Nos recherches ont porté sur l'étude des indices d'orientation (sonores et verbaux) de l'attention auditive dans une situation d'écoute dichotique au cours du développement. Quatre expériences ont été proposées à des enfants âgés de 8 à 12 ans ainsi qu'à des adultes. Si les deux types d'indices permettent aux populations adultes d'orienter efficacement leur attention vers leurs deux oreilles pour identifier les stimuli cibles et pour résoudre les conflits cognitifs induits par les conditions d'orientation, en revanche, seuls les enfants de plus de 9 ans utilisent les indices verbaux pour orienter efficacement leur attention et résoudre les conflits cognitifs. L'ensemble des résultats suggère (a) que les capacités d'orientation de l'attention se développent en synergie avec le développement cérébral (maturation du cortex préfrontal qui connait une accélération vers 9 ans) et (b) que des indices verbaux favorisent une orientation efficace de l'attention des enfants de moins de 9 ans ainsi que des performances élevées d'identification des stimuli dans leurs deux oreilles. Nous avançons l'hypothèse selon laquelle le rôle facilitateur des indices verbaux résulterait de la pré-activation des processus top-down qu'ils suscitent. En effet, les processus top-down s'avèrent être nécessaires à un contrôle attentionnel de qualité. Ainsi, la présentation de ces indices favoriserait l'activation de ces processus, qui sont difficilement sollicités par les jeunes enfants. L'immaturité du cortex pré-frontal des enfants de moins de 9 ans pourrait expliquer les difficultés d'activation spontanée. / Our work focused on the study of auditory orienting attention cues (with tone cues and verbal cues) in dichotic listening situations across development. Four experiments were carried out with 8 to 12 years old children and with adults. If adults appeared to benefit from the use of tone cues as much as the use of verbal cues to improve their performance of identification in both ears, and thus to improve their cognitive control, however, only 9 years old children took advantage of verbal cues to orient more efficiently their attention and resolve cognitive conflicts. Below this age, only tones cues helped the children to orient and control their attention to the indicated ear.Altogether our results reveal that (a) auditory orienting capacities develop in synergy with cerebral development (the maturation of the prefrontal cortex increases at around 9 years of age), and that (b) verbal cues lead to an efficient orientation of attention and high performance of identification in both ears, even under the age of 9.We suggest that the facilitator role of verbal cues could result from the pre-activation of the top-down processes that they involve. Indeed, top-down processes are essential for cognitive control. Therefore, the presentation of this type of cues would enhance the activation of processes that are not so easily recruited by young children. The immaturity of the pre-frontal cortex of children below 9 years of age could explain the difficulties encountered by this age group.

Realizou-se um inventário quantitativo e qualitativo das características demográficas e dos erros cometidos nos itens dicóticos do Teste de Dissílabos Dicóticos Alternados, também conhecido como SSW em português, com as informações de 722 sujeitos que completaram este teste nos anos de 1994 a 2001. Os resultados revelaram que a amostra estudada foi composta em sua maioria de sujeitos do sexo masculino, cursando as séries iniciais do ensino fundamental, relatando dificuldades de fala, escria e leitura e neurologicamente normais, com desordem de processamento auditivo do tipo decodificação, de grau leve/moderado. Uma tendência de erro em alguns itens dicóticos do teste foi observada. / A total of 722 subjects provided the information for the quantitative and qualitative inventory of demographic features and the errors observed in the dichotic items of the Portuguese version of the SSW Test. Results revealed that, collectively, these subjects were mostly males, in elementary school, referring speech, reading and writing difficulties, and not presenting neurological disorders. They also presented a decoding-type auditory processing disorder of mild/moderate severity. Error and performance profiles were characterized by multivariate statistics.

Central auditory processing is complex and can not be evaluated by a single method. This thesis focuses on assessment of some aspects of central auditory functions by the use of dichotic speech tests and cognitive tests that tax functions important for speech processing. Paper A deals with the cognitive effects in dichotic speech testing in elderly hearing-impaired subjects. It was found that different listening tasks in the dichotic tests put different demands on cognitive ability, shown by a varying degree of correlation between cognitive functions and dichotic test parameters. Age-related cognitive decline was strongly connected with problems to perceive stimuli presented to the left ear. Paper B presents a new cognitive test battery sensitive for functions important for speech processing and understanding, performed in text, auditory and audiovisual modalities. The test battery was evaluated in four groups, differing in age and hearing status, and has proven to be useful in assessing the relative contribution of different input-modalities and the effect of age, hearingimpairment and visual contribution on functions important for speech processing. In Paper C the test battery developed in Paper B was used to study listening situations with different kinds of background noise. Interfering noise at +10 dB signal-to-noise ratio has significant negative effects on performance in speech processing tasks and on the effort perceived. Hearing-impaired subjects showed poorer results in noise with temporal variations, and elderly subjects were more distracted by noise with temporal variations, especially by noise with meaningful content. In noise, all subjects, particularly those with impaired hearing, were more dependent upon visual cues than in the quiet condition. Hearing aid benefit in speech processing with and without background noise was studied in Paper D. The test battery developed in Paper B was used together with a standard measure of speech recognition. With hearing aids, speech recognition was improved in the background condition without noise and in the background condition of ordinary speech. Significantly less effort was perceived in the cognitive tests when hearing aids were used, although only minor benefits of hearing aid amplification were seen. This underlines the importance of considering perceived effort as a dimension when evaluating hearing aid benefit, in further research as well as in clinical practice. The results from the studies contribute to the knowledge about speech processing but also to the search for more specific evaluation of speech understanding, incorporating both sensory and cognitive factors. / The ISBN 91-85297-49-6 in the printed verison is incorrect. The correct ISBN is 91-85297-93-3.

