Thesis (Ph. D.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).

Introdução: Crianças com transtorno fonológico (TF) apresentam dificuldade na percepção de fala, em processar estímulos acústicos quando apresentados de forma rápida e em sequência. A percepção dos sons complexos da fala, dependem da integridade no processo de codificação analisado pelo Sistema Nervoso Auditivo. Por meio do Potencial Evocado Auditivo de Tronco Encefálico com estímulo complexo (PEATEc) é possível investigar a representação neural dos sons em níveis corticais e obter informações diretas sobre como a estrutura do som da sílaba falada é codificada no sistema auditivo. Porém, acredita-se que esse potencial sofre interferências tanto de processos bottom-up quanto top-down, o que não se sabe é quanto e como cada um desses processos modifica as respostas do PEATEc. Uma das formas de investigar a real influência dos aspectos top-down e bottom-up nos resultados do PEATEc é estimulando separadamente esses dois processos por meio do treinamento auditivo e da terapia fonoaudiológica. Objetivo: Verificar o impacto da estimulação sensorial (processamento bottom-up) e cognitiva (processamento top-down), separadamente, nos diferentes domínios da resposta eletrofisiológica do PEATEc. Método: Participaram deste estudo 11 crianças diagnosticadas com TF, com idades entre 7 e 10:11, submetidas a avaliação comportamental e eletrofisiológica e então dividas nos grupos Bottom-up (B-U) (N=6) e Top-down T-D (N=5). A estimulação bottom-up foi voltada ao treinamento das habilidades sensoriais, através de softwares de computador. A estimulação top-down foi realizada por meio de tarefas para estimular as habilidades cognitiva por meio do Programa de Estimulação Fonoaudiológica (PEF). Ambas as estimulações foram aplicadas uma vez por semana, num período de aproximadamente 45 minutos por 12 semanas. Resultados: O grupo B-U apresentou melhoras em relação aos domínios onset e harmônicos e no valor da pontuação do escore após ser submetido à estimulação bottom-up. Por sua vez, após serem submetidos à estimulação top-down, o grupo T-D apresentou melhoras em relação aos domínios onset, espectro-temporal, fronteiras do envelope e harmônicos e para os valores da pontuação do escore. Conclusão: Diante dos resultados obtidos neste estudo, foi possível observar que a estimulação sensorial (processamento bottom-up) e a estimulação cognitiva (processamento top-down) mostraram impactar de forma diferente a resposta eletrofisiológica do PEATEc / Introduction: Children with speech sound disorder present difficulties in speech perception specially regarding the processing of acoustic stimuli when they occur rapidly and sequentially. The perception of complex sounds of speech depends on the integrity of the codification process analyzed by the auditory system. Through the Auditory Brainstem Response to complex sounds (cABR) it is possible to investigate the neural representation of sounds in cortical levels to obtain direct information about how the sound structure of the stressed syllable is codified in the auditory system. However, it is believed that bottom-up and top-down processes interfere in the cABR, though the level of intensity and the way through which they can change the response of the cABR is still unkown. One of the methods for investigating the actual influences of the bottom-up and top-down processes in cABR responses is by stimulating separately those two processes by means of auditory training and speech therapy. Objective: Verify the impact of both sensory stimulation (bottom-up processing) and cognitive stimulation (top-down processing) separately, in the different domains of the cABR electrophysiological response. Method: The participants of the study were 11 children of 7 to 10:11 year-old diagnosed with speech sound disorder, who underwent behavioral and electrophysiological assessment and were divided in the following groups: Bottom-up (B-U) (N=6) and Top-down (T-D) (N-5). The bottom-up stimulation focused on sensorial skills by using computer softwares. Top-down stimulation was prosecuted by using tasks to stimulate cognitive skills through the Speech Stimulation Program. Both stimuli were applied once a week for 45 minutes, in a period of 12 weeks. Results: The B-U group showed improvement in relation to onset and harmonic domains, and in relation to the score punctuation values after being subjected to bottom-up stimulation. On the other hand, the T-D group, after being subjected to top-down stimulation, showed improvement in relation to the onset, time domain spectrum, envelope boundaries and harmonics, and to the score punctuation values. Conclusions: According to the results of this study, it was possible to conclude that sensorial stimulation (bottom-up processing) and cognitive stimulation (top-down processing) showed different impacts on the cABR electrophysiological response

Slow-wave sleep plays an important role in consolidation of declarative memory. From electrophysiological point of view, this process is dependent on a common occurrence and mutual integration of neocortical slow oscillations (< 1 Hz), hippocampal sharp-wave ripples (150-250 Hz) and thalamo-cortical sleep spindles (10-15 Hz). Previous studies demonstrated that periodic acoustic stimulation by pink noise pulses applied at frequency of sleep slow oscillation during slow wave sleep leads to prolongation of slow wave sleep and to enhancement in declarative memory performance in normal sleepers. Our study investigated this kind of periodic acoustic stimulation in its relation to sleep architecture and declarative memory of people suffering from insomnia due to which there often comes to a reduction in slow wave sleep which positively correlates with worsening of declarative memory performance. Our aim was to investigate if this kind of comparatively non-invasive brain stimulation has a potential to increase a total length of slow wave sleep and enhance declarative memory performance in insomnia. Our study revealed acoustic stimulation neither improved declarative memory performance nor it increased total length of slow-wave sleep. No positive association was found between level of declarative memory...

OBJECTIVE: To determine in an interrupted word paradigm (Maryland CNCs; 10 ips, 50% duty cycle) if different locations of the interruption pattern produce different recognition performances. DESIGN: Repeated measures using two interruption patterns that were complementary halves referenced to word onset; one started with word onset (0-ms), the other started 50 ms later. The hypothesis was that recognition performance would be better on the 0-ms condition than on the 50-ms condition, but there would be some words with the reverse relation. STUDY SAMPLE: Twenty-four young adults with normal hearing for pure tones and 32 older adults (mean = 67 years) with sensorineural hearing loss participated. RESULTS: With the young listeners mean recognition performance on the 0-ms condition (63.1%) was significantly better than the mean performance on the 50-ms condition (47.8%). About twice as many words had better performance on the 0-ms condition. With the older listeners, who were given only stimuli on which performances were > 58% by the young normals, performances on the two conditions were the same. CONCLUSIONS: The hypothesis was supported with the young listeners. The equal performance by the older listeners on the two conditions was attributed to the manner in which the words were selected.