Mice that are deprived of paradoxical sleep (PS) for 3 days and given electroconvulsive shock (ECS) at one of several intervals after PS deprivation, display a reductio'n in brain-seizure thresholds. Brain-seizure thresholds are invariant in comparable groups of animals that are not deprived of PS. A shortening of the tonic phase of the convulsion is also observed in the PS-deprived animals; these findings suggest that PS-deprived animals receiving compensatory brain stimulation undergo a less severe convulsion. The experimental findings are interpreted to suggest that PS deprivation produces a central-neural change, during which time the brain is much more susceptible to agents that produce amnesia.We have recently produced data showing that electroconvulsive shock (ECS) administered systematically to mice after paradoxical sleep deprivation (PSD), produces memory disruption (retrograde amnesia) by either: (1) interfering with the maintenance of memory (Fishbein, 1971;Fishbein, McGaugh, & Swarz, 1971 and confirmed by Wolfowitz andHoldstock, 1971, in the rat), or by (2) prolonging the fixation phase of the memory-consolidation gradient (Fishbein, 1972). In effect, it appears that PSD prolongs the time that ECS is an effective amnesic agent. Moreover, our findings suggest that the experimental approach of using the synergistic effects of PSD and ECS, rather than PSD alone, is a very fruitful way of uncovering the relationship between PS and memory .Since the underlying biological bases of the synergistic memory-disturbing effects of the PSD + ECS treatment remains unclear, the present experiment was undertaken for the purpose of examining: (1) whether a central-neural change can be detected by the treatment, and (2) the time course of the change, if such a change exists. We imagined that an examination of brain neuroexcitability thresholds might provide at least one measure of the effects that the PSD + ECS treatment has on brain function; the present paper reports on the changes we have observed.
METHOD SubjectsThe subjects are 128 F 2 mice, 60-70 days old, derived from DBA/2J and C57BL/6J strains, obtained from our laboratory's breeding stock.
ApparatusA Lafayette A615B constant-current shocker is used to induce