Caffeine attenuates paradoxical sleep deprivation induced- memory impairment during paradoxical sleep windows in rats

There is considerable evidence to support the hypothesis of relationship between paradoxical sleep (PS) and learning–memory processing. It has been suggested that PS is important in memory retention at the specific time course called PS windows (PSW). The time of PSWs occurrence and duration of these PSWs following the training sessions and, the neurochemical nature of PSWs has not been well known. In this research the duration of PSWs and the effect of caffeine on memory retention in these periods has been investigated. For this purpose, male NMRI rats were trained in a two–way shuttle avoidance task (100 trials in one session) and their memory retention was tested one week after learning. In experiment 1, the baseline EEG and EMG activity 1-4 hr after training was recorded. In those animals that reached to 70% learning criteria (learner group), the total duration of PS increased significantly (P