mechanisms of vivid memory

Another line of work currently underway examines how neural and oculomotor systems contribute towards vivid remembering, a cardinal feature of intrusive memories. Vivid recollection is theorized to be supported by the visual and oculomotor systems, since these systems help instantiate perceptual or scene-based details, upon which feelings of vividness or reliving rely. Past studies have independently found relationships between vivid memory and visual brain regions (e.g., occipital cortex, precuneus), and between vivid memory and eye movements (e.g., more fixations). In my current work, I aim to examine relationships between all three: vivid memory, brain activity, and oculomotor activity.

In one such study, I reanalyzed data from an fMRI study (Palombo, 2013), in which 44 participants silently retrieved autobiographical memories in the scanner and provided ratings of subjective reexperiencing. As an important innovation, I used AI/deep learning (DeepMReye) to decode gaze position during the AM task from BOLD in eye voxels; in other words, producing eye-tracking data without an eye-tracker. Preliminary analyses of these AI-predicted eye movement data have indicated significant relationships with memory vividness, whereby recent memories evoked higher fixation rates and greater gaze dispersion than remote memories. Further analyses are underway to test our prediction that the benefit of more fixations during AM retrieval will be recapitulated in brain activity related to vision and imagery, such as hippocampal-occipital functional connectivity. Importantly, we are also currently extending this work to trauma-exposed individuals (e.g., paramedics) with and without PTSD diagnoses. By identifying key brain networks and eye movement patterns involved in vivid recollection, we will be able to examine how these basic mechanisms may change with trauma exposure and PTSD.