A carregar...
Publicação
Rhythmic evoked electrodermal responses (REER) - um novo método de estudo do sistema nervoso simpático
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 8.31 MB | Adobe PDF |
Autores
Orientador(es)
Resumo(s)
O Sistema Nervoso Autónomo (SNA) é responsável pela regulação automática de diversas
funções vitais à vida. Os métodos que permitem avaliar o SNA muitas vezes não permitem distinguir
entre os seus subsistemas, sendo que aqueles que avaliam apenas o Sistema Simpático são dispendiosos,
invasivos, desconfortáveis ou demorados na sua realização.
Esta dissertação procura verificar a possibilidade da utilização de sinais de atividade
eletrodérmica (EDA) como um método não invasivo, eficiente e acessível para avaliar o funcionamento
do SNA, através da validação de um fenómeno registado num estudo anterior, onde se sugeriu a
existência de uma relação direta entre estímulos visuais e o respetivo sinal eletrodérmico (Atividade
Eletrodérmica Evocada, ou REER).
Neste estudo, participaram 34 indivíduos adultos e sem patologia associada. O sinal de EDA foi
recolhido durante a apresentação de um estímulo visual de xadrez, com três taxas de inversão a
frequências de 0.5, 1.5 e 2 Hz.
Realizou-se o processamento e caracterização dos dados de forma a estudar a possível relação
consistente entre o sinal de EDA e os estímulos apresentados.
Inicialmente, fez-se uma comparação dos parâmetros extraídos através do processamento entre
os vários grupos. O tempo de latência mostrou ser um parâmetro com alterações coerentes para as três
frequências, sendo também o que melhor permitiu distinguir os grupos de dados relativamente a cada
uma das frequências. Verificou-se uma diminuição da latência para as frequências mais elevadas, o que
deverá estar associado a um menor tempo para o SNA processar o estímulo e elaborar uma resposta.
Finalmente, fez-se o estudo da relação do sinal com o estímulo, tendo-se observado que todas as
frequências produzem resultados muito similares.
As evidências encontradas são indicativas de que o que assumiu ser atividade eletrodérmica
evocada anteriormente poderá ser ruído proveniente de fenómenos fisiológicos como a frequência
cardíaca.
O trabalho de investigação descrito nesta dissertação foi realizado de acordo com as normas
estabelecidas no código de ética da Universidade Nova de Lisboa. O trabalho descrito e o material
apresentado nesta dissertação, com as exceções claramente indicadas, constituem trabalho original
realizado pela autora.
The Autonomic Nervous System (ANS) is responsible for the automatic regulation of various vital life functions. Methods that allow the assessment of the ANS often do not distinguish between its subsystems, and those that assess only the Sympathetic Nervous System can be expensive, invasive, uncomfortable, or time-consuming to perform. This dissertation aims to investigate the possibility of using electrodermal activity (EDA) signals as a non-invasive, efficient, and accessible method to evaluate the functioning of the ANS. This is achieved through the validation of a phenomenon recorded in a previous study, where a direct relation- ship between visual stimuli and the corresponding electrodermal signal (Rhythmic Evoked Electroder- mal Responses or REER) was suggested. In this study, 34 adult individuals without associated pathologies participated. EDA signals were collected during the presentation of a chessboard visual stimulus with three reversal rates at frequencies of 0.5, 1.5, and 2 Hz. Data processing and characterization were carried out to explore the potential consistent relation- ship between the EDA signal and the presented stimuli. Initially, a comparison of the parameters ex- tracted through processing was conducted among the various groups. Latency time was found to be a parameter with consistent changes for all three frequencies and was also the parameter that best distin- guished the data groups for each frequency. A decrease in latency was observed for higher frequencies, which is likely associated with a shorter time for the ANS to process the stimulus and formulate a re- sponse. Finally, a study of the relationship between the signal and the stimulus was conducted, and it was observed that all frequencies produced very similar results. The evidence found suggests that what was previously assumed to be evoked electrodermal ac- tivity is likely noise originating from physiological phenomena such as heart rate. The research work described in this dissertation was carried out in accordance with the norms established in the ethics code of Universidade Nova de Lisboa. The work described and the material presented in this dissertation, with the exceptions clearly indicated, constitute original work carried out by the author.
The Autonomic Nervous System (ANS) is responsible for the automatic regulation of various vital life functions. Methods that allow the assessment of the ANS often do not distinguish between its subsystems, and those that assess only the Sympathetic Nervous System can be expensive, invasive, uncomfortable, or time-consuming to perform. This dissertation aims to investigate the possibility of using electrodermal activity (EDA) signals as a non-invasive, efficient, and accessible method to evaluate the functioning of the ANS. This is achieved through the validation of a phenomenon recorded in a previous study, where a direct relation- ship between visual stimuli and the corresponding electrodermal signal (Rhythmic Evoked Electroder- mal Responses or REER) was suggested. In this study, 34 adult individuals without associated pathologies participated. EDA signals were collected during the presentation of a chessboard visual stimulus with three reversal rates at frequencies of 0.5, 1.5, and 2 Hz. Data processing and characterization were carried out to explore the potential consistent relation- ship between the EDA signal and the presented stimuli. Initially, a comparison of the parameters ex- tracted through processing was conducted among the various groups. Latency time was found to be a parameter with consistent changes for all three frequencies and was also the parameter that best distin- guished the data groups for each frequency. A decrease in latency was observed for higher frequencies, which is likely associated with a shorter time for the ANS to process the stimulus and formulate a re- sponse. Finally, a study of the relationship between the signal and the stimulus was conducted, and it was observed that all frequencies produced very similar results. The evidence found suggests that what was previously assumed to be evoked electrodermal ac- tivity is likely noise originating from physiological phenomena such as heart rate. The research work described in this dissertation was carried out in accordance with the norms established in the ethics code of Universidade Nova de Lisboa. The work described and the material presented in this dissertation, with the exceptions clearly indicated, constitute original work carried out by the author.
Descrição
Palavras-chave
Atividade Eletrodérmica (EDA) Estímulo visual Sistema Nervoso Autónomo Sistema Nervoso Simpático Atividade Eletrodérmica Evocada Processamento de Sinal