Seeing your foot move changes muscle proprioceptive feedback

Abstract

Multisensory effects are found when the input from single senses combines and this has been well-researched in the brain. Presently, we examined in humans the potential impact of visuo-proprioceptive interactions at the peripheral level, using microneurography, and compared it with a similar behavioral task. We used a paradigm where participants had either proprioceptive information only (no vision) or combined visual and proprioceptive signals (vision). We moved the foot to measure changes in the sensitivity of single muscle afferents, which can be altered by the descending fusimotor drive. Visual information interacted with proprioceptive information, where we found that for the same passive movement, the response of muscle afferents increased when the proprioceptive channel was the only source of information, as compared with when visual cues were added, regardless of the attentional level. Behaviorally, when participants looked at their foot moving, they more accurately judged differences between movement amplitudes, than in the absence of visual cues. These results impact our understanding of multisensory interactions throughout the nervous system, where the information from different senses can modify the sensitivity of peripheral receptors. This has clinical implications, where future strategies may modulate such visual signals during sensorimotor rehabilitation.

Significance Statement It is well known that multisensory processes occur in the brain, yet we know little about the consequences of multisensory interactions at the spinal level. We recorded from single muscle afferents, while participants either saw or did not see their foot moving. We show that adding visual information reduces muscle afferent firing, probably via descending commands by fusimotor efference. These results impact sensorimotor rehabilitation, where clinical strategies using exercises without visual feedback may promote proprioceptive training.