Using High-Density EEG to Identify Sleep-Dependent Cortical Replay of Laboratory Analog Trauma and Effects on Distressing Dreams and Intrusive Memories
Abstract
The proposed research project addresses the Peer Reviewed Medical Research Program Portfolio Neuroscience, the Topic Areas Sleep Disorders and Restriction and Trauma, and the Strategic Goal Foundational Studies. Posttraumatic stress disorder (PTSD) occurs in 8% to 10% of civilians, and 20% to 30% of combat Veterans. Core features of PTSD are distressing memories of traumatic experiences during wake, and trauma-related nightmares at night. Nightmares occur in the majority of individuals with PTSD and are associated with severe subjective distress and numerous negative outcomes, including suicide. Similar to distressing memories during wake, nightmares are considered an intrusive, re-experiencing symptom of the disorder because they manifest as vivid memories of lived trauma experiences, ranging from brief fragments to extensive, complex distressing replays of traumatic memories. There is now strong evidence that wake distressing memories impact sleep symptoms, and vice versa, indicating a vicious cycle through which unwanted daytime and nighttime trauma symptoms reinforce each other and perpetuate PTSD. Despite the distress and negative outcomes associated with nightmares, and their bidirectional relationship with classic wake intrusive memories in PTSD, extremely little is understood about their neurobiology. However, a growing scientific understanding of learning and memory indicates that sleep plays a fundamental role in off-line memory consolidation through networks of neurons (brain cells) that fire during sleep in patterns that replay the neuronal firing patterns of wake experiences. This sleep replay results in consolidation of the neuronal traces of daytime experiences into memories. Innovative science also demonstrates that electroencephalography (EEG), a non-invasive strategy for measuring brain activity, can provide information about this process. For example, EEG collected during wake learning and subsequent sleep can capture brain activity patterns that are repeated across wake and sleep states and can predict how well information is learned and/or recalled. Similar methods have shown that patterns of EEG activity during sleep can also be used to predict content of dreams that is described when subjects are awakened from sleep. Research has also shown that dreaming about something learned before sleep can enhance memory for that information. This fascinating research indicates that sleep, dreams, and memory are intricately linked. This is of critical relevance to PTSD, since PTSD revolves around the memory of a traumatic event, and recurrent trauma dreams and wake trauma memories are a core feature of the disorder. Cracking the code that creates and reinforces trauma memories during both sleep and wake would result in a major breakthrough in the science and would provide critical information relevant to PTSD prevention and treatment. Our Discovery Award proposal comprises an initial step in cracking the code, using EEG in a laboratory experiment involving medically healthy male and female Veterans along with sophisticated EEG data analysis strategies. The main part of the study involves one laboratory visit with EEG data collection during wake tasks followed by an early afternoon nap. During the visit, participants will initially view a series of brief trauma movie clips (established by Veterans to be highly distressing in a preparatory phase of our project), along with control (non-trauma) clips. Trauma clips will serve as laboratory analogs of true trauma experiences, enabling us to study how distressing experiences are registered and imprinted in the brain. After viewing, participants will also go through a series of trials during which they will briefly imagine the most distressing scenes from the trauma clips. They will subsequently have a 2-hour nap opportunity. EEG measurement will take place continuously throughout the wake and sleep procedures. After the laboratory visit, participants will
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2024
- Source ID
- HT94252310024
Entities
People
- Anne Richards
Organizations
- San Francisco VA Medical Center
- United States Army