Awareness of voluntary action, rather than body ownership, improves motor control

Kazumichi Matsumiya

doi:10.1038/s41598-020-79910-x

Kazumichi Matsumiya

Open Access

https://doi.org/10.1038/s41598-020-79910-x

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Abstract

Awareness of the body is essential for accurate motor control. However, how this awareness influences motor control is poorly understood. The awareness of the body includes awareness of visible body parts as one’s own (sense of body ownership) and awareness of voluntary actions over that visible body part (sense of agency). Here, I show that sense of agency over a visible hand improves the initiation of movement, regardless of sense of body ownership. The present study combined the moving rubber hand illusion, which allows experimental manipulation of agency and body ownership, and the finger-tracking paradigm, which allows behavioral quantification of motor control by the ability to coordinate eye with hand movements. This eye–hand coordination requires awareness of the hand to track the hand with the eye. I found that eye–hand coordination is improved when participants experience a sense of agency over a tracked artificial hand, regardless of their sense of body ownership. This improvement was selective for the initiation, but not maintenance, of eye–hand coordination. These results reveal that the prospective experience of explicit sense of agency improves motor control, suggesting that artificial manipulation of prospective agency may be beneficial to rehabilitation and sports training techniques.

Highlights

Awareness of the body is essential for accurate motor control
To estimate the body’s state for motor control, the brain must distinguish between signals generated as a consequence of voluntary body part movement and signals arising from events in the external world
There was no significant interaction between action and timing conditions (t19 = 1.39, P = 0.17 n.s.). These results indicate that (i) sense of body ownership over the computer graphics (CG) hand is sensitive to timing but not action, and (ii) sense of agency over the CG hand is sensitive to action but not timing, suggesting that the moving rubber hand illusion36 (RHI) technique used in the present study can manipulate senses of body ownership and agency independently

Summary

Introduction

Awareness of the body is essential for accurate motor control. how this awareness influences motor control is poorly understood. To estimate the body’s state for motor control, the brain must distinguish between signals generated as a consequence of voluntary body part movement and signals arising from events in the external world. A more recent fMRI and rTMS study addressed this issue with implicit sense of a gency[13], no study investigates the relationship with explicit sense of agency It remains unclear whether sense of body ownership affects motor control. Estimation of the body’s state for motor control does not seem to require the visual component of body ownership There is another clinical evidence for the behavioral dissociation between somatoparaphrenia (disturbed sense of body ownership) and anosognosia for hemiplegia (disturbed sense of agency)[31]. This makes it difficult to ascertain whether body ownership truly affects the motor system

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