INFLUENCE OF PARADOXICAL SLEEP-DEPRIVATION ON THE INTERMEDIATE STAGE OF SLEEP IN THE RAT

In the rat, paradoxical sleep (PS) is preceded by a short-lasting stag e characterized by high amplitude cortical spindles and low frequency hippocampal theta rhythm. This intermediate stage (IS) is massively ex tended at the expense of PS by barbiturates and benzodiazepines. To fu rther study the relationship between the IS and PS, six rats were PS d eprived for 48 h by sitting on one of three small platforms surrounded by water. A control group of six other rats remained in dry cages wit h shavings. After 24 h PS deprivation the latency of IS occurrence inc reased, was unchanged after 48 h deprivation and decreased during reco very on shavings after 52 h deprivation. The total IS duration, number of episodes and mean duration per episode were unchanged during depri vation but increased during recovery. This recovery was characterized by an increase in the number of PS episodes and the total duration whi le the latency of PS occurrence decreased. The frequency of theta rhyt hm, unchanged for PS, increased for the IS during deprivation and reco very. In conclusion, the IS did not substitute for PS after selective deprivation.