Scene construction ability in post-traumatic stress disorder across adolescence and adulthood

This dissertation found that PTSD can impair the ability to imagine detailed, coherent scenes, and that lateral eye movements alter gaze patterns and reduce imagery vividness, offering insight into how eye movements may support memory processing in EMDR therapy.

Article Abstract

“Memory disturbances and associated hippocampal dysfunction are a primary feature of post-traumatic stress disorder (PTSD). A hallmark symptom is experiencing intrusive traumatic memories that are vivid and experienced in-the-moment, yet fragmented; however, individuals also experience other memory problems, including impaired mental simulation of past and future events. In this dissertation, I report three studies that examine scene construction ability—a form of mental simulation that involves imagining multimodal and spatially coherent scene imagery—in individuals with PTSD recruited through the clinic (Chapter 3) or community (Chapter 4 and 5). Chapter 3 found robust PTSD-related impairments in terms of reduced detail generation, greater fragmentation, and reduced subjective quality (i.e., presence and salience). By using an additional spatial navigation task and structural and diffusion-tensor MRI, spatial processing deficits in both tasks were found to be associated with reduced integrity to long-range white matter tracts implicated in multisensory integration, whereas detail generation deficits were associated with smaller hippocampal volumes. Chapter 4 examined if these behavioural deficits can be seen in adolescence, given that PTSD-related hippocampal differences may not yet be apparent. No overall deficits were noted, however adolescents with PTSD reported fewer sensory details but with greater presence. This suggests a reduced sense of embodiment even within their imagination, which may be a target for intervention. Given the critical role of eye movements in memory processing, Chapter 5 examined gaze differences during scene construction as well as the effect of making lateral saccades on scene imagery. Although no overall scene construction deficits were noted, those with PTSD displayed a lower fixation rate which lateral eye movements equalized, while also reducing the scenes subjective quality. Given eye movements are an integral component of a popular treatment for PTSD (eye-movement desensitization and reprocessing therapy, EMDR), these findings shed light on a potential mechanism of this therapy. Together, these studies indicate neural, gaze, and psychopathological factors (e.g., disorder onset, if treatment- seeking) associated with PTSD-related deficits in scene construction ability, which can inform the development and mechanistic understanding of different therapeutic treatments. These results are also compatible with relational processing accounts of mental simulation and contribute to the broader literature on hippocampal function.”

Article Access

Open Access

Marlatte, H. G. (2025). Scene construction ability in post-traumatic stress disorder across adolescence and adulthood. [Doctoral Thesis, University of Toronto]. https://hdl.handle.net/1807/150143(opens in new tab)