Postural changes during eye-head movements

Area of Science:

• Biomechanics
• Neuroscience
• Human Movement Science

Background:

• Postural control is crucial for stability.
• The interplay between visual, vestibular, and somatosensory systems influences posture.
• Eye-head coordination plays a significant role in maintaining balance.

Purpose of the Study:

• To investigate the impact of combined eye and head movements on postural sway.
• To determine the temporal relationship between eye-head movements and changes in center of pressure (COP).
• To explore the anticipatory nature of postural adjustments during visual-motor tasks.

Main Methods:

• Young subjects stood on a force plate while wearing a helmet with a laser.
• Visual targets were presented at various angular displacements.
• Subjects were instructed to align a laser spot with targets using eye-head movements.
• Center of pressure (COP) and electromyography (EMG) were recorded.

Main Results:

• Anterior-posterior COP changes were most pronounced during downward movements, with short latencies.
• COP adjustments frequently preceded the onset of downward head movements.
• EMG activity in biceps femoris and gastrocnemius correlated with these anticipatory COP changes.
• Eye-only movements did not consistently alter ground reaction forces.

Conclusions:

• Eye-head movements significantly influence postural sway.
• Anticipatory postural adjustments, indicated by COP changes, precede head movements during visual-motor tasks.
• These findings highlight the predictive role of the sensorimotor system in maintaining balance during dynamic visual-motor tasks.