This study investigates the impact of memory consolidation on the frequency of P-waves during REM sleep in mice, focusing on two distinct types of learning: contextual fear conditioning (CFC) and motor learning via the rotarod test. P-waves, generated by the phasic activation of glutamatergic neurons in the subcoeruleus nucleus (SubC) of the pons, are critical phasic events during REM sleep and are believed to play a role in synchronizing neural activity related to memory processes.

Experiments involved male C57-B6 mice (n=4), each implanted with LFP electrodes in the SubC to record P-waves.

For the CFC task, mice were trained to associate a neutral context with an aversive stimulus, with fear extinction assessed over subsequent days. Results indicated a significant increase in P-wave frequency during the second day of extinction (EXT2) for certain mice, suggesting that P-waves may be involved in the formation of extinction memories, where new non-fearful memories coexist with pre-existing fearful memories.

In the rotarod task, where mice learned to maintain balance on a rotating bar, performance improvements were used as a measure of motor memory consolidation. The analysis revealed that different mice responded variably across experimental days, with no consistent effect of motor memory consolidation on P-wave frequency. This variability suggests that P-waves may play a different role in motor learning compared to contextual learning.

Future research will aim to replicate these findings with larger cohorts to enhance statistical power and explore the effects of optogenetic stimulation or ablation of the SubC on P-wave frequency and memory consolidation. Understanding the role of P-waves in different types of memory consolidation could provide insights into potential therapeutic interventions for memory-related disorders.