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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Event-related potentials as a form of neurofeedback using low-cost hardware

Jacoby, James Derek 31 August 2016 (has links)
The studies reported in this dissertation demonstrate that low-cost hardware is capable of detecting neural responses to stimuli in the user’s focus of attention, and that these responses increase in magnitude with training. Neurofeedback is a sub-category of biofeedback that is concerned with using brain signals as the source of training data in a feedback loop. The neurofeedback training procedures in this dissertation focused on the P300 component, a time-locked event-related potential (ERP) that reflects the cognitive processes of attention and context updating. The current work provides preliminary evidence that neurofeedback based on rewarding a P300-like ERP is effective in increasing the magnitude of this response. Three main questions were examined: 1. Is the Emotiv Epoc, as an example of a low-cost consumer EEG, capable of reliably detecting the P300 component? 2. Is there a training effect whereby the P300 response gets stronger with practice? 3. To what extent is the P300 response affected by cognitive factors such as memory load and self-generation of prompts? The studies employed an open source software framework—open source tools provide a transparent, crowd-supported means of conducting research, but are often difficult to initially use and the current dissertation provides a guide within this content domain. The Emotiv Epoc headset was capable of detecting P300-like ERP in a P3 speller task. The P3 speller is a well-studied paradigm in which users spell letters using only their thoughts as input, while the system determines the letter to be spelled by analyzing the strength and timing of the ERP. Although the analyzed ERP behaved functionally like a P300, and the timing was consistent, the spatial localization of the signal was more frontally dominant than a standard P300. In the training study, 12 participants completed five P3 spelling sessions. Although an ERP training effect was observed, participant motivation and fatigue modulated this effect. In an attempt to improve motivation and increase interest in the task, a novel card game task was introduced. In this task—a variant of the card game “Concentration,” where players turn cards face-up one at a time to match pairs—the participants used an attentional mechanism to select cards. This allowed for attentional training while offering a task whereby cognitive difficulty could be manipulated. In these studies, the P300-like ERP proved itself to be robust in regards to changes in cognitive difficulty, as well as internal versus external generation of prompts. This led to confidence in the separation of underlying cognitive and attentional processes and validated the focus of the P300 ERP on the attentional process. The results indicated that ERP-specific neurofeedback is effective in increasing ERP magnitude. This dissertation does not involve any clinical populations as study participants, but the long-term potential of this research is to directly train a brain response relevant to clinical conditions. The paradigm can be implemented using low-cost hardware as opposed to research-grade instruments, which increases the likelihood of further research by the clinical community and lowers the barrier of entry for future exploration of the techniques. / Graduate / 0633 / derekja@uvic.ca
2

Hacktivism and the heterogeneity of resistance in digital cultures

Micali, Alberto January 2016 (has links)
Digital media and networks occupy an increasing central position within contemporary societies. This position does not simply involve communicational forms. From the turn of the millennium, phenomena of on- line activism have regularly emerged, bringing novel political forms of resistance to the fore. In academic literature, such phenomena are defined as ‘hacktivism’, putting hacker culture in contact with the politically motivated use of networked media by social movements. However, these scholarly perspectives often fail to deal sufficiently with the original forms of mediation that are at stake in hacktivist ‘deployments’ of media apparatuses. Finding inspiration especially in the work of Félix Guattari, I propose a ‘machinic’ methodology able to deal with the relations and processes with which the act of researching is inescapably involved, overcoming the distances that epistemologically separate the subject from its objects of research. Hence, I originate a ‘method assemblage’ by combining emergent theories in the field of media and culture, and advancing a critical questioning on the same researching procedures. Linking media ecologies and archaeologies, the resulting creative method allows an approach to the case study of ‘Anonymous’ through a novel critical compass. The original creation of the method aims to study without foreclosing the heterogeneous forms of active resistance actualised through media technologies. I suggest that the short-term, transient character of contemporary forms of resistance does not lack political efficacy. Rather hacktivism has to be reconsidered in vital terms beyond representation, within a field that is ‘micro-political’ and materially involves novel processes of subjectivation and disruptiveness.
3

How does technological development and adoption occur in the media? : a cultural determinist model

