Abstract
(1) Background: Humans use reference frames to elaborate the spatial representations needed for all space-oriented behaviors such as postural control, walking, or grasping. We investigated the neural bases of two egocentric tasks: the extracorporeal subjective straight-ahead task (SSA) and the corporeal subjective longitudinal body plane task (SLB) in healthy participants using functional magnetic resonance imaging (fMRI). This work was an ancillary part of a study involving stroke patients. (2) Methods: Seventeen healthy participants underwent a 3T fMRI examination. During the SSA, participants had to divide the extracorporeal space into two equal parts. During the SLB, they had to divide their body along the midsagittal plane. (3) Results: Both tasks elicited a parieto-occipital network encompassing the superior and inferior parietal lobules and lateral occipital cortex, with a right hemispheric dominance. Additionally, the SLB > SSA contrast revealed activations of the left angular and premotor cortices. These areas, involved in attention and motor imagery suggest a greater complexity of corporeal processes engaging body representation. (4) Conclusions: This was the first fMRI study to explore the SLB-related activity and its complementarity with the SSA. Our results pave the way for the exploration of spatial cognitive impairment in patients.
Highlights
IntroductionMultiple sources of afferent information (from vestibular, visual, and proprioceptive receptors) and efferent information (from motor effectors) are needed to elaborate internal spatial representations of the body in space [1,2]
Multiple sources of afferent information and efferent information are needed to elaborate internal spatial representations of the body in space [1,2]
Using functional magnetic resonance imaging (fMRI), the present study investigated the neural bases of processes elicited by two different egocentric tasks in healthy participants: subjective straight-ahead task (SSA) and subjective longitudinal body plane task (SLB)
Summary
Multiple sources of afferent information (from vestibular, visual, and proprioceptive receptors) and efferent information (from motor effectors) are needed to elaborate internal spatial representations of the body in space [1,2]. These inputs can be integrated into different and changing systems of coordinates, depending on the person’s position in space and the nature of the task. The egocentric reference frame encodes spatial information centered on body coordinates [3,4,5,6,7,8] This frame involves two spatial components, depending on the intended action: extracorporeal and corporeal [9]. It is essential to improve knowledge in this field, as gaining a better understanding of the mechanisms involved in elaborating the egocentric reference frame would inform rehabilitation strategies for patients with spatial cognition disorders following stroke
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