Previous studies have found that spatial processing in children and adults with Down syndrome is different in comparison to the normal population. Some previous studies have also found that there is a high prevalence of colour vision deficiencies in people with Down syndrome. The aim of the present study was to use an objective test, the transient visual evoked potential (VEP), to assess achromatic and chromatic visual processing in adults with Down syndrome. Achromatic VEPs were recorded in response to black-white stimuli presented in patternreversal mode. Chromatic VEPs were recorded in response to two types of colour pattern, presented in pattern onset-offset mode. The two colour types were intended to preferentially stimulate the two principal chromatic pathways of the visual system, the ???redgreen??? and ???blue-yellow??? colour-opponent pathways. These stimuli are here termed the ???LM??? and ???S-(L+M) stimuli, respectively, reflecting the cone types that input to the pathways they are intended to stimulate. Each subject also completed two subjective colour vision tests, the Colour Vision Test Made Easy (CVTME) and the City University Colour Vision Test (CUT). Morphology of the achromatic and chromatic VEPs was found to differ between the group with Down syndrome and an age-matched control group. The latency of the P100 component of the achromatic VEP was found to be significantly later in the group with Down syndrome compared to the control group (the N75 latency was earlier in the group with Down syndrome, but not significantly so). The group-averaged peak-to-peak amplitude of the achromatic VEP was significantly lower in the group with Down syndrome compared to the control group. The major positive component of the VEP in response to the L-M stimulus was of significantly longer latency compared to that of the control group. The major negative component and the peak-to-peak amplitude of this response were not significantly different between the groups. For the response to S-(L+M) stimuli, the latency of the major negativity was significantly earlier in the group with Down syndrome and the major positivity was later, but not significantly so. Amplitude of this response was significantly higher in adults with Down syndrome compared to the control group. Most subjects in both groups passed both the CVTME and CUT. Our findings indicate that chromatic VEPs are abnormal in Down syndrome, and this may reflect abnormal processing of chromatic stimuli in this population. Alternatively, these abnormalities may arise due to abnormal cortical morphology, which may occur with normal or abnormal processing of chromatic signals. These findings further indicate that abnormality of chromatic VEPs may be expected in Down syndrome, and is not necessarily indicative of pathology or other abnormal function that is unrelated to the syndrome.

Thesis (M.A.)--University of Nevada, Reno, 2007. / "August, 2007." Includes bibliographical references (leaves 10-11). Online version available on the World Wide Web.

Thesis (Au. D.)--Missouri State University, 2008. / "May 2008." Includes bibliographical references (leaves 49-53). Also available online.

Thesis (M. Aud.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

Thesis--University of Jyväskylä, 1997. / Added t.p. with thesis statement inserted.

Thesis (M. Sc.)--University of Hong Kong, 1998. / Includes bibliographical references (leaf 88-91).

Thesis--University of Jyväskylä, 1997. / Added t.p. with thesis statement inserted.

Thesis (M.Sc.)--York University, 2005. Graduate Programme in Kinesiology and Health Science. / Typescript. Includes bibliographical references (leaves 72-82). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11836

Thesis (PhD) - Swinburne University of Technology, Brain Sciences Institute, 2008. / A thesis submitted for the degree of Doctorate of Philosophy, Brain Sciences Institute, Swinburne University of Technology - 2008. Typescript. Includes bibliographical references (p. 98-133)