Winston, Brian Norman January 2006 (has links)
The thesis hereby submitted, ‘How Does Technological Development And Adoption Occur In The Media? A Cultural Determinist Model’ was originally published in Media Technology and Society A History: from the telegraph to the Internet (London: Routledge 1998) and Technologies of Seeing: Photography, Cinematography and Television (London: British Film Institute 1996). The argument outlined in those two books is further supported and updated by six other texts published between 1995 and 2005 on the same topic. Media Technology and Society A History: from the telegraph to the Internet deals with the development of electrical and electronic mass media proposing a model for the nature of such developments. It is a final iteration of an approach to this history which has its origins in work first begun in the 1970s. Technologies of Seeing: Photography, Cinematography and Television applies the same model to photographic and cinematographic technologies. The thesis argues that all these media developments can only be understood in a social context; that they are to be understood as examples of what has become known as ‘socially shaped technology’ (or, in terms of the thesis, ‘cultural determinism’). This is contrary to the received dominant view that technology itself is the driver determining social formation – termed the ‘technological determinist’, ‘technicist’ or ‘diffusion theory’ approach. In rejecting technicism, ‘How Does Technological Development And Adoption Occur In The Media? A Cultural Determinist Model’ proposes instead an original, pioneering contribution to a revisionist cultural determinist/SST historiography as well as outlining a model to explicate at a theoretical level how such innovations and adoptions occur.
4

Effect of p300 HAT Activity on Myogenic Differentiation

Hamed, Munerah 23 January 2013 (has links)
Skeletal muscle specification and differentiation programs are regulated by the myogenic regulatory factors which include Myf5, MyoD, myogenin and Mrf4. Upstream of the MRFs, the transcription co-activators and other intracellular and extracellular signals play crucial roles in regulating skeletal myogenesis. Histone acetyltransferase activity of p300 is required for Myf5 and MyoD expression. Furthermore, the MyoD core enhancer region is indispensable for MyoD expression. However, the mechanism by which p300 activates MyoD gene expression is to be determined. The histone acetyltransferase activity of p300 can be inhibited by small molecule inhibitors such as curcumin. Thus, using the inhibitor approach on stem cells is useful to investigate the role of p300 in activating MyoD expression during myogenesis. We here show that curcumin was able to inhibit stem cell determination and differentiation into skeletal myocytes. We also show that p300 is present, and histone acetylation is high at the core enhancer region. Therefore, we provide evidence that p300 is directly involved in MyoD gene expression during skeletal myogenesis.
5

Effect of p300 HAT Activity on Myogenic Differentiation

Hamed, Munerah January 2013 (has links)
Skeletal muscle specification and differentiation programs are regulated by the myogenic regulatory factors which include Myf5, MyoD, myogenin and Mrf4. Upstream of the MRFs, the transcription co-activators and other intracellular and extracellular signals play crucial roles in regulating skeletal myogenesis. Histone acetyltransferase activity of p300 is required for Myf5 and MyoD expression. Furthermore, the MyoD core enhancer region is indispensable for MyoD expression. However, the mechanism by which p300 activates MyoD gene expression is to be determined. The histone acetyltransferase activity of p300 can be inhibited by small molecule inhibitors such as curcumin. Thus, using the inhibitor approach on stem cells is useful to investigate the role of p300 in activating MyoD expression during myogenesis. We here show that curcumin was able to inhibit stem cell determination and differentiation into skeletal myocytes. We also show that p300 is present, and histone acetylation is high at the core enhancer region. Therefore, we provide evidence that p300 is directly involved in MyoD gene expression during skeletal myogenesis.
6

Efeitos de um programa de remediação fonológica em escolares com dislexia do desenvolvimento: monitoramento da evolução terapêutica com o uso do P300 / Effects of a phonological remediation program in schools with developmental dyslexia: therapeutic progress monitoring with use of P300

