0086 Beyond the DRM Paradigm: Sleep Facilitates False Memories of Composite Words

Abstract Introduction Considerable evidence supports the beneficial effects of sleep on memory and learning, including the consolidation and reorganization of memories and the extraction of regularities from encoded experiences. In addition, some studies suggest that sleep may also increase false memories, potentially as a byproduct of regularity extraction. Time-compressed memory replay in the hippocampus during non-rapid-eye-movement (NREM) sleep is thought to support consolidation, yet the functional role of this temporal compression remains unclear. We recently proposed that compressed replay may enable the association of events that occurred at disparate times, thus supporting the extraction of temporal regularities. Consequently, the model predicts that sleep might also facilitate a specific new form of false memory, in which two separate events that occur consecutively are later encoded as a single composite event. The current work investigates this prediction. Methods Male and female adults were presented with a series of word pairs (e.g., car, pet) that could form a new composite word when combined (e.g., carpet). Following a retention interval that contained either sleep or wake, they then underwent a surprise memory test for these composite words. EEG was recorded during sleep to examine the contribution of NREM sleep, focusing on slow-wave and spindle-related parameters. Results As predicted, participants who slept showed higher rates of false memories for composite words than those who remained awake, indicating that sleep actively facilitated the formation of composite false memories. EEG analyses showed that some slow-wave and spindle-related measures predicted increased false composite memories, whereas other NREM parameters were associated with fewer false memories. The associations with physiological measures were specific for a forward presentation of the words during the initial exposure (car, pet) and were not evident when word components were presented in the backward direction (pet, car). Conclusion Our findings support the idea that sleep, and specifically NREM sleep, can promote a distinct class of false memories in which temporally adjacent events are compressed into a single composite representation. The pattern of EEG–behavior relationships partly resembles prior work on non-composite false memories, suggesting a possible competitive interaction between semantic and episodic consolidation processes during sleep. Support (if any) NSF/EFRI 2317706 partly supported this work.