I had to look this up to. Here is an interesting chunk:
EEG researchers are noticing extremely high brainwave frequencies above Gamma, at up to 100 Hz. Totally opposite speed brainwave frequencies - some at 100 Hz and others at less than 0.5 Hz - have exactly the same states of consciousness associated with them. These high-range brain frequency states are named HyperGamma. Later information showed new evidence of frequencies even higher than this, at almost 200 Hz.named: Lambda brainwave frequencies and states of consciousness.
EEG researchers are noticing extremely high brainwave frequencies above Gamma, at up to 100 Hz. Totally opposite speed brainwave frequencies - some at 100 Hz and others at less than 0.5 Hz - have exactly the same states of consciousness associated with them. These high-range brain frequency states are named HyperGamma. Later information showed new evidence of frequencies even higher than this, at almost 200 Hz.named: Lambda brainwave frequencies and states of consciousness.
http://www.bethcoleman.net/gamma.html