0076 Memory Consolidation During SWS of Implicit Visuospatial Memory Associated with Odor

Introduction Memory consolidation during sleep is more pronounced during SWS, but this effect depends on the form of learning (implicit or explicit). Also, it is considered that the piriform cortex, the primary olfactory cortex, replay and consolidates the olfactory stimuli perceived before sleep, as well as memories associated with the olfactory stimulus, during SWS. In this study, we investigated the consolidation of implicit visuospatial memory associated with olfactory stimuli during sleep in human subjects. Methods ROCF (Rey-Osterrieth Complex Figure) was used for the visuospatial memory task, and peppermint, liquid paraffin were used as experimental and control stimuli, respectively. Participants performed an implicit learning task in which they copied the ROCF while inhaling the experimental or control odor before nap(No instructions to memorize or test). After the learning, participants completed a baseline test in which they recalled the ROCF without inhaling the odor, and then took a 135-minute nap. After the nap, the ROCF recall test was repeated with inhaling experimental or control odor. Results Data from 28 of the 56 participants for whom SWS appeared were used in the statistical analysis. The analysis revealed that the slow-spindle PSD(Power Spectral Density) during SWS in the prefrontal cortex of the group that inhaled the experimental odor during ROCF learning was lower than that of the group in the control odor inhaled group. The results of linear regression analysis using prefrontal slow-spindle PSD as a moderator showed that when prefrontal slow-spindle PSD was lower than average, the memory performance (hit-rate change of ROCF) of the group that inhaled the experimental odor during ROCF learning was higher than that of the group that inhaled the control odor. This difference disappeared where the slow-spindle PSD exceeded the average. Conclusion Consolidation of odor associated implicit visuospatial memories during SWS was found to be associated with a decrease in prefrontal slow-spindle activity. Prefrontal slow-spindle activity during SWS is associated with the erasure of unstable memories, and olfactory cortex may suppress this activity to make unstable memories into long-lasting memories. Support (if any)