Effect of aging on the human initial interaural linear vestibulo-ocular reflex

Area of Science:

• Neuroscience
• Ophthalmology
• Gerontology

Background:

• The linear vestibulo-ocular reflex (LVOR) stabilizes gaze during head translation.
• Understanding age-related changes in the LVOR is crucial for assessing balance and visual stability in older adults.

Purpose of the Study:

• To investigate age-related alterations in the human linear vestibulo-ocular reflex (LVOR).
• To compare the LVOR response to unpredictable head translation between young and older adult groups.

Main Methods:

• Eight older (65±7 years) and nine younger (24±5 years) subjects underwent whole-body heave translation (0.5 g).
• Binocular eye rotations were measured using magnetic search coils.
• Head position and acceleration were recorded with a potentiometer and accelerometer.
• Visual targets at 200 cm, 50 cm, and 15 cm were used in light and darkness.

Main Results:

• Older subjects exhibited significantly prolonged LVOR latency (62±3 ms) compared to younger subjects (42±3 ms).
• Early LVOR sensitivity to translation was significantly reduced in older adults across all target distances.
• Visual target distance modulated LVOR amplitude in both groups, but this effect was diminished in older adults.
• Vestibular catch-up saccades (VCUS) were less frequent in older individuals.

Conclusions:

• Aging significantly impacts the initial linear vestibulo-ocular reflex by prolonging response latency and reducing early gain.
• Older adults demonstrate impaired visual-otolith interaction, primarily reflected in reduced VCUS.
• These findings highlight age-related declines in vestibular function affecting visual-motor control.