Ferraz, Érika 27 February 2013 (has links)
Dislexia é um dos distúrbios de aprendizagem, sendo um transtorno específico no aprendizado da leitura. Tem origem constitucional, caracterizado pela dificuldade em decodificar palavras simples, mostrando insuficiência no processo fonológico, não esperada para sua idade cronológica, apesar de instrução convencional, adequada inteligência, oportunidade sociocultural e sem distúrbios cognitivos. O uso de atividades terapêuticas de treino das habilidades fonológicas leva a uma melhora quanto à análise fonológica da linguagem escrita, interferindo diretamente na habilidade de leitura e compreensão. É importante que se busquem meios alternativos para monitorar a evolução terapêutica, principalmente quanto à sua capacidade cognitiva. O objetivo deste estudo foi verificar os efeitos de um programa de remediação fonológica de leitura e escrita em escolares com Dislexia de Desenvolvimento. Foram avaliadas 20 crianças com diagnóstico de dislexia do desenvolvimento, com idade de 8 a 14 anos, sendo o grupo I (GI) composto por 10 escolares submetidos ao programa, e grupo II (GII), composto por 10 escolares não submetidos à remediação. Foram utilizados no processo de avaliação: Prova de Consciência Fonológica; Teste de Nomeação Automática Rápida; Prova de Leitura e Escrita de palavras reais e inventadas; Escrita temática; Prova de Memória de trabalho e teste do Potencial evocado auditivo cognitivo PEAC-P300. Após, foi aplicado o programa de remediação fonológica, de leitura e escrita, realizado em três etapas distintas, com 24 sessões, cumulativas, sendo cada etapa realizada duas vezes por semana, com duração de 30 minutos cada. Na pós-testagem do programa foram reaplicados todos os testes da pré-testagem. Houve diferença estatisticamente significante na pontuação dos testes de consciência fonológica, do acesso ao léxico mental, da memória de trabalho, escrita temática e escrita sob ditado, além da leitura de palavras e pseudopalavras, assim como na latência do componente P3 do PEAC-P300, para o grupo submetido à remediação fonológica, na comparação entre pós e pré testagem, enquanto o GII manteve o mesmo nível de dificuldades. Além disso, encontramos relação entre a alteração de desempenho obtido pelo grupo submetido ao programa entre o teste de consciência fonológica e a latência do componente LN2 do p300. A análise desses resultados revela que houve diferença no desempenho pós-intervenção terapêutica dos participantes do GI nas habilidades, mesmo em curto prazo. O programa de remediação fonológica mostrou-se um método terapêutico de efeitos benéficos e rápidos, proporcionando melhora não apenas quantitativa, mas principalmente qualitativa nos escolares com dislexia do desenvolvimento, quanto ao domínio de habilidades auditivas, fonológicas e de leitura e escrita, favorecida pelo uso do processamento fonológico da informação. Além disso, o PEAC-P300 mostrou-se uma ferramenta útil para o monitoramento da evolução terapêutica, podendo ser utilizado na prática clínica. / Dyslexia is a learning disorder, being a specific disorder in learning of reading. Constitutional origin, characterized by difficulty in decode simple words, showing insufficiency in the phonological process, not expected for his chronological age, despite conventional instruction, adequate intelligence, socio-cultural opportunity, without cognitive disorders. The use of therapeutic activities of training of phonological skills leads to an improvement in phonological analysis with regard to written language, interfering directly in the ability to read and understand. It is important to seek the means to monitor the therapeutic evolution, especially as your cognitive ability. The goal of this study was to verify the performance in evaluation procedures of language in children with developmental dyslexia in pre and post phonological remediation program and reading and writing, prepared from phonological abilities, auditory and visual skills, reading and writing. Were evaluated 20 children diagnosed with developmental dyslexia, aged 8 to 14 years, with the Group I (GI) composed of school 10 submitted to the program, and group II (GII), composed of 10 schools not subject to remediation. Were used in the evaluation process: Phonological Awareness; Rapid Auto-naming test; Proof-reading and writing real words and invented; Thematic writing; Proof of working memory and cognitive auditory evoked potential CAEP-P300. After, was applied the phonological remediation program of reading and writing, in three distinct steps, with 24 sessions, cumulative, with each step performed twice a week, with a duration of 30 minutes each. In the post testing of the program were reapplied all the tests of pre testing.There was a statistically significant difference in score of phonological awareness tests, access to mental lexicon, working memory, thematic writing and written under dictation, and reading words and pseudo-words, as well as the latency of the P3 component of the CAEP-P300, the group submitted to the phonological remediation, in comparison between pre and post testing, while the GII has maintained the same level of difficulty. In addition, we find the relation between the change of performance achieved by the Group submitted to the program between the test of phonological awareness and the LN2 component of P300 latency. The analysis of the results reveals that there was difference in post-intervention performance of participants in the GI in therapy skills, even in the short term. The phonological remediation program proved to be an therapeutic method of beneficial effects and fast, providing improved not only quantitative, but qualitative mainly school development in with dyslexia, as to the field of auditory skills, phonological and reading and writing, favored by use of the phonological processing of information. In addition, the CAEP-P300 proved to be a useful tool for monitoring goal of evolution therapy, and can be used in clinical practice.
7

