Neurological and behavioral features of locomotor imagery in the blind

Kaoru Amemiya,Satoshi Hirose,Tsuyoshi Ikegami,Tomoyo Morita,Eiichi Naito,Masaya Hirashima

doi:10.1007/s11682-020-00275-w

Abstract

In people with normal sight, mental simulation (motor imagery) of an experienced action involves a multisensory (especially kinesthetic and visual) emulation process associated with the action. Here, we examined how long-term blindness influences sensory experience during motor imagery and its neuronal correlates by comparing data obtained from blind and sighted people. We scanned brain activity with functional magnetic resonance imaging (fMRI) while 16 sighted and 14 blind male volunteers imagined either walking or jogging around a circle of 2 m radius. In the training before fMRI, they performed these actions with their eyes closed. During scanning, we explicitly instructed the blindfolded participants to generate kinesthetic motor imagery. After the experimental run, they rated the degree to which their motor imagery became kinesthetic or spatio-visual. The imagery of blind people was more kinesthetic as per instructions, while that of the sighted group became more spatio-visual. The imagery of both groups commonly activated bilateral frontoparietal cortices including supplementary motor areas (SMA). Despite the lack of group differences in degree of brain activation, we observed stronger functional connectivity between the SMA and cerebellum in the blind group compared to that in the sighted group. To conclude, long-term blindness likely changes sensory emulation during motor imagery to a more kinesthetic mode, which may be associated with stronger functional coupling in kinesthetic brain networks compared with that in sighted people. This study adds valuable knowledge on motor cognition and mental imagery processes in the blind.

Highlights

Motor imagery is a multisensory emulation process associated with an action, especially when people imagine a previouslyKaoru Amemiya, Tomoyo Morita and Satoshi Hirose contributed to this work.Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Among these possible sensory modalities, kinesthesia and vision have been considered as important sensory components in motor imagery (Imbiriba et al 2006; Munzert et al 2009)
Imagery time was similar to actual time in the sighted group regardless of condition, whereas imagery time became shorter in the blind group in both conditions
We found novel evidence that imagery time becomes shorter in blind participants during training. functional magnetic resonance imaging (fMRI) results indicated that spatio-visual components more intruded into imagery in the sighted group, while blind participants were capable of having relatively pure kinesthetic motor imagery as per Clusters x y z

Summary

Introduction

Among these possible sensory modalities, kinesthesia and vision have been considered as important sensory components in motor imagery (Imbiriba et al 2006; Munzert et al 2009). Owing to the multisensory nature of motor imagery, even when participants are instructed to generate kinesthetic motor imagery (imagining their own actions as if they move their body parts and feel sensations of movement from the first-person perspective; Jackson et al 2006), visual components often infiltrate motor imagery (Hétu et al 2013; Munzert et al 2009) This holds true only for participants with normal sight whose sensory information processing largely relies on vision in daily life.

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Results

Conclusion