Understanding the Roles of Phasic and Tonic REM Sleep in Memory Consolidation

Poster Session E - Monday, April 15, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Ashwin Harimohan¹ (aharimoh@uwo.ca), Laura Batterink¹; ¹Western University

During sleep, newly formed memories are strengthened and integrated with existing memories. According to several leading proposals, this consolidation process occurs sequentially. First, repeated re-activation of newly encoded memories occurs during non-rapid-eye movement (NREM) sleep. Next, these memories are integrated into established memory networks during REM sleep. The heterogeneity of non-REM periods of sleep is well-characterized and considered in physiological analyses, whereas REM sleep is most often treated as one homogenous single state. However, previous studies have shown that REM sleep consists of two microstates, the phasic and tonic microstates. The phasic microstate resembles a stable sleep period associated with the restorative functions of sleep, while the tonic microstate consists of quiescent segments associated with environmental awareness. Despite these distinctions, there has been limited research analyzing the specific REM microstates in relation to sleep-dependent memory consolidation. We aim to bridge this gap in knowledge by examining the differential contributions of phasic and tonic REM activity in memory consolidation during sleep. Using previously collected datasets, we will analyze the microarchitecture of REM sleep and measure the relationship between phasic and tonic REM activity and behavioural indices of memory changes from the pre-sleep to post-sleep period. We hypothesize that phasic activity will positively correlate with increased post-nap memory performance, along with other physiological sleep indicators of memory consolidation, specifically spindle power during slow-wave sleep. These findings will provide further insight into the role of REM sleep and the sequential interactions between NREM and REM sleep in memory consolidation.

Topic Area: LONG-TERM MEMORY: Other