The plethora of everyday active states (waking, sleeping, etc.)
have been reduced to four main states: (1) "open loop"
(2) resting chaos, (3) oscillatory burst, (4) seizure. The states
are listed in order of how much energy is used to sustain that
state, with the "open loop" state using very little and seizure
using the most. The difference in energy usage is most apparent
in the comparison between amplitudes in a
EEG diagram taken for each of the four states.
"open loop" -- deep anesthesia
Characterization: lack of background activity.
When perturbed with electrical stimulus the system quickly returns to rest without osciallation. This seems to indicate that the "open loop" state can be identified with a strong point attractor (very negative Liapunov constant). resting chaos -- waking rest
Characterization: low-amplitude chaotic activity.
When perturbed with electrical stimulus the system falls into exponentially decaying oscillations appearing as a spiral inside the well of its potential (phase) portrait.
Characterization: Extremely high amplitude spike activity.
Under several seconds of intense electrical stimulation an epileptic seizure is released. It is intiated after the failure of excitatory input transmission as shown by the decreasing responses at left to the last 5 pulses of the stimulus train. The seizure spike train then progressively emerges from a relatively quiet post-stimulus state.  The "oscillatory burst" has been saved for last as it embodies the most interesting character -- complexity.
W. J. Freeman
Simulation of Chaotic EEG Patterns witha Dynamic Model of the Olfactory System
Biological Cybernetics. vol.56, pp.139-150, p.146. 1987.