Measures of Entropy and Complexity in altered states of consciousness
arXiv Preprint Archive January 9, 2017 D. M. Mateos, R. Guevara Erra, R. Wennberg et al.
Wakefulness is characterized by greater complexity of brain signals compared to sleep or epileptic seizures. Scalp and intracerebral EEG and MEG recordings were analyzed using Permutation Entropy and Permutation Lempel Ziv Complexity. A complexity vs entropy graph showed that entropy and complexity values are highest during fully alert states and fall during states with loss of awareness or consciousness. These results were robust across all three recording types. The authors suggest that investigating cognition through complexity frameworks may reveal mechanistic aspects of brain dynamics in altered states of consciousness as well as normal and pathological conditions.