Functional neuro-anatomy of egocentric versus allocentric space representation

Are All Spatial Reference Frames Egocentric? Reinterpreting Evidence for Allocentric, Object-Centered, or World-Centered Reference Frames

“…Despite the wide variety of tasks (and definitions) employed to probe allocentric spatial cognition, most studies fall into three broad categories: (1) spatial judgment tasks, e.g., tasks requiring subjects to report left/right locations relative to egocentric or object-centered coordinates (e.g., Galati et al, 2000 ; Neggers et al, 2006 , similar to Figure 4B ); or requiring spatial proximity or alignment judgments between two objects or objects and the ego (e.g., Saj et al, 2014 ); (2) spatial navigation tasks (virtual, imagined, or remembered; e.g., Committeri et al, 2004 ; Zhang and Ekstrom, 2013 ); and (3) allocentrically-guided movements, e.g., pointing or reaching to spatial targets relative to another object vs. relative to the ego (e.g., Thaler and Goodale, 2011 ; Chen et al, 2014 ).…”

“…In general, both egocentric and allocentric tasks have been reported to activate overlapping parieto-frontal networks, with generally greater egocentric than allocentric activations in superior parietal and superior frontal cortex, especially in the right hemisphere (Galati et al, 2000 , 2010 ; Committeri et al, 2004 ; Neggers et al, 2006 ; Zhang and Ekstrom, 2013 ; Chen et al, 2014 ; Saj et al, 2014 ). Additional foci of greater egocentric than allocentric activation have been reported in superior or middle temporal gyrus (Neggers et al, 2006 ).…”

Where is the ‘subjective straight ahead’ in Williams syndrome?

“…As mentioned in the introduction, the important distortion of the body's internal representation on the SSA and difficulties in using the egocentric frame of reference have been reported in literature in stroke patients (for a review see Rousseaux et al ). Neuroimaging studies suggest that this egocentric reference is coded in a network that includes the parietal cortex in stroke patients (Rousseaux et al ) and healthy control subject (Lester & Dassonville ; Saj et al ). Nevertheless, Atkinson et al () used the orientation‐coding task and found that WS participants were able to match orientation similarly to TD controls but experienced difficulties when additional motor action was required.…”

“…Studies of patients with parietal lesions using the SSA task showed a distortion of the body's sagittal plane representation and a deficit in the egocentric frame of reference (Ferber & Karnath ; Rousseaux et al ). Neuroimaging studies suggested that this egocentric reference is coded in a network that includes the parietal cortex in stroke patients (Rousseaux et al ) as well as in healthy control subjects (Saj et al ). In individuals with WS, structural and functional magnetic resonance imaging studies have reported dysfunction and grey matter abnormalities in parietal areas that could be responsible for their visuo‐spatial deficit (Hocking et al ; Koran et al .…”

Leftward Deviation and Asymmetric Speed of Egocentric Judgment between Left and Right Visual Fields

“…The egocentric representation of space is elaborated by the integration of visual, auditory, proprioceptive and vestibular information relative to the eye, head, and torso position of the observer (Andersen et al, 1997). Recent functional magnetic resonance imaging studies have found that the right hemisphere has more activity than the left hemisphere when healthy right-handed subjects perform egocentric discrimination tasks (Galati et al, 2000, 2001; Neggers et al, 2006; Chen et al, 2012; Saj et al, 2014). The egocentric judgment is frequently tested by measuring the location of subjective straight ahead (SSA), which subjectively separates the egocentric space into left and right halves.…”