures of tinnitus (pitch, loudness and MML) before the fitting of hearing aids and after two months of use were conducted. Subjects were aged between 28 and 68 (mean age 55 years), both sexes, and used same brand hearing aids, with the appropriate fitting for each subject. Results: There was no significant difference between the groups in the audiological tests. Temporal auditory tests accuracy percentage of Group I was higher than Group II, with a tendency to statistical significance in the PPS. Statistical difference was observed in the THI, HHIE-S for GI and GII after the hearing aids use, reducing the score. Regarding psychoacoustic measures, there was significant statistical difference between initial and final loudness and MML in GI, and intergroup difference (GI and GII) in the final MML and loudness. Conclusion: The evaluated audiologic characteristics were not sufficient to indicate if the patient with hearing loss would benefit from a decrease in tinnitus perception after two months of hearing aids use. Individuals with poor PPS performance tend not to reduce tinnitus perception with hearing aids use. The present study indicates the need to investigate other characteristics that may be associated with the difficulty in reducing tinnitus perception with hearing aids use

Embora hiper-reatividade auditiva (HRA) e/ou hiperacusia (HPA) sejam manifestações frequentes no Transtorno do Espectro Autista (TEA) são poucos os estudos que investigaram este sintoma com medidas fisiológicas ou exploraram os mecanismos auditivos neurais que podem estar associados a esta característica. O principal objetivo deste trabalho foi estudar a queixa subjetiva (o sintoma) e o desconforto observável (o sinal) da HPA no TEA e avaliar a relação com o efeito inibitório do complexo olivococlear medial (EICOCM). Foram recrutadas 13 crianças e adolescentes com TEA (idade média = 7,2 anos) de ambos os sexos, e 11 crianças e adolescentes com desenvolvimento típico (idade média = 7,2 anos) de ambos os sexos. Para avaliar a HPA, todos os sujeitos responderam a um questionário de caracterização desse sintoma. As medidas psicoacústicas e eletroacústicas permitiram a determinação da sensibilidade auditiva, do funcionamento coclear, do nível de desconforto auditivo e do campo dinâmico da audição. Para a avaliação da via eferente, o EICOCM foi investigado pelas emissões otoacústicas evocadas transientes com ruído contralateral. Os resultados mostraram que o grupo com TEA apresentou desconforto em intensidades mais baixas nas frequências de 1 kHz, 2 kHz e 4 kHz (1 kHz, t = 1,99, p = 0,059; 2 kHz, t = 2,16, p = 0,042; 4 kHz, t = 2,37, p = 0,028), e menor faixa dinâmica auditiva em comparação com o grupo controle, sendo que nas frequências de 0,5 kHz, 4 kHz e 8 kHz houve diferenças estatisticamente significantes (respectivamente: 0,5 kHz p = 0,03; 4 kHz p = 0,01 e 8 kHz p = 0,03). As emissões otoacústicas evocadas transientes evidenciaram amplitudes de resposta coclear semelhante entre os grupos, porém, o efeito inibitório não: o grupo com TEA apresentou valores menores em comparação ao grupo controle (F(4;76) = 3,49, p = 0,01). Houve correlação positiva entre o EICOCM e a medida do campo dinâmico da audição. Crianças e adolescentes com TEA apresentaram maior ocorrência de hiperacusia, o que pode indicar que esse sinal está relacionado a um déficit no EICOCM / Although auditory hyper-responsiveness (AHR) and/or hyperacusis is a frequent manifestation in Autism Spectrum Disorder (ASD), few studies have investigated this symptom with physiological measures or explored the neural auditory mechanisms that may be associated with this characteristic. The main objective was to study the complains (symptom) and the evident discomfort (sign) of hyperacusis in ASD and to evaluate its relationship with the inhibitory effect of the medial olivocochlear bundle (MOCB). Two groups, one of 13 children and adolescents with ASD (mean age = 7.2 years) of both sexes, and other with 11 children and adolescents typically developed (mean age = 7.2 years) of both sexes, were recruited. To assess hyperacusis, all subjects answered a questionnaire characterizing this symptom. The psychoacoustic and electroacoustic measurements allowed the determination of auditory sensitivity, cochlear functioning, level of auditory discomfort and auditory dynamic range. For the evaluation of the