Orientador: Edi Lucia Sartorato / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-05T05:26:35Z (GMT). No. of bitstreams: 1 Christiani_ThalitaVitachi_M.pdf: 7416540 bytes, checksum: e3a8d9e21a7e00adc8a3661b08d564c3 (MD5) Previous issue date: 2005 / Resumo: A forma mais comum de surdez não-sindrômica com padrão de herança autossômico recessivo é causada por mutações no gene GJB2 (que codifica a proteína conexina 26). Recentemente duas deleções que interrompem o gene GJB6 (que codifica a proteína conexina 30), próximo ao gene GJB2, chamadas del(GJB6-D13S1830) e del(GJB6-D13S1854) foram descritas na presença de mutações in trans no outro alelo do gene GJB2. Dentre todas as mutações descritas até o momento, a mutação 35delG no gene GJB2 é a mais comum e é encontrada praticamente em todas as populações estudadas. Dados preliminares sugerem que as alterações causadas devido a mutações no gene GJB2 não afetam as células do gânglio espiral, as quais constituem o principal alvo de estimulação do implante coclear. Além disso, acredita-se que a sobrevida das células do gânglio espiral é fator determinante ao sucesso do implante. Desta forma, foram estudados 115 pacientes candidatos ou submetidos ao implante coclear com perda auditiva não-sindrômica de etiologia não esclarecida a fim de se determinar à prevalência de mutações nos genes GJB2 e GJB6, assim como mutações em genes mitocondriais 12S rRNA e tRNASer(UCN) em pacientes candidatos e submetidos ao implante coclear. Como resultado foram encontrados 42,85% de indivíduos com mutações, incluindo duas novas alterações no gene GJB2 ambas em heterozigose (W172X e K168R), um paciente homozigoto para a del(GJB6-D13S1830), e um paciente com a mutação mitocondrial A1555G. Concluindo, esses resultados estabelecem que o rastrearnento genético proporciona o diagnóstico etiológico, importante para o aconselhamento genético podendo fornecer um melhor prognóstico para o implante coclear, como sugerido em estudos prévios / Abstract: The most common form of non-syndromic autosomal recessive deafness is caused by mutations in the GJB2 gene which encodes connexin 26. Among all the mutations described to date in the GJB2 gene, is the most common and has been found in virtually of the populations studied. Preliminary data suggest that pathologic changes due to GJB2 mutations do not affect the spiral ganglion cells, which are the site of stimulation of the cochlear implant. Besides, the survival of the spiral ganglion cells is believed to be an important determinant of the outcome after surgery. Recently, two deletions truncating the GJB6 gene which encodes connexin 30, near GJB2, named deI (GJB6D13S1830) and del(GJB6-D13S1854) have also been frequently described accompanying in trans mutations in another allele ofthe GJB2 gene.Therefore, we have studied 115 nonsyndromic deaf patients with unlrnown etiologies in order to determine the prevalence of the GJB2 and GJB6 gene mutations as well as mutations in the mitochondrial genes 12S rRNA e tRNASer(UCN) in patients undergoing cochlear implantation surgery. As a result, we found 42,85% of the individuais with mutations including two new mutations in the gene GJB2 (W172X and KI68R), one patient homozygous for the ..1(GJB6-D13S1830) mutation, and one patient with the mitochondrial mutation A1555G. Concluding, these results establish that genetic screening can provi de an etiologic diagnosis, which highlights a counseling importance, and may provide a prognostic on performance after cochlear implantation, as has been hypothesized in previous studies / Mestrado / Biologia Celular / Mestre em Biologia Celular e Estrutural

Cochlear implants are a recognised treatment for severe and profound hearing losses, and can greatly improve speech discrimination in a quiet listening environment. However, poor specificity of neural excitation resulting from wide current spread within the cochlea leads to inadequate complex pitch perception, affecting speech discrimination in noisy environments and music perception. Tripolar is a stimulation mode with a greater degree of current focusing than the monopolar mode currently used in the clinic. The overall aim of the experiments in this thesis was to evaluate the potential of tripolar stimulation mode to improve complex pitch perception compared to monopolar stimulation mode in a group of Advanced Bionics cochlear implant listeners. First, the place specificity of tripolar and monopolar stimulation was compared using a psychophysical forward masking task with a dual-electrode masking stimulus to limit off-site listening. An overall improvement in the place specificity of tripolar compared to monopolar stimulation indicated that current focusing may provide more independent transmission of temporal information from different electrode places. This conclusion was unaffected by the degree of residual masking which, although measurable, was similar in both modes. Second, the effect of current focusing on delivery of independent temporal patterns was evaluated, specifically whether transmission of fine temporal information about interpulse intervals was improved using tripolar over monopolar stimulation. No advantage was found for current focusing in the delivery of temporal patterns on either a single electrode site, or across-electrodes. Third, the effect of mode on complex pitch perception was investigated by comparing a tripolar with a monopolar listening program. Results showed no improvement in pitch ranking ability from current focusing using sung vowel stimuli, and further suggested that a cue related to the centroid of excitation was providing a stronger cue to pitch than the temporal modulations available in both modes in this group. In conclusion, tripolar stimulation, on average, improved place specificity using forward masking, but not temporal cues to pitch using the methods chosen to evaluate this. Furthermore, current focusing did not improve the ability to rank sung vowels based on pitch over monopolar mode. Current focusing, therefore, was not found to enhance perception of complex harmonic pitch in this group. However, a degree of inter-participant variability in amount of benefit from current focusing observed in this series of experiments suggests that it may be useful for some cochlear implant listeners if a predictive measure of benefit were developed.

In most classrooms, where information is presented orally via spoken language, accurate knowledge of a student's hearing status is crucial so that the interdisciplinary team can ensure appropriate service provision. Audiologists play a key role on the interdisciplinary team to provide other professionals with information about children's hearing status, communication needs, device use, and intervention strategies. Conversely, audiologists gain valuable information and strategies from other team members.

A great deal of evidence suggests that parental communication and involvement are essential for the development of language in young children. However, hearing parents of deaf children face unique challenges in providing appropriate stimulation and language input to their deaf children. To date, few studies have determined which types of input are best. This study utilized data collected from the largest, youngest, nationally representative sample of deaf children receiving cochlear implants. The purpose of this study was to identify the facilitative language techniques that are most effective in facilitating receptive and expressive language development in young deaf children. Ninety-three deaf children, ages 2 years and under were enrolled at six implant centers. Deaf children were assessed prior to implantation and then followed for three years post-implantation. At each assessment, parent-child interactions were videotaped in an unstructured Free Play and structured Art Gallery task. All parent and child speech, vocalizations, and sign language were transcribed from the 10 minute videotaped parent-child interactions and coded using the Parenting Strategies for Communication coding system. Results revealed that the most frequently used lower-level strategies used by parents were directives, comments, and close-ended questions. The most frequently used higher-level strategies were parallel talk, open-ended questions, and recast. In addition, the Art Gallery task facilitated more parent utterances and longer mean length of utterances compared to Free Play, but the frequency of facilitative language techniques was not different. Using bivariate latent difference score modeling, higher-level strategies predicted growth in expressive language scores across three years post-implantation. Further, higher-level strategies had a delayed effect on receptive language, with techniques used at 24 months post-implantation predicting growth in receptive language at 36 months post-implantation. These results suggested that parent's play an active role in facilitating their child's language development. Interventions for parents should be developed using a coaching model, where parents receive hands-on training and practice using these effective facilitative language techniques. Future studies should evaluate the effectiveness of this intervention, as well as the effectives of these language techniques in children implanted after 2 years of age.

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