Shared cortical activation dynamics across individuals during virtual navigation
Poster No:
1089
Submission Type:
Abstract Submission
Authors:
Jaeseob Lim1, Sang-Eon Park1, Sang-Hun Lee1, Sang Ah Lee1
Institutions:
1Seoul National University, Seoul, Korea, Republic of
First Author:
Co-Author(s):
Introduction:
During exploration of a new environment, visual information, navigation events, and their importance for spatial memory are unevenly distributed across space and time. Consequently, various brain regions are likely to exhibit dynamic activities corresponding to the different demands of processing and encoding across time. Our study aims to identify the brain regions displaying such dynamic activity through inter-subject correlation analysis of fMRI data and use them to better understand how the human brain processes information as complex events unfold in our day to day experiences.
We hypothesized that to efficiently encode and structure navigational episodes under limited cognitive capacity, the brain heavily allocates resources for visual processing and memory encoding during the occurrence of crucial portions of the episode such as turning or the emergence of a landmark, but not as much at other points in time. If this process fails, and the brain follows a sub-optimal pattern of encoding, it may lead to a decrease in performance, reflected in the memory accuracy of the navigational episode.
We hypothesized that to efficiently encode and structure navigational episodes under limited cognitive capacity, the brain heavily allocates resources for visual processing and memory encoding during the occurrence of crucial portions of the episode such as turning or the emergence of a landmark, but not as much at other points in time. If this process fails, and the brain follows a sub-optimal pattern of encoding, it may lead to a decrease in performance, reflected in the memory accuracy of the navigational episode.
Methods:
44 healthy adults (mean age = 23.2, 25 female) performed a task involving the viewing of first-person navigational episodes through virtual environments and later identifying the correct route or destination on a map. Participants watched 24 different 1-minute episodes in the MRI scanner. Following each movie, participants answered a navigation-related question, choosing a map retracing the correct navigational path or a map marked with the destination location. 33 segmented cortical regions were analyzed using an intersubject correlation (ISC) method, measuring the correlation between one person's activity dynamics and the mean activity dynamics of all other participants.
Results:
With 3 exceptions, all regions exhibited a significant ISC larger than 0 (FDR-adjusted p < 0.05). The occipital regions showed high ISC compared to the other regions. In a subset of the brain regions (occipital regions, parahippocampal gyrus, and precuneus, adjusted p < 0.05), navigation episodes with landmarks showed greater ISC than navigation episodes without landmarks. Notably, these regions did not show a significant increase in average activation during navigation.
ISC in the visual cortex in correct trials exceeded that of incorrect trials (adjusted p < 0.05), while average activation was not related to memory performance. Other brain regions showed no significant differences between correct and incorrect trials.
ISC in the visual cortex in correct trials exceeded that of incorrect trials (adjusted p < 0.05), while average activation was not related to memory performance. Other brain regions showed no significant differences between correct and incorrect trials.
Conclusions:
During navigation, various brain regions displayed shared dynamic processing. Sensory processing regions in the occipital lobe had the highest ISC, while frontal regions associated with higher-level cognitive functions exhibited smaller yet significant ISC.
One factor contributing to ISC was the presence of distinguishable landmarks in the environment. This suggests that events related to landmarks act as temporal anchors, with most individuals similarly encoding them at those moments in the episode.
Memory performance was found to be related to the dynamic activities, rather than the overall activation level, in the visual cortex. Given that the visual cortex reflects visual attention and memory, we suggest that inadequate control of such processes may, in part, explain why some individuals fail to encode the entire navigational event in memory.
These results demonstrate that utilizing ISC as a neural marker of spatiotemporal encoding may provide further insight into the role of various brain regions in the formation of episodic memory, and provide new interpretations which may not be revealed through analyzing average activation level alone.
One factor contributing to ISC was the presence of distinguishable landmarks in the environment. This suggests that events related to landmarks act as temporal anchors, with most individuals similarly encoding them at those moments in the episode.
Memory performance was found to be related to the dynamic activities, rather than the overall activation level, in the visual cortex. Given that the visual cortex reflects visual attention and memory, we suggest that inadequate control of such processes may, in part, explain why some individuals fail to encode the entire navigational event in memory.
These results demonstrate that utilizing ISC as a neural marker of spatiotemporal encoding may provide further insight into the role of various brain regions in the formation of episodic memory, and provide new interpretations which may not be revealed through analyzing average activation level alone.
Learning and Memory:
Long-Term Memory (Episodic and Semantic) 1
Working Memory
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI)
Other Methods 2
Perception, Attention and Motor Behavior:
Attention: Visual
Keywords:
Cognition
Cortex
FUNCTIONAL MRI
Memory
Vision
1|2Indicates the priority used for review
Provide references using author date format
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Sheng, J. (2023). Intersubject similarity in neural representations underlies shared episodic memory content. Proceedings of the National Academy of Sciences, 120(35), e2308951120. https://doi.org/10.1073/pnas.2308951120
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