Realizou-se um inventário quantitativo e qualitativo das características demográficas e dos erros cometidos nos itens dicóticos do Teste de Dissílabos Dicóticos Alternados, também conhecido como SSW em português, com as informações de 722 sujeitos que completaram este teste nos anos de 1994 a 2001. Os resultados revelaram que a amostra estudada foi composta em sua maioria de sujeitos do sexo masculino, cursando as séries iniciais do ensino fundamental, relatando dificuldades de fala, escria e leitura e neurologicamente normais, com desordem de processamento auditivo do tipo decodificação, de grau leve/moderado. Uma tendência de erro em alguns itens dicóticos do teste foi observada. / A total of 722 subjects provided the information for the quantitative and qualitative inventory of demographic features and the errors observed in the dichotic items of the Portuguese version of the SSW Test. Results revealed that, collectively, these subjects were mostly males, in elementary school, referring speech, reading and writing difficulties, and not presenting neurological disorders. They also presented a decoding-type auditory processing disorder of mild/moderate severity. Error and performance profiles were characterized by multivariate statistics.

Responses of 122 children were obtained on two measures of central auditory processing to establish normative data. Children aged 6.5 through 12.5 years were tested for humming and tapping responses to the Pitch Pattern Sequence Test (PPST) and the two- and four-digit Dichotic Digit Tests (DDT). Children between ages 6.5 and 9.5 years showed progressively better scores on the tapping response of the PPST and on the four-digit DDT. Children above 9.5 years of age demonstrated adult-like responses on both tests. No differences were demonstrated in performance of children aged 6.5 through 12.5 years on the two-digit DDT or on the humming response of the PPST.

No description available.

<p>Rolandic epilepsy (RE) is the most common focal epilepsy syndrome in the pediatric age group with an onset between 3 and 13 years. The syndrome is defined by electro-clinically typical features and has been considered benign according to seizure remission before the age of 16 years.</p><p>The aim of this thesis was to investigate children with typical RE with different methods and to discuss the delineation of the syndrome. Thirty-eight children, aged 6–14 years, participated in one up to four studies.</p><p>Eighteen children were investigated with MRI. Hippocampal abnormalities were found in six (33%), volume asymmetry in five (28%) and high signal intensities on T2-weighted images in three (17%). Additionally, high signal intensities in T2-weighted images were revealed subcortically in temporal and frontal lobes bilaterally in five children (28%).</p><p>The hippocampal region was evaluated metabolically using proton magnetic resonance spectroscopy (¹H-MRS) in 13 children with RE and 15 matched controls. A metabolic asymmetry of the hippocampal regions was found in the patients compared to controls indicating an abnormal neuronal function.</p><p>Seventeen children with RE and 17 matched controls were investigated with a neuropsychological test battery. The RE children showed lower performance in auditory-verbal tests and in executive functions compared to controls.</p><p>Twenty RE children and 24 controls were assessed concerning their oromotor function. The RE children had greater problems concerning tongue movements including articulation. A dichotic listening test was also performed in a subgroup showing poorer results in the RE group. </p><p>A simple classification is proposed with RE ‘pure’ as the main group and the frame for this study.</p><p>In conclusion, these investigations disclosed various abnormalities in children with RE, challenging the benign concept during the active phase. It is assumed that maturational factors comprise causal mechanism to the deviant findings, which probably successively will normalize.</p>

