Distinct Neural Dynamics of Spatial Transformations: Egocentric Perspective-Taking and Allocentric Rotation.

Background/

Objectives

Egocentric and allocentric spatial transformations are central to spatial cognition, yet it is unknown whether they rely on the same neural mechanisms. The goal of this study was to examine whether egocentric transformations engage the neural processes associated with mental rotation in visual-spatial working memory.

Methods

High-density EEG was recorded while participants performed two matched pointing-direction tasks, in which they indicated the direction toward a target location, while instructed to use either allocentric array rotation or egocentric perspective-taking. Response times and accuracy were recorded, and event-related potential (ERP) responses were analyzed as a function of rotation angle (100° vs. 160°) and differences between front and back pointing directions.

Results

Response times increased with rotation angle in both tasks, whereas a front-back asymmetry in accuracy was observed only in perspective-taking. Both tasks showed rotation-related ERP modulation, but the timing and spatial distribution of these effects differed across tasks. In the array-rotation task, rotation-related ERP effects were observed over right-parieto-occipital regions at 460-510 ms. In the perspective-taking task, the ERP effects were observed over left-central regions at 400-470 ms and 520-610 ms. ERP differences between front and back directions were robust and widespread in the egocentric condition but limited in the allocentric condition.

Conclusions

Perspective-taking does not show the posterior rotation-related ERP effect associated with mental rotation of object representations in visual-spatial working memory. Instead, it appears to reflect updating of the observer-centered reference frame, consistent with simulated self-motion processes involving vestibular and proprioceptive signals.