Efeitos de um programa de remediação fonológica em escolares com dislexia do desenvolvimento: monitoramento da evolução terapêutica com o uso do P300 / Effects of a phonological remediation program in schools with developmental dyslexia: therapeutic progress monitoring with use of P300

Érika Ferraz 27 February 2013 (has links)
Dislexia é um dos distúrbios de aprendizagem, sendo um transtorno específico no aprendizado da leitura. Tem origem constitucional, caracterizado pela dificuldade em decodificar palavras simples, mostrando insuficiência no processo fonológico, não esperada para sua idade cronológica, apesar de instrução convencional, adequada inteligência, oportunidade sociocultural e sem distúrbios cognitivos. O uso de atividades terapêuticas de treino das habilidades fonológicas leva a uma melhora quanto à análise fonológica da linguagem escrita, interferindo diretamente na habilidade de leitura e compreensão. É importante que se busquem meios alternativos para monitorar a evolução terapêutica, principalmente quanto à sua capacidade cognitiva. O objetivo deste estudo foi verificar os efeitos de um programa de remediação fonológica de leitura e escrita em escolares com Dislexia de Desenvolvimento. Foram avaliadas 20 crianças com diagnóstico de dislexia do desenvolvimento, com idade de 8 a 14 anos, sendo o grupo I (GI) composto por 10 escolares submetidos ao programa, e grupo II (GII), composto por 10 escolares não submetidos à remediação. Foram utilizados no processo de avaliação: Prova de Consciência Fonológica; Teste de Nomeação Automática Rápida; Prova de Leitura e Escrita de palavras reais e inventadas; Escrita temática; Prova de Memória de trabalho e teste do Potencial evocado auditivo cognitivo PEAC-P300. Após, foi aplicado o programa de remediação fonológica, de leitura e escrita, realizado em três etapas distintas, com 24 sessões, cumulativas, sendo cada etapa realizada duas vezes por semana, com duração de 30 minutos cada. Na pós-testagem do programa foram reaplicados todos os testes da pré-testagem. Houve diferença estatisticamente significante na pontuação dos testes de consciência fonológica, do acesso ao léxico mental, da memória de trabalho, escrita temática e escrita sob ditado, além da leitura de palavras e pseudopalavras, assim como na latência do componente P3 do PEAC-P300, para o grupo submetido à remediação fonológica, na comparação entre pós e pré testagem, enquanto o GII manteve o mesmo nível de dificuldades. Além disso, encontramos relação entre a alteração de desempenho obtido pelo grupo submetido ao programa entre o teste de consciência fonológica e a latência do componente LN2 do p300. A análise desses resultados revela que houve diferença no desempenho pós-intervenção terapêutica dos participantes do GI nas habilidades, mesmo em curto prazo. O programa de remediação fonológica mostrou-se um método terapêutico de efeitos benéficos e rápidos, proporcionando melhora não apenas quantitativa, mas principalmente qualitativa nos escolares com dislexia do desenvolvimento, quanto ao domínio de habilidades auditivas, fonológicas e de leitura e escrita, favorecida pelo uso do processamento fonológico da informação. Além disso, o PEAC-P300 mostrou-se uma ferramenta útil para o monitoramento da evolução terapêutica, podendo ser utilizado na prática clínica. / Dyslexia is a learning disorder, being a specific disorder in learning of reading. Constitutional origin, characterized by difficulty in decode simple words, showing insufficiency in the phonological process, not expected for his chronological age, despite conventional instruction, adequate intelligence, socio-cultural opportunity, without cognitive disorders. The use of therapeutic activities of training of phonological skills leads to an improvement in phonological analysis with regard to written language, interfering directly in the ability to read and understand. It is important to seek the means to monitor the therapeutic evolution, especially as your cognitive ability. The goal of this study was to verify the performance in evaluation procedures of language in children with developmental dyslexia in pre and post phonological remediation program and reading and writing, prepared from phonological abilities, auditory and visual skills, reading and writing. Were evaluated 20 children diagnosed with developmental dyslexia, aged 8 to 14 years, with the Group I (GI) composed of school 10 submitted to the program, and group II (GII), composed of 10 schools not subject to remediation. Were used in the evaluation process: Phonological Awareness; Rapid Auto-naming test; Proof-reading and writing real words and invented; Thematic writing; Proof of working memory and cognitive auditory evoked potential CAEP-P300. After, was applied the phonological remediation program of reading and writing, in three distinct steps, with 24 sessions, cumulative, with each step performed twice a week, with a duration of 30 minutes each. In the post testing of the program were reapplied all the tests of pre testing.There was a statistically significant difference in score of phonological awareness tests, access to mental lexicon, working memory, thematic writing and written under dictation, and reading words and pseudo-words, as well as the latency of the P3 component of the CAEP-P300, the group submitted to the phonological remediation, in comparison between pre and post testing, while the GII has maintained the same level of difficulty. In addition, we find the relation between the change of performance achieved by the Group submitted to the program between the test of phonological awareness and the LN2 component of P300 latency. The analysis of the results reveals that there was difference in post-intervention performance of participants in the GI in therapy skills, even in the short term. The phonological remediation program proved to be an therapeutic method of beneficial effects and fast, providing improved not only quantitative, but qualitative mainly school development in with dyslexia, as to the field of auditory skills, phonological and reading and writing, favored by use of the phonological processing of information. In addition, the CAEP-P300 proved to be a useful tool for monitoring goal of evolution therapy, and can be used in clinical practice.
8

