Sleep elicited by olfactory tubercle stimulation and the effect of atropine

The effects of high-frequency olfactory tubercle (TbOf) stimulations were studied on the EEG and behaviour of freely-moving cats. The results were as follows: (1) TbOf stimulation elicited sleep similar in every respect to physiological sleep; (2) statistical evaluation of the results showed that primarily the appearance and maintenance of slow wave sleep was facilitated by the stimulations. Stimulations during paradoxical sleep had no effect, but they did promote the recurrence of slow wave sleep after the paradoxical sleep. The effect of stimulations during wakefulness depended on the on-going activity; (3) TbOf stimulations brought about synchronization, which was characterized by a similar arousal threshold as for physiological sleep; and (4)atropine treatment prevented the behavioural effects and did not influence the EEG effects of the stimulations.