MICHFL jOUVET 479 



best index, just as iii man, w ould be the muscle tone. In cats, the best place to record 

 it, is the nucchal muscles. We never use the EEG alone to decide if the animal is 

 sleeping, but we correlate the EEG and these indexes. That is the advantage of the 

 polygraphic recording. 



Grastyan. Fast activity, during sleep was first described by Kleitman and 

 Dement who found it to be characteristic ot dreaming. Dement has also found it in 

 cats. It was surprising to find at the same time that a continuous slow activity in the 

 hippocampus existed, in this stage of the sleep. We have never seen so continuous 

 and marked slow waves in an aroused animal. We have tried to influence and 

 artificially elicit this activity and found that in deep sleep, stimulation of the 

 reticular formation by a mild electrical stimulus has provoked this dream-like 

 activity, without any sign of a behavioural arousal. We observed as you did, that 

 the cat loses his tone, but I cannot agree with you that this stage represents a 

 deeper stage of sleep than that oi' the slow activity. The first evidence is that 

 stimulation of the reticular formation could induce this activity. If we stimulated 

 with strong stimuli we got a full arousal. I think that the fast activity observed on 

 the neocortex sleep is a partially aroused state of the nervous system, a stage between 

 the deepest sleep and full arousal. 



JouvET. As far as I know, it was first reported in 1955 by Rimbaud, Passouant 

 and Cadilhac that it is possible to record fast activity during behavioural sleep in 

 cats. The problem of the level of sleep is ditiicult. If we use, as a measure of this 

 level, the threshold of behavioural arousal by stimulation of the reticular forma- 

 tion, we found a higher threshold during the paradoxal stage than during the first 

 stage oi sleep. We don't know what is the behavioural interpretation of this 

 paradoxal stage. We are faced with a very peculiar pattern of nervous activity. 

 There is some evidence which permits us to think that this activity represents 

 dreams. But dreams are perhaps a routine activity of the brain during sleep, the 

 function of which is unknown 



REFERENCE 



Apelbauin, J., Silva. E. E. and Frick, O. : Frequency discrimination and "armisar reaction. 

 18. XXI International Congress of Physiolot^ical Sciences. Buenos Aires, August y-15, 

 I'jyj. Abstracts of Communications. 



