2022
DOI: 10.1016/j.autneu.2022.103021
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Spectral decomposition of cerebrovascular and cardiovascular interactions in patients prone to postural syncope and healthy controls

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Cited by 11 publications
(13 citation statements)
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References 94 publications
(125 reference statements)
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“…𝑝 𝑘=1 [8], being n the time index, k the lag of interactions, p the model order (manually fixed for each subject), 𝑨(𝑘) the 2x2 coefficient matrices defining the time-lagged effects within and between the two processes, and 𝑼 a vector of zero-mean innovation processes with 2x2 covariance matrix 𝜮. The frequency-domain AR representation of the model coefficients leads to obtain the 2x2 transfer matrix as 𝑯(𝑓) = [𝑰 − 𝑨(𝑓)] −1 (being 𝑰 the identity matrix) from which the spectral density matrix of the bivariate process is derived as 𝑺(𝑓) = 𝑯(𝑓)𝚺𝑯 * (𝑓) (* stands for Hermitian transpose).…”
Section: Methodsmentioning
confidence: 99%
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“…𝑝 𝑘=1 [8], being n the time index, k the lag of interactions, p the model order (manually fixed for each subject), 𝑨(𝑘) the 2x2 coefficient matrices defining the time-lagged effects within and between the two processes, and 𝑼 a vector of zero-mean innovation processes with 2x2 covariance matrix 𝜮. The frequency-domain AR representation of the model coefficients leads to obtain the 2x2 transfer matrix as 𝑯(𝑓) = [𝑰 − 𝑨(𝑓)] −1 (being 𝑰 the identity matrix) from which the spectral density matrix of the bivariate process is derived as 𝑺(𝑓) = 𝑯(𝑓)𝚺𝑯 * (𝑓) (* stands for Hermitian transpose).…”
Section: Methodsmentioning
confidence: 99%
“…𝑯). Given (1) and (2), it has been shown [8], [10] that the sum of the two GC terms does not yield the total coupling, so that a spectral measure of the spectral mixing between the two causal directions can be defined as:…”
Section: Methodsmentioning
confidence: 99%
“…It is worth noting that the IC is always zero in the absence of zero-lag effects between the time series, i.e., when the AR model is strictly causal [ 122 ], but this is generally not true in practical analysis, when significant fast effects occur and are no more negligible [ 123 ]. A measure of the so-called “extended GC”, quantifying both time-lagged and instantaneous effects between time series, has also been proposed [ 124 ].…”
Section: Functional Connectivity Estimation Approachesmentioning
confidence: 99%
“…The computation of pairwise GC indexes as a function of frequency is based on: (i) fitting the observed set of time series with a linear parametric model as in ( 2 ); (ii) representing the model coefficients in the Fourier domain; (iii) deriving the frequency-dependent causal relations among signals starting from the definition of DC in ( 9 ). Indeed, it is possible to show that, under the assumption of strict causality, there exists a relationship between the frequency-specific GC and the DC in ( 9 ), the former being defined as the logarithmic counterpart of the latter [ 24 , 122 ]: …”
Section: Functional Connectivity Estimation Approachesmentioning
confidence: 99%
See 1 more Smart Citation