[Waking mechanisms: multiple networks in the mesencephalic reticular formation].

The hypothesis of a unique waking system located in the mesencephalic reticular formation is no longer tenable. Cortical and behavioral waking depends upon a complicated network of different systems which interact with each other with different neurotransmitters. The hierarchy of the internal structure of this network is not yet known. However, the inhibition of some strategic crossroads in this network is sufficient to suppress wake and induce sleep.