Characteristics of processing for trait adjectives in depressive persons : an event-related potential study

Shimizu, Hideki, Saito, Hirofumi, Hoshiyama, Minoru 01 1900 (has links)
No description available.
9

An Examination of ERPs produced by Images of Locations and Graspable Objects in an Oddball Task

Gardner, Aaron, Kellicut, Marissa R., Sellers, Eric W., Dr. 05 April 2018 (has links)
Brain-Computer Interface (BCI) technology utilizes EEG to measure the electrical activity at the scalp to be used for operating an external device. Therefore, understanding the cognitive responses that can be measured through the EEG to use BCIs is important. BCI systems, such as the P300 Speller, rely on detecting Event-Related Potentials (ERPs). ERPs are time-locked responses to internal or external events. Previous research has indicated that viewing different categories of stimuli activate specific brain structures and produce stimuli specific ERPs. Since the BCI’s ability to detect differences in ERPs is important for operating the system, we have conducted a traditional oddball study to examine the ERPs elicited by two categories of stimuli – images of locations and images of graspable tools. Functional MRI studies have shown that images of familiar locations produce brain responses in the parahippocampal place area (PPA). The PPA is a region of the ventromedial surface of the temporal lobe that responds more strongly to visual scenes (i.e. images of familiar landscapes) than to other presented visual stimuli and is sometimes better known as a “mapping area” of the brain. Conversely, the premotor cortex is an area of motor cortex that lies within the frontal lobe and is used to produce neural impulses that control the implementation of movement. In this instance, logical movement of tools, such as a hammer, can be used as a stimulus for the activation of the premotor cortex. While research has indicated the activation of these different regions, there has not been any research comparing the ERPs that may be produced by these two categories of stimuli. Therefore, our study uses an oddball task to determine if these two types of stimuli can produce distinct ERPs. We hypothesized that images of tools will produce a distinct ERP response, specifically the P300 response, at frontal electrode locations that will significantly differ from ERP responses produced by images of locations. Furthermore, we hypothesized that images of locations will produce distinct ERPs at parietal locations compared to images of tools. Preliminary data collected from 20 participants has indicated a difference in the P300 response at central electrode locations produced by the two types of stimuli. As we continue with data collection, we anticipate observing differences at the frontal and parietal locations. This would indicate that activating these different structures with distal proximity may provide more robust ERP responses that could be used for future P300 Speller BCI operation.
10

