Ws. Pritchard et al., APPLICATION OF DIMENSION ESTIMATION AND SURROGATE DATA TO THE TIME EVOLUTION OF EEG TOPOGRAPHIC VARIABLES, International journal of psychophysiology, 24(3), 1996, pp. 189-195
Dimensional complexity (estimated correlation dimension) was measured
for two topographic EEG time series: (a) the time evolution of global
field power (GFP) and (b) the time evolution of sequential dissimilari
ty (SQD) for resting, eyes-closed and eyes-open data. Eyes-closed GFP
and eyes-closed/open SQD all had an element of nonlinearity in their d
ynamics as evidenced by increased dimensional complexity associated wi
th the phase-angle randomization, Gaussian surrogate-data procedure. H
owever, none of the three gave any evidence of being deterministic cha
otic processes. Eyes-open GFP dimensional complexity could not be dist
inguished from a linear-stochastic process.