“…A number of other non-linear statistics have been used to investigate changes in the EEG: correlation density (LEANER, 1996;MARTINERIE et al, 1998), cross-correlation integral (LE VAN QUYEN et al, 1999;2000;2001), Lyapunov exponents IASEMIDIS et al, 1999;SACKELLARES et al, 2000), similarity measures (HIVELY, 1999) and non-linear predictability (BLINOWSKA and MALINOWSKI, 1991;HERN~NDEZ et al, 1995;CASDAGLI et aL, 1996;CASDAGLI, 1997). The fundamental link between all these non-linear statistics is that they are defined with respect to a particular state space, if the distribution of points in this state space varies, then these statistics are likely to change.…”