Investigating the Neural Bases of Egocentric Spatial Reference Frame After Right‐Hemisphere Stroke: Brain Lesions and Disconnectome Analyses of Subjective Straight Ahead and Longitudinal Body Axis Misperception

ABSTRACT Spatial cognition impairments have been shown to reduce autonomy, partly due to alterations in the egocentric spatial reference frame. However, little is known about the neural substrates underlying these impairments, particularly in terms of structural connectivity. We aimed to investigate the neural bases of two complementary components of the egocentric spatial reference frame by analysing both lesion locations and probabilities of white matter disconnection. Fifty‐seven individuals with right‐hemispheric strokes were included. Egocentric spatial representation was assessed using the subjective straight ahead (SSA) and the longitudinal body axis (LBA). Voxel‐based lesion‐symptom mapping and disconnectome analyses using BCBtoolkit were performed to study the relationship between SSA and LBA misperceptions, lesion location, and probabilities of white matter disconnection. SSA and LBA misperceptions were associated with partially dissociable neural patterns. SSA misperception was mainly associated with right parieto‐frontal lesions and with an exploratory association involving the posterior corpus callosum. In contrast, LBA misperception was associated with right temporo‐occipital lesions and disconnections involving the right inferior longitudinal fasciculus, right cingulum fasciculus, posterior corpus callosum, and right inferior fronto‐occipital fasciculus. These exploratory findings suggest that SSA and LBA misperceptions, although assessed in the same egocentric reference system, rely on distinct neural substrates. SSA may place greater demands on action‐oriented spatial processing in extracorporeal space, whereas LBA may rely more strongly on cross‐modal integration between an internal body‐centred representation of the longitudinal body axis and a visual cue. Assessing both tasks may help improve the characterisation and rehabilitation of spatial cognition impairments after right‐hemisphere stroke. Trial Registration Number and Date of Registration: The original study was approved by the Institutional Review Board of Poitiers‐France III West No. 051216. The trial was registered before first inclusion (NCT01677091)