Introdução: A captação e o estudo de respostas cerebrais evocadas por um estímulo sonoro vem permitindo a investigação objetiva do processamento da informação auditiva e uma melhor compreensão da via auditiva central. A utilidade deste método diagnóstico tem sido cada vez mais valorizada pelos audiologistas, no entanto sua aplicação clínica corrente requer a realização de uma quantidade mais expressiva de estudos, especialmente na literatura nacional, para um conhecimento mais profundo deste método, sobretudo quanto a normatizações, critérios de identificação das ondas e interferências de variáveis como idade, sexo e parâmetros utilizados na aquisição. Os Potenciais Evocados Auditivos de Média Latência são compostos por uma seqüência de ondas com latências em torno de 10 a 80ms, com origem neurogênica múltipla (projeções tálamo-corticais e córtex auditivo, colículo inferior e formação reticular em menor escala). O presente estudo tem como objetivo pesquisar os componentes dos PEAMLs, numa população de crianças saudáveis, estudando a latência e amplitude das ondas, a fim de conhecer as características dos PEAMLs para esta faixa etária. Metodologia: Participaram do estudo 32 crianças de ambos os sexos com idade entre 10 e 13 anos, otologicamente normais e sem histórias neurológicas. A análise estatística incluiu a realização da estatística descritiva (média e desvio-padrão) e análise da variância pelo teste F. Os PEAMLs foram pesquisados utilizando como estímulo tone-burst, nas intensidades de 50, 60 e 70 dBNA. Resultados e conclusão: Os valores médios de latência dos componentes foram Na=20,79ms, Pa=35,34ms, Nb=43,27ms e Pb=53,36ms. Para a amplitude Na-Pa os valores médios obtidos no estudo variaram entre 0,2 e 1,9mV (M=1,0mV). As formas de onda Na-Pa constituíram os componentes mais consistentes e mais facilmente identificáveis. Pode-se concluir que a amplitude aumenta e a latência diminui com o aumento da intensidade sonora. Na intensidade de 50dBNA as latências obtidas são significativamente maiores que as intensidades de 60 e 70 dBNA para a onda Na. A partir de 60dBNA os valores se estabilizam e não há mudanças significativas na latência ou morfologia da onda. Nas comparações inter e intra-individual foram observadas latências mais longas e amplitudes menores para o lado E (A1/Cz). Numa análise posterior dos dados segundo queixa de dificuldade escolar não foram observadas diferenças ao nível de significância para os componentes Na, Pa, Nb e Pb para os grupos de crianças com e sem queixa de dificuldades escolares. Nestas crianças foram observadas anormalidades na morfologia das ondas, as quais não foram atribuídas exclusivamente à queixa de dificuldade escolar, já que poderia haver também interferência da idade do sujeito avaliado e do neuro-desenvolvimento do Sistema Nervoso Auditivo Central. O presente estudo possibilitou um melhor conhecimento das características dos PEAMLs, o que contribuirá para a aplicação mais segura da técnica. Porém, outros estudos ainda se fazem necessários, principalmente na literatura nacional, a fim de estabelecer padrões normativos para o uso na rotina clínica. / Introduction: The record and study of corticals responses evoked by auditory stimulus has allowed the objective investigation from process of auditory information and a better understanding of central auditory path. The utility of the procedure has been valued by audiologists, nevertheless her clinical aplication current demand the a execution a sum more significative of the study, especially in nationals researchs, to knowledge profoundest this procedure, over all as for normative studys, waves?s identification criterion and interference of the variables with age, gender and parameters used in records. The PEAMLs are composed of a waves?s sequence with latency are around 10 a 80ms, with multiple neurogenic origen (thalamus corticais projections and auditory cortex, coliculus inferior and reticular formation in small scale). The present study objetive examined the components dos PEAMLs, in healthy childrens, researching the waves?s latency and amplitude, to know the PEAML in this band of age. Methods: make part of study 32 childrens in both genders between the ages of 10 e 13, normal hearing without neurological desorders. The statistical analises involved the descrition statistical (mean and standard deviation) and variance analises by test F. The PEAMLs are investigated with tone-burst stimuli in 50, 60 e 70 dBNA. Results and conclusions: the means values of the components are Na=20,79ms, Pa=35,34ms, Nb=43,27ms e Pb=53,36ms. To the amplitude Na-Pa the means values obtained in the study varies between 0,2 and 1,9mV (M=1,0mV). The waveforms are more consistents e more easyly identifiable. We are able to conclude that the amplitude increase and latency decrease with growth of intensity of sound. In 50dBNA the latency are significative higher that 60 and 70 dBNA to wave Na. From 60dBNA the values are stabilize and there is no significatives changes in the latency ou morphology of wave. In the comparisions inter e inta-hemisferical were observed latencys lengthest and amplitudes higher to side left (A1/Cz). In a posterior analises in conformity to complaint of hardness scholar were observeds diferrences no significants to the components Na, Pa, Nb e Pb in the childrens groups with and without complaint of hardness scholar. Anormalities in the morphology of waves were viewed in this childrens wich weren´t atribute to complaint of hardness scholar exclusively once there was interference of the patient?s age and the neural development of Central Auditory System Nervous. The present study made possible a better knowledge of PEAMLs and will contribute to securest aplication this procedure. But, another studys still are requisite, essentialy in the researchs national to established normatives standard to utily in the clinical practice.