Non-linear analysis of emotion EEG: Calculation of Kolmogorov entropy and the principal Lyapunov exponent

For 76 healthy subjects, two non-linear measures, capturing the dynamical properties of the system orbiting within the attractor (i.e. Kolmogorov entropy, K2 and principal Lyapunov exponent, L1), were calculated from EEG segments, corresponding to different states of brain activity, induced by emotionally valenced (i.e. neutral, affective positive and negative) video stimuli. Significantly elevated values of EEG K2 and L1 in response to both positive and negative film categories as compared to neutral one were evidenced. Relying on the obtained findings, it is suggested that increased cortical dynamics, up to a certain level, are probably necessary for emotion functioning. (C) 1997 Elsevier Science Ireland Ltd.