Own-Body Perception in the Encoding and Retrieval of Memories for Naturalistic Events

1068 

Abstract Submission 

Heather Iriye¹, H. Henrik Ehrsson²

¹Karolinska Institutet, Solna, Select a State, ²Karolinska Institutet, Stockholm, Select a State

Heather Iriye  
Karolinska Institutet
Solna, Select a State

H. Henrik Ehrsson, Professor  
Karolinska Institutet
Stockholm, Select a State

The vivid, coherent perception of one's own body (i.e., body ownership) during memory encoding facilitates retrieval (Bergouignan, Nyberg, & Ehrsson, 2014; Iriye, Chancel & Ehrsson, In Press; Iriye & Ehrsson, 2022). Yet, the underlying mechanism explaining how perception of our bodies contributes to memory is unclear. Body ownership may act as a contextual memory cue since it is typically a constant feature of both encoding and retrieval. Alternatively, body ownership may be a privileged type of information that supports memory beyond contextual memory effects, given its high self-relevance.

Here we measured patterns of activity in core brain areas involved in contextual memory (i.e., the angular gyrus, parahippocampus, hippocampus, and medial prefrontal cortex; Preston & Eichenbaum, 2013) as we manipulated body ownership during the encoding and retrieval of immersive videos (Figure 1). We predicted that consistent strong body ownership between encoding and retrieval would impact the strength of a memory trace in the medial prefrontal cortex, as this region uses contextual information to bias the selection of memory details during retrieval5. We immersed healthy participants (N = 25) within videos seen through virtual reality glasses, which depicted lifelike events that included a first-person view of a mannequin's reclining body aligned with participants' real bodies during fMRI scanning. Participants saw an object touch the mannequin and synchronously felt touches on the corresponding location of their real body, which created an illusory sense of ownership over the mannequin. As a control condition, we disrupted the illusion by delivering seen and felt touches asynchronously in half of the videos. 1 week later, participants were re-immersed within videos depicting the mannequin receiving dynamic visuotactile stimulation overlaid on still-frames of the previously seen videos during fMRI scanning. We again manipulated feelings of ownership over the mannequin, which was either congruent or incongruent with how a video was encoded, while participants retrieved memories for the videos. Participants completed ratings of emotional intensity, vividness, reliving and belief in memory accuracy to assess subjective remembering.

Peak skin conductance response magnitudes to bodily threats directed towards the mannequin were greater in the synchronous versus asynchronous condition (p = .006), demonstrating greater ownership over the mannequin's body. Using a multivariate classifier and region-of-interest approach, we found that patterns of activity during memory retrieval in the angular gyrus, parahippocampal cortex, hippocampus, and medial prefrontal cortex predicted current body ownership perception in the context of body ownership perception during encoding (p's < .003). Next, we used encoding-retrieval pattern similarity to test whether patterns of activity during encoding were reinstated more at retrieval for memories formed and recalled with strong body ownership perception, considering subjective remembering measures of emotional intensity, vividness, reliving, and belief in memory accuracy. We compared patterns of neural activity in the medial prefrontal cortex to a target dissimilarity matrix weighted for congruent strong body ownership perception at encoding and retrieval and increasing levels of subjective remembering measures (Figure 2A). Consistent strong body ownership perception at encoding and retrieval combined with increasing levels of emotional intensity led to stronger memory reinstatement (i.e., higher encoding-retrieval pattern similarity) in the medial prefrontal cortex (p = .008).

Together, our results suggest that the influence of own-body perception on our ability to remember past events cannot be solely attributed to contextual memory effects. Rather, strong consistent body ownership perception during encoding and retrieval may calibrate patterns of activity in medial prefrontal regions to support remembering.

Long-Term Memory (Episodic and Semantic) ¹

Multivariate Approaches

Perception: Multisensory and Crossmodal ²

Perception: Tactile/Somatosensory

FUNCTIONAL MRI

Memory

Multivariate

Perception