Age-related changes in temporal processing of vestibular stimuli

Abstract

Falls are one of the leading causes of disability in the elderly. Previous research has shown that falls may be related to changes in the temporal integration of multisensory stimuli. This study compared the temporal integration and processing of a vestibular and auditory stimulus in younger and older subjects. The vestibular stimulus consisted of a continuous sinusoidal rotational velocity delivered using a rotational chair and the auditory stimulus consisted of 5 ms of white noise presented dichotically through headphones (both at 0.5 Hz). Simultaneity was defined as perceiving the chair being at its furthest rightward or leftward trajectory at the same moment as the auditory stimulus was perceived in the contralateral ear. The temporal offset of the auditory stimulus was adjusted using a method of constant stimuli so that the auditory stimulus either led or lagged true simultaneity. 15 younger (ages 21–27) and 12 older (ages 63–89) healthy subjects were tested using a two alternative forced choice task to determine at what times they perceived the two stimuli as simultaneous. Younger subjects had a mean temporal binding window of 334 ± 37 ms (mean ± SEM) and a mean point of subjective simultaneity of 83 ± 15 ms. Older subjects had a mean TBW of 556 ± 36 ms and a mean point of subjective simultaneity of 158 ± 27. Both differences were significant indicating that older subjects have a wider temporal range over which they integrate vestibular and auditory stimuli than younger subjects. These findings were consistent upon retesting and were not due to differences in vestibular perception thresholds.