Measuring spectrally-resolved information transfer
Fig 4
Spectrally resolved transfer entropy for the null-case (example 1).
(A) Top, a ‘source’ S0 and a ‘target’ T1 of an uncoupled system. Bottom, power spectra of S0 and T1. (B) Spectrally resolved Transfer Entropy. Each panel, except those at the bottom, shows the mTE′ distribution obtained from the surrogate datasets with shuffled coefficients at the scale indicated to the left, or, equivalently, the frequency band indicated at the top of each panel. White bars represent histograms of surrogate data, i.e. relative frequencies in (a.u.), the red dashed line is the median of the surrogate mTE′ distribution, the black dashed line is the original mTE value. The horizontal black line indicates the distance δTE between the original mTE and the median of the surrogate distribution (**, p < 0.005; *, p < 0.05). These display conventions will be kept for figures displaying spectrally resolved TE analyses. The temporal surrogate analysis using surrogates constructed by permuting blocks of samples in the time-domain is shown in the bottom row. No significant drop of the shuffled wavelet coefficients could be found, since no information transfer occurred between a putative source and the target site. (Note that the choice of source or target here is arbitrary since no coupling was simulated).