Deprivation of P.S. in the pontile animal

Since P.S. is the only form of sleep in pontile animals we turned to a study of the effects of deprivation. Our technique was as follows: at the beginning of each phase of P.S. the fall in nuchal EMG activity, by the intermediary of an Oneirograph, switches on a stimulator which applies electric shocks to the animal's log. The strength of these shocks is regulated to arouse the animal, in which case the reappearance of EMG activity automatically cuts out the stimulation.

Results: Deprivation was maintained for a maximum of 8-9 h. It appeared that when P.S. is suppressed by a shock it tends to recur at ever shorter intervals. At first these intervals are similar to those between periods of P.S. in controls. but after some hours they become so short that 40 60 sec after being wakened by the shock the animal falls into a new phase of P.S. (Fig. 21). Thus the total number of incipient phases of P.S. was as much as 155 in sessions that lasted for 9 h, and P.S. can hardly be suppressed for longer periods than this in view of the very great number of shocks required. When the stimuli were stopped, P.S. returned immediately. Its average duration was then slightly more than that of controls (7 as against 6 min), and its periodicity remained at a higher level for 2-3 h and then returned to normal.

A result such as this exemplifies the necessary nature of P.S. in pontile animals, it suggests an active process situated in the brain stem, the efficacy of which increases as its effect is suppressed.