Investigação da estabilidade inter e intra-examinador na identificação do P300 auditivo: análise de erros. / Investigation of inter and intra-examiner stability to P300 auditory identification: analysis of errors.

Junqueira, Cinthia Amorim de Oliveira 09 November 2001 (has links)
O P300 auditivo é um potencial evocado que reflete a atividade neurofisiológica das habilidades cognitivas auditivas de atenção, memória, discriminação e tomada de decisão. A possibilidade de correlacionar aspectos do comportamento auditivo a fenômenos fisiológicos observáveis tem despertado o interesse de profissionais de diversas áreas interessados no estudo das disfunções auditivas. Por ser um procedimento novo, os métodos de análise e interpretação dos resultados ainda não estão padronizados e, portanto, devem ser explorados e discutidos visando maior segurança para aplicação clínica e científica. Este estudo investigou a estabilidade na análise e interpretação do P300 auditivo seguindo um conjunto de regras (critério) pré-determinadas. Para isso, quatro profissionais da área audiológica analisaram, em 2 momentos diferentes, 70 traçados de P300 de crianças e adolescentes saudáveis entre 8 e 18 anos de idade, seguindo as mesmas regras para a identificação das ondas (N1, P2, N2 e P3) e marcação de suas medidas de latência. As medidas de latência da onda P300 foram submetidas a análises qualitativa e quantitativa. A análise qualitativa investigou os tipos de erros cometidos pelo examinador no uso do critério de determinação do P300 (5,9% do total de 560 medidas obtidas). Os erros mais freqüentes no uso do critério foram: não identificar o P300 como a maior onda logo após o complexo N1-P2-N2 e identificar uma “falsa" onda P300. A análise quantitativa investigou a variabilidade da medida da latência do P300 atribuível ao examinador. Os resultados mostraram que não houve diferença significante entre as análises inter e intra-examinador, tendo sido encontradas correlações significantes entre as medidas de latência, indicando boa fidedignidade no teste-reteste e alta concordância entre os examinadores no modo como analisaram os traçados das ondas. O critério usado neste estudo demonstrou ser útil na determinação do P300, podendo ser sugerido com segurança para uso clínico e científico. / The P300 auditory is an evoked potential which reflects the neurophysiological activity of auditory cognitive abilities: attention, memory, discrimination and making decision as well. The possibility of correlation between aspects of auditory behavior and observable physiological phenomena has increased the interest in the study of auditory dysfunctions among professionals of various fields. Due the fact that the P300 is a recent procedure, the methods of its analysis and interpretation have not been standardized yet. Therefore, they must be explored and debated aiming more security for clinical and scientific application. In this study it was investigated the stability in the analysis and interpretation of P300 auditory, according to a pre-determined set of rules. Four audiologists analyzed twice 70 records of P300 of healthy children and adolescents between 8 and 18 years of age, identifying the waves (N1, P2, N2, P3) and their latencies according to the pre-determined set of rule. The P300 latency measurements were submitted to quantitative and qualitative analysis. The qualitative analysis looked into types of errors made by the examiner during the P300 identification (5.9% in a total of 560 measurements). The no-identification of the P300 as the highest wave following the complex N1-P2-N2, likewise the “wrong" identification of P300 wave were the most frequent mistakes. In the quantitative analysis we investigated the variability of the P300 latency measurements attributable to the examiner. The results showed that there were no significant differences between the inter- and intra-examiner analyses. Significant correlations were found between the measurements, showing a good test-retest reliability and high concordance among the examiners in the way they analyzed the wave records. We conclude that the rules used in this study are useful to the identification of the P300 in both clinical and scientific situations.

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