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Effects of neck muscle proprioceptive activation on the dynamics of monocularly driven horizontal vergence movements
1Department of Ophthalmology, Karolinska Institute, Huddinge University Hospital, Stockholm, Sweden.
Purpose:
The dynamics of accommodative vergence responses were studied to accommodative stimuli combined with the activation of neck muscle proprioception.
Methods:
Accommodative stimulation was done with a LED bar. The stimuli were presented monocularly in a stepwise and a sinusoidal mode to either the dominant or the non-dominant eye with the other eye covered. The neck proprioceptors were activated by vibration on the neck muscles which turn the head horizontally. Eye movements were recorded with an infra-red reflection system in both eyes.
Results:
Vibration of the neck muscles shortened the time constant of the accommodative vergence movement in the covered eye to square wave stimulation when the non-dominant eye was fixating the targets. The gain factor to sine wave stimulation was higher when the non-dominant eye was fixating.
Conclusion:
Extraretinal signals from neck proprioception influenced not only the static eye position, but also the dynamics of monocularly driven accommodative vergence movements, when the non-dominant eye was the viewing eye.
Insights
Neck proprioception influences eye movements. Neck muscle vibration altered accommodative vergence dynamics, particularly when the non-dominant eye was viewing, affecting both response speed and gain.
Area of Science:
- Neuroscience
- Ophthalmology
- Vision Science
Background:
- Understanding the interplay between neck proprioception and visual-motor control is crucial for explaining complex human movements.
- Previous research has focused on static eye position, but the dynamic effects of neck proprioception on vergence are less understood.
Purpose of the Study:
- To investigate how activating neck muscle proprioception affects the dynamics of accommodative vergence responses.
- To determine if these effects differ based on which eye (dominant or non-dominant) is stimulated.
Main Methods:
- Monocular accommodative stimulation (LED bar) was applied in stepwise and sinusoidal modes to either the dominant or non-dominant eye.
- Neck proprioceptors were activated using vibration on horizontal neck muscles.
- Bilateral eye movements were recorded using an infrared reflection system.
Main Results:
- Neck muscle vibration shortened the time constant of accommodative vergence in the covered eye during square-wave stimulation when the non-dominant eye fixated.
- The gain factor of accommodative vergence was higher for sine-wave stimulation when the non-dominant eye was fixating.
Conclusions:
- Extraretinal signals from neck proprioception dynamically influence monocularly driven accommodative vergence.
- These proprioceptive signals impact both the speed and gain of vergence responses, especially when the non-dominant eye is the primary viewing eye.