Multisensory contribution in visuospatial orientation: an interaction between neck and trunk proprioception

Abstract

A coherent perception of spatial orientation is key in maintaining postural control. To achieve this the brain must access sensory inputs encoding both the body and the head position and integrate them with incoming visual information. Here we isolated the contribution of proprioception to verticality perception and further investigated whether changing the body position without moving the head can modulate visual dependence—the extent to which an individual relies on visual cues for spatial orientation. Spatial orientation was measured in ten healthy individuals [6 female; 25–47 years (SD 7.8 years)] using a virtual reality based subjective visual vertical (SVV) task. Individuals aligned an arrow to their perceived gravitational vertical, initially against a static black background (10 trials), and then in other conditions with clockwise and counterclockwise background rotations (each 10 trials). In all conditions, subjects were seated first in the upright position, then with trunk tilted 20° to the right, followed by 20° to the left while the head was always aligned vertically. The SVV error was modulated by the trunk position, and it was greater when the trunk was tilted to the left compared to right or upright trunk positions (p < 0.001). Likewise, background rotation had an effect on SVV errors as these were greater with counterclockwise visual rotation compared to static background and clockwise roll motion (p < 0.001). Our results show that the interaction between neck and trunk proprioception can modulate how visual inputs affect spatial orientation.

Visuo-vestibular conflicts within the roll plane modulate multisensory verticality perception

“…Visual cues provide stable references for verticality, for example from buildings and trees, while vestibular signals indicate the location of the head with respect to gravity via the otoliths [12,13]. In addition, proprioceptive and somatosensory signals about the position of the neck and the trunk indicate the position of the longitudinal body axis (i.e., the 'idiotropic vector [14]') and contribute to a prior that the head is usually upright [10,[14][15][16][17][18][19]. Previous studies have demonstrated that tilting either the head or the trunk biases the Subjective Visual Vertical (SVV, [20]).…”