Telencephalic and rhombencephalic sleep in the cat
Jouvet M.
The Nature of Sleep Ciba Foundation Symposium Churchill (1961)
TABLE OF CONTENTS

Introduction

Materials and methods

Results

Topography of the systems responsible for the two stages of sleep

Mechanisms of the rhombencephalic phase of sleep

Conclusions

Discussion
Figures

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Conclusions

These results enable us to dissociate the two phases of sleep which are relatively independent of one another. The EEG tracing of decorticate or mesencephalic cats shows no slow phase whereas periods of "rhombencephalic sleep" persist. In the cats with a pontile R.F. lesion, on the other hand, only the phase of "slow sleep" appears, without any p.p. These facts lead us to accept the intervention of two different systems during physiological sleep in the cat.

(1) The first system appears to intervene during " spindles and slow waves" sleep in the intact animal. It requires the presence of the neocortex which is responsible for the slow activity. This corticifugal slow activity expresses an inhibition phenomenon since the arousal threshold produced by direct stimulation of the reticular formation rises during this stage. This phase may there fore be described as telencephalic sleep. It is possible that this telencephalic stage may represent a stage which is acquired during telencephalization and that it could be described as "neosleep".

(2) The phase of "rapid" sleep- (paradoxical phase) which we propose to call the "rhombencephalic phase" is dependent upon a totally different system, situated at the level of the pontile reticular formation. It controls, through the inhibitory R.F., the somato-vegetative phenomena (disappearance of all muscular tonic activity even in the cases of decerebration or decerebellation hypertony, variation in respiratory and cardiac rhythms). The rapid cortical activity which accompanies this phase is not suppressed by the interruption of the activating reticular system. This phase of sleep which only exists in mesencephalic or pontile cats could be likened to an "archisleep". This phase is more profound than the first one as the threshold of awakening is increased in comparison with that of the slow wave phase of sleep. Finally, it can be triggered off in animals by stimulating the lower part of the brain stem, and it is suggested that this phase depends upon a neurohumoral mechanism.

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