Abstracts

Rationale:
Déjà vu is the phenomenon of experiencing a new situation with an overwhelming sense of familiarity. It is an experience that has been recorded across the general population with a modified form prominent in patients with temporal lobe epilepsy (TLE). Although the experience of déjà vu has been correlated with alterations in electrical activity within the medial temporal lobe, the ability to study the neural correlates of déjà vu has been limited due to the rarity of spontaneous déjà vu and the difficulty of replicating the distinct experience of novelty and familiarity in a laboratory setting. The Gestalt familiarity hypothesis suggests that this experience can be elicited when the configuration of elements within an environment maps onto a spatial configuration previously seen. This has been validated with 2D representations of spatial similar scenes, and using an early forerunner of virtual reality, but we sought to develop a modern immersive version of this task for use in patients during intracranial monitoring to better understand the neural correlates of this phenomenon.
Method:
We developed an immersive virtual reality (VR) experience following the Gestalt familiarity hypothesis for eliciting déjà vu in patients with TLE. We designed a series of 64 pairs of configurationally mapped VR scenes utilizing the frameworks available within the Unity Game Engine. The scenes were designed to be presented on the HTC Vive Pro head-mounted display to fully immerse participants while also recording eye-tracking data. The task was designed to elicit dèjà vu by guiding participants through a series of 16 scenes during an encoding phase which would be followed by a recall phase. During the recall phase, participants would view a series of 32 spatially mapped and unmapped scenes while being promoted to indicate their experience of familiarity and novelty.
Results:
We have succeeded in developing parallel immersive experiences with identical spatial mapping and categorically dissimilar objects. We are able to obtain continuous eye tracking data at high temporal resolution during the presentation to understand how scene scanning relates to experiences of familiarity. We can obtain pushbutton input from the subject when a sense of familiarity/déjà vu occurs and rate experiences with questions following each presentation. Presently, there is complete control of movement of the subject through virtual space and scenes can be exported to other platforms. The acquisition of patient and subject data has been delayed by COVID-19.
Conclusion:
While similar methods for eliciting déjà vu using the Gestalt familiarity hypothesis have been tested in the past, this task combines modern advancements in VR and eye-tracking technology to develop a more robust and ecologically valid framework for studying  déjà vu. We will be able to evaluate this approach to eliciting déjà vu by examining activity in the perirhinal area and hippocampus, comparing this to experiences elicited by stimulation of the perirhinal area and superior temporal gyrus as has been previously described. Due to the task’s multi-platform versatility, it will likely be very useful in understanding the experience of dèjà vu in both clinical and non-clinical populations.
Funding:
:Research reported in this publication was supported by the National Institute Of Neurological Disorders And Stroke of the National Institutes of Health under Award Number K08NS105929. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.