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Master's Dissertation
DOI
10.11606/D.3.2017.tde-12072017-131157
Document
Author
Full name
Diana Constanza Garcia Rincon
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2017
Supervisor
Committee
Baccala, Luíz Antonio (President)
Alfonso, Nestor Felipe Caticha
Sameshima, Koichi
Title in English
Performane of partial directed coherence subject to volume consuction effects.
Keywords in English
EEG
Functional connectivity
Partial directed coherence
Vector autoregressive model
Volume conduction
Abstract in English
The strong relationship between cognitive processing and coherent behaviour and neurocognitive networks justifies the current huge interest in cortical functional connectivity modeling. This has fostered the development of connectivity estimators from the classical bivariate coherence concept to the notion of multivariate partial directed coherence (PDC) which provides information about temporal dependencies exposing cause and effect relationships. This work examines PDC performance for scalp EEG data whose research value has been subject to much debate in the light of the presence of volume conduction (VC) effects that often obscure the actual nature of cortical source dynamics. Through analytical considerations and simulations we show that even though (VC) can hinder accurate connectivity estimation, one can mitigate its effects by a judicious choice of scalp electrode configuration/ground reference. This observation allows settling the connectivity estimation adequacy debate in the presence of PDC.
Title in Portuguese
Desempenho da coerência parcial direcionada sujeita aos efeitos de condução de volume.
Keywords in Portuguese
Eletroencefalografia
Processamento de sinais biomédicos
Processamento digital de sinais
Redes complexas
Abstract in Portuguese
A forte relação que processamento cognitivo e comportamento coerente tem com redes neurocognitivas justifica o enorme interesse atual em modelamento de conectividade cortical. Este fato tem justificado o desenvolvimento de estimadores de conectividade desde a clássica coerência bivariada até a noção multivariada de coerência parcial direcionada (PDC) que exibe informação a cerca de dependências temporais que permitem expor relações de causa e efeito. O presente trabalho examina o desempenho da PDC no contexto de EEG de escalpo cujo valor em pesquisa sob os efeitos de condução de volume (VC) tem sido objeto de uma quantidade substancial de questionamentos na medida em esta obscurece a observação da dinâmica das fontes corticais. Por meio de considerações analíticas e simulações, mostramos que é possível mitigar os erros de estimação devidos à VC através da escolha judiciosa da configuração de eletrodos e da referência de terra. Esta observação permite resolver o conflito acerca da adequabilidade da inferência cortical baseada em EEG de escalpo.
 
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Publishing Date
2017-07-12
 
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