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Timing of Allocentric and Egocentric Spatial Processing in Human Intracranial EEG
Sofiia Moraresku1,2, Jiri Hammer3, Radek Janca4
1Laboratory of Neurophysiology of Memory, Institute of Physiology, Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czechia. sofiia.moraresku@fgu.cas.cz.
Brain Topography
|July 20, 2023
Summary
Egocentric (self-centered) spatial processing appears to be a primary cognitive function, with object-centered (allocentric) representations potentially derived from it. This intracranial EEG study reveals distinct timing and brain areas for each reference frame.
Area of Science:
- Cognitive Neuroscience
- Neurophysiology
- Spatial Cognition
Background:
- Spatial reference frames (RFs), egocentric (self-centered) and allocentric (object-centered), are crucial for spatial cognition, perception, memory, and navigation.
- Previous fMRI studies identified neural correlates but lacked the temporal resolution to clarify the interaction and timing between egocentric and allocentric RFs.
Purpose of the Study:
- To determine the precise timing of egocentric and allocentric information processing using intracranial EEG (iEEG).
- To identify the specific brain areas involved in processing egocentric and allocentric spatial reference frames.
Main Methods:
- Intracranial EEG (iEEG) was recorded from 37 epilepsy patients performing a spatial judgment task in a virtual arena.
- Broad gamma activity (50-150 Hz) was analyzed to investigate the temporal dynamics of spatial reference frame processing.
- Analysis focused on identifying overlapping and selective brain regions for egocentric and allocentric RFs.
Main Results:
- Overlapping activation for both egocentric and allocentric RFs was observed in numerous brain regions, alongside several selective areas.
- Allocentric responses showed later peak activity compared to egocentric responses in frontal regions.
- Egocentric selectivity emerged earlier than allocentric selectivity in several selective brain areas, with maximal egocentric channels in the medial occipito-temporal region and allocentric channels near the intraparietal sulcus.
Conclusions:
- Findings support the hypothesis that egocentric spatial coding is a more primary process, with allocentric representations potentially being derived from egocentric ones.
- The study suggests a broader understanding of the dorsal and ventral streams' roles in processing egocentric and allocentric spatial information, respectively.