efferent pathway, the inhibitory effect of the MOCB was assessed by transient evoked otoacoustic emissions with contralateral noise. The results showed that the group with ASD presented discomfort at lower frequencies in the frequencies of 1, 2 and 4 kHz (1 kHz, t = 1.99, p = 0.059; 2 kHz, t = 2.16, p = 0.042; 4 kHz, t = 2.37, p = 0.028), and lower auditory dynamic range in comparison with the control group, while for the frequencies of 0, 5, 4 and 8 kHz, a statistically significant difference was found (respectively: 0.5 kHz p = 0.03; 4 kHz p = 0.01 and 8 kHz p = 0.03). Transient evoked otoacoustic emissions showed similar cochlear response amplitudes between groups, while the inhibitory effect did not: the group with ASD presented lower values in comparison to the control group (F(4;76) = 3.49, p = 0,01). There was a positive correlation between the inhibitory effect of the MOCB and the auditory dynamic range measurement. Children and adolescents with ASD had a higher occurrence of hyperacusis, which may point out that this sign is associated with a deficit in the inhibitory effect of MOCB

Le système auditif possède deux particularités. En périphérie, les mécanismes cochléaires actifs (MCA), sous-tendus par la motilité des cellules ciliées externes (CCE), interviennent dans la sensibilité auditive et la sélectivité fréquentielle. Sur le versant central, le système efférent olivocochléaire médian (SEOCM), qui se projette sur les CCE et module les MCA, améliore la perception auditive en milieu bruité. Sur le plan exploratoire, ces deux processus peuvent être évalués grâce aux otoémissions acoustiques provoquées (OEAP) et leur suppression controlatérale. Par ailleurs, des résultats expérimentaux chez l’animal ont montré l’existence d’un rétrocontrôle exercé par le système auditif corticofuge descendant (SACD) sur la cochlée, via le SEOCM.Le présent travail comporte trois études réalisées chez l’humain, visant à explorer les interactions entre SACD, SEOCM et MCA. Les études 1 et 2, utilisant une méthodologie innovante chez des patients épileptiques réalisant une stéréo-électroencéphalographie, ont révélé un effet atténuateur différentiel de la stimulation électrique intracérébrale sur l’amplitude des OEAP, en fonction des modalités de stimulation, ainsi qu’une variabilité de cet effet selon les caractéristiques de l’épilepsie. L’étude 3 a montré un renforcement bilatéral de l’activité du SEOCM chez des musiciens professionnels.Pris dans leur ensemble, ces résultats fournissent d’une part, des arguments directs et indirects en faveur de l’existence d’un SACD fonctionnel chez l’humain. D’autre part, des phénomènes de plasticité à long terme, pathologique ou supranormale, seraient susceptibles de modifier l’activité de cette voie cortico-olivocochléaire. / The auditory system has two special features. At peripheral level, active cochlear micromechanisms (ACM), underlain by motility of outer hair cells (OHC), are involved in auditory sensitivity and frequency selectivity. At central level, the medial olivocochlear efferent system (MOCES), which directly projects onto OHC to modulate ACM, improves auditory perception in noise. From an exploratory point of view, both processes can be assessed through transient evoked otoacoustic emissions (TEOAE) and the procedure of contralateral suppression. In addition, experimental data in animals have disclosed a top-down control exerted by corticofugal descending auditory system (CDAS) on cochlea, via MOCES.The present work comprises three studies carried out in human, aiming to investigate interactions between CDAS, MOCES and ACM. The first and second studies, based on an innovative experimental procedure in epileptic patients undergoing presurgical stereoelectroencephalography, have revealed a differential attenuation effect of intracerebral electrical stimulation on TEOAE amplitude depending on stimulation modalities, as well as a variability of this effect depending on the clinical history of epilepsy. The third study has shown a bilateral enhancement of MOCES activity in professional musicians.Taking together, these results provide direct and indirect evidence for the existence of a functional CDAS in humans. Moreover, possible long-term plasticity phenomenon, either pathological –as in epileptic patients– or supernormal –as in professional musicians– may change cortico-olivocochlear activity.