Motion perception of head or trunk modulates cervico-ocular reflex (COR)

Area of Science:

• Neuroscience
• Vestibular System
• Oculomotor Control

Background:

• The vestibulo-ocular reflex (VOR) stabilizes gaze during head movements.
• The cervico-ocular reflex (COR) contributes to gaze stabilization using neck proprioception.
• Understanding the interplay between VOR and COR is crucial for deciphering sensorimotor control during motion.

Purpose of the Study:

• To investigate the influence of movement frequency on perceived motion during combined trunk and head movements.
• To examine how attentional focus on head versus trunk motion affects oculomotor responses.
• To differentiate the contributions of vestibular and cervical afferents to gaze stabilization.

Main Methods:

• 15 healthy volunteers participated in the study with eyes covered.
• Sinusoidal body movements around the vertical axis were performed at 0.05, 0.1, and 0.2 Hz with 40 degrees amplitude.
• Subjects were instructed to focus on either imagined head motion or perceived trunk motion.

Main Results:

• At low frequencies (0.05 s-1), subjects primarily perceived illusory head movement when the trunk moved against a fixed head.
• At higher frequencies (0.2 s-1), subjects accurately perceived trunk movement, with diminished illusory head motion.
• Imagining head motion during COR increased eye shifts and saccadic amplitudes, while focusing on trunk motion decreased these parameters.

Conclusions:

• Movement perception is frequency-dependent, transitioning from illusory head motion to accurate trunk motion perception.
• Attentional focus significantly modulates oculomotor responses related to the cervico-ocular reflex.
• These findings highlight the dynamic interaction between vestibular and cervical inputs in sensorimotor control.