Attention to the body depends on eye-in-orbit position

Abstract

Attentional selectivity in touch is modulated by the position of the body in external space. For instance, during endogenous attention tasks in which tactile stimuli are presented to the hands, the effect of attention is reduced when the hands are placed far apart than when they are close together and when the hands are crossed as compared to when they are placed in their anatomical position. This suggests that both somatotopic and external spatial reference frames coding the hands’ locations contribute to the spatial selection of the relevant hand. Here we investigate whether tactile selection of hands is also modulated by the position of other body parts, not directly involved in tactile perception, such as eye-in-orbit (gaze direction). We asked participants to perform the same sustained tactile attention task while gazing laterally toward an eccentric fixation point (Eccentric gaze) or toward a central fixation point (Central gaze). Event-related potentials recorded in response to tactile non-target stimuli presented to the attended or unattended hand were compared as a function of gaze direction (Eccentric vs. Central conditions). Results revealed that attentional modulations were reduced in the Eccentric gaze condition as compared to the Central gaze condition in the time range of the Nd component (200–260 ms post-stimulus), demonstrating for the first time that the attentional selection of one of the hands is affected by the position of the eye in the orbit. Directing the eyes toward an eccentric position might be sufficient to create a misalignment between external and somatotopic frames of references reducing tactile attention. This suggests that the eye-in-orbit position contributes to the spatial selection of the task relevant body part.

Finger posture modulates structural body representations

“…Participants were instructed to keep their gaze directed towards a black sticker on the wall in front of them aligned with their body midline to keep head 40 and gaze position 41 42 constant. At the beginning of each trial a pair of tactile stimuli were presented simultaneously after a variable interval, ranging from 0 to 1000 ms. By stimulating different pairs of fingers, we created situations in which there were zero (i.e., thumb-index, index-middle, middle-ring, ring-little), one (i.e., thumb-middle, index-ring, ring-little), or two (i.e., thumb-ring, index-little) fingers in-between the stimulated fingers.…”

Neurophysiological and neurocognitive mechanisms underlying the effects of yoga-based practices: towards a comprehensive theoretical framework

“…fMRI data indicate that inhibiting saccades and redirecting gaze toward a target engages a frontal oculomotor network including the medial frontal cortex, frontal and supplementary eye fields, and the striatum, known to be involved in action inhibition and performance monitoring (Thakkar et al, 2014 ). Furthermore, evidence from ERP studies suggests that gazing at a body part enhances tactile acuity (Forster and Eimer, 2005 ), spatial attention, (Gherri and Forster, 2014 ), and more generally activation of fronto-parietal networks representing peripersonal space (Gillmeister and Forster, 2010 ).…”

How our body influences our perception of the world

“…Of course the direction of gaze is usually also the point to which attention is directed and attention is known to affect some aspects of tactile perception (Michie et al, 1987) in a way that depends on eye position (Gherri and Forster, 2014). However, Harrar and Harris (2009) found, by overtly orienting attention away from eye position, that attention could account for only about 17% of the effect.…”

“…The orientation of the eyes and head are also involved in determining the perceived location of a touch such that the perceived location of a touch is shifted depending on gaze position ( Harrar and Harris, 2009 ; Pritchett and Harris, 2011 ). Of course the direction of gaze is usually also the point to which attention is directed and attention is known to affect some aspects of tactile perception ( Michie et al, 1987 ) in a way that depends on eye position ( Gherri and Forster, 2014 ). However, Harrar and Harris (2009) found, by overtly orienting attention away from eye position, that attention could account for only about 17% of the effect.…”