“…Subsequent improvements included detection of the state of the patient (sleep versus awake) and elimination of artifacts associated with that state Wang, 1991, 1992). Other algorithms have been employed using such techniques as neural networks (Gabor et al, 1996;Gabor, 1998;James et al, 1999;Ko and Chung, 2000), independent component analysis (Kobayashi et al, 1999(Kobayashi et al, , 2001(Kobayashi et al, , 2002, and wavelet analysis (Khan and Gotman, 2003). Most recently, non-linear techniques (Jing and Takigawa, 2000;Lehnertz, 1999;Li et al, 2003;Litt and Echauz, 2002;Navarro et al, 2002) have been employed using such quantities as the correlation dimension, Lyapunov exponent, Kolmogrov entropy, marginal predictability and similarity index.…”