Impact of Somatosensory Input Deficiency on Subjective Visual Vertical Perception in Children With Reading Disorders

Abstract

Purpose: Preliminary evidence indicated that children with a reading disorder (RD) may have deviance in their ability to perform high demanding cognitive tasks, such as reading, depending on somatosensory inputs. Until now, only anecdotical reports suggested that improving somatosensory inputs may influence their ability to maintain a stable perception of the visual world despite continuous movements of our eyes, head, and body. Here, we investigated whether changes in upright perception, the subjective visual vertical (SVV), were modulated by somatosensory inputs in a group of children with RD. Method: The SVV task was used under two distinct conditions, i.e., with or without somatosensory inputs from the foot. We enrolled a group of 20 children with reading disorders and 20 sex-, age-, IQ- matched children with neurotypical development. Results: Responses to the SVV task were found to be significantly less accurate in children with RD than in children with neurotypical development (p < 0.001). In the latter, SVV response did not depend on somatosensory inputs from the foot. In contrast, in children with RD somatosensory inputs, either improved or worsen their SVV depending on the tilt direction (p < 0.01). Conclusion: Our results suggested that SVV responses in children with RD could be related to an immaturity for heteromodal sensory integration, including somatosensory inputs.

Keywords: brain; children; cognitive rehabilitation; dyslexia; multisensory integration.

Figure 1

Experimental set up used. The child is standing on with the feet on foam (Orthomic®), and the laser strip is projected on the wall in front of him/her. The laser strip can be tilted at 15° in clockwise (CW) and in counterclockwise (CCW) directions, and the child has to inform the experimenter when he/she perceived the laser strip vertical. The remote to the orientation of the laser strip is quiet and can be used step by step or in continuous movement.

Figure 2

Mean subjective visual vertical and standard error measures (in degree) in children with reading disorder and children with neurotypical development, under two distinct somatosensory conditions (without and with foam under the feet) performed in each tilt direction [clockwise (CW) or counterclockwise (CCW)].