Rolandic epilepsy (RE) is the most common focal epilepsy syndrome in the pediatric age group with an onset between 3 and 13 years. The syndrome is defined by electro-clinically typical features and has been considered benign according to seizure remission before the age of 16 years. The aim of this thesis was to investigate children with typical RE with different methods and to discuss the delineation of the syndrome. Thirty-eight children, aged 6–14 years, participated in one up to four studies. Eighteen children were investigated with MRI. Hippocampal abnormalities were found in six (33%), volume asymmetry in five (28%) and high signal intensities on T2-weighted images in three (17%). Additionally, high signal intensities in T2-weighted images were revealed subcortically in temporal and frontal lobes bilaterally in five children (28%). The hippocampal region was evaluated metabolically using proton magnetic resonance spectroscopy (1H-MRS) in 13 children with RE and 15 matched controls. A metabolic asymmetry of the hippocampal regions was found in the patients compared to controls indicating an abnormal neuronal function. Seventeen children with RE and 17 matched controls were investigated with a neuropsychological test battery. The RE children showed lower performance in auditory-verbal tests and in executive functions compared to controls. Twenty RE children and 24 controls were assessed concerning their oromotor function. The RE children had greater problems concerning tongue movements including articulation. A dichotic listening test was also performed in a subgroup showing poorer results in the RE group. A simple classification is proposed with RE ‘pure’ as the main group and the frame for this study. In conclusion, these investigations disclosed various abnormalities in children with RE, challenging the benign concept during the active phase. It is assumed that maturational factors comprise causal mechanism to the deviant findings, which probably successively will normalize.

Le processus du traitement de la parole est latéralisé au niveau cortical. En effet la théorie de l’échantillonnage asymétrique suggère que le signal acoustique est segmenté sous forme d’unités discrètes, et ensuite traité par les deux cortex auditifs non primaires en utilisant des fenêtres d’intégrations respectivement adaptées aux traitements des modulations lentes et rapides du signal de la parole. L’objectif de cette thèse était d’étudier les concepts de cette théorie au moyen de deux approches (psychophysique et neurophysiologique), en s’intéressant à l’activation corticale dans les deux hémisphères en fonction de la nature du signal auditif présenté. Les résultats révèlent que les scores d’intelligibilité de ces stimuli sont plus importants quand les modulations rapides arrivent au cortex auditif gauche et les modulations lentes arrivent au cortex auditif droit. Les résultats de l’IRMf démontrent une interaction entre l’enveloppe des stimuli présentés et les rythmes corticaux. Les deux cortex auditifs présentaient des asymétries inter-hémisphériques en réponse à ces stimuli. En outre, l’activité neuronale augmente avec les performances. Dans l'ensemble, les résultats de nos études vont dans le sens des prédictions de la théorie d’échantillonnage asymétrique. Nous supposons que, l’application des effets de la théorie de la latéralisation auditive dans le traitement du signal auditif pourrait améliorer la perception de la parole chez les personnes sourdes profonds en développant les stratégies de codage des Implants cochléaire de manière à les alignées sur les propriétés corticales d’échantillonnages intrinsèques / Speech perception consists of a set of bilateral computations that take continuously varying acoustic waveforms as input and generate discrete representations. Hypothesis of ‘asymmetric sampling in time’, suggests that auditory functional asymmetries can be explained by differences in temporal sampling between the two auditory cortices. We suggest that asymmetry in auditory cortical oscillations could play a role in speech perception by fostering hemispheric triage of information across the two hemispheres. Due to this asymmetry, fast speech temporal modulations, could be best perceived by the left auditory cortex, while slower modulations would be better captured by the right one. The aim of this thesis was to study and to test the validity of the predictions of the AST theory by investigating psychophysical and neurophysiological approach. They focus on the cortical activation in both hemispheres according to the nature of the auditory signal presented to both ears. Our results show that when we provide a different part of the speech envelope to each ear, word recognition is facilitated when the temporal properties of speech match the rhythmic properties of auditory cortices. We further show that the interaction between speech envelope and auditory cortices rhythms translates in their level of neural activity (as measured with fMRI). In the left auditory cortex, the neural activity level related to stimulus/brain rhythm interaction predicts speech perception facilitation. This interaction impacts speech perception performance. We propose that this lateralization effect could have practical implications in the framework of bilateral cochlear implants

The purpose of this study is to show that instructional methods designed for right-brained students will make a significant difference in the reading achievement scores of the students when compared with the scores of right-brained sixth grade students not receiving these instructional methods.The subjects were sixth grade students who use the right hemisphere of the brain to a greater degree than the left hemisphere. The subjects' cerebral preference was determined by a test known as the Cerebral Preference Index (CPI). Ten students each were chosen from two sixth grade classes. The study consisted of a Control Group and Experimental Group. During the study the Control Group received eight weeks of the regular school's program while the Experimental Group received eight weeks of instructional strategies that take hemispheric specialization into consideration. The results indicated that there was no significant difference in the reading achievement scores of those students who received the instructional methods designed for right brained students. The analysis of data did suggest that those scoring high on the pre-test scored high on the post test. The results indicated the same outcome for low scorers.