Subjective straight-ahead during neck muscle vibration: effects of ageing.

The subjective visual straight-ahead (SVA) was measured psychophysically before and during unilateral vibration of the posterior neck muscles in order to determine the particular contribution of neck muscle spindles to the perception of body orientation during ageing. We found a symmetrical increase of the vibration-induced displacement of the SVA with advancing age (R = +0.73, p < 0.01, n = 60) in 30 healthy subjects of different ages (range 20-81 years). These data indicate the cervical proprioceptive contribution to multisensory body orientation increases with ageing. One possible interpretation is that the sensorial weight of proprioception increases as the peripheral vestibular input decreases with advancing age, thereby substituting for the lack of vestibular function.