0063 Sleep Deprivation Impairs Short-term Object Recall on a Serial Novel Object Recognition Task in Rats

Abstract Introduction Novel Object Recognition (NOR) is a rodent behavioral task used to test recall based on the time taken to explore a novel versus familiar object. Sleep deprivation (SD) compromises object discrimination, but time of day and interphase interval (IPI) are important to performance. While the effects of SD on NOR have been investigated with a single object recall opportunity, SD preceding short-term recall combined with serial trials has not been reported. Serial paradigms are important for establishing baseline performance and predicting future performance altered by practice effect and habituation. Here we present a unique serial NOR paradigm that assesses baseline performance, SD, and IPI effects. Methods Male Sprague Dawley rats (N=20) were housed on a ZT0-ZT12 light cycle with baseline NOR testing at ZT12. Ten rats were randomly assigned to SD during the light cycle and the remaining controls slept undisturbed. Treatment testing also occurred at ZT12, after which SD rats were allowed to sleep, and recovery testing followed at ZT14 or ZT16. Each testing session included three phases: acclimation (no objects), familiarization (identical objects), and recognition (novel/identical objects) with < 4 minutes between phases. The recognition phase object discrimination ratio (DR) was analyzed using a mixed-effects ANOVA, with fixed effects of testing (baseline, treatment, recovery), group (control, SD), and their interaction. Secondary analyses assessed the effect of recovery-delay timing (ZT14, ZT16). Results There was a significant main effect of group (F[1,18]=7.64,p=0.013) and group by test interaction (F[2,36]=6.52,p=0.004). There were no differences between groups at baseline or recovery and no differences in recovery-delay. During the treatment test, SD rats were unable to recognize the novel object compared to controls (p< 0.001), spending more time with the familiar object (p< 0.001). Control rat performance worsened at recovery compared to treatment (p=0.033). Conclusion The serial NOR established baseline performance, which was associated with behavioral changes over time. SD significantly inhibited short-term recall, while controls presented stable performance from baseline to treatment testing, with significant performance deficits from treatment to recovery. This decrement may stem from habituation due to a short IPI and/or a time-of-day effect. Support (if any) WSU College of Medicine Department of Translational Medicine and Physiology