[Increase of paradoxical sleep, induced by injection of ibotenic acid in the ventrolateral posterior hypothalamus in the cat].

The intratissular injection of ibotenic acid into the ventrolateral part of the posterior hypothalamus induced a dramatic biphasic and transient hypersomnia immediately after disappearance of the anaesthesia (14 to 24 hrs. after injection). The duration of hypersomnia was related to the dose of neurotoxin injected. Its first period was characterized by an increase in paradoxical sleep (PS) (300%). Then, during the second phase, PS disappeared and there was a subsequent increase of slow wave sleep (SWS) (60%). Finally, on the third day, all cats recovered control level of PS and SWS.