The effect of ageing on multisensory integration for the control of movement timing.

Previously, it has been shown that synchronising actions with periodic pacing stimuli are unaffected by ageing. However, synchronisation often requires combining evidence across multiple sources of timing information. We have previously shown the brain integrates multisensory cues to achieve a best estimate of the events in time and subsequently reduces variability in synchronised movements (Elliott et al. in Eur J Neurosci 31(10):1828-1835, 2010). Yet, it is unclear if sensory integration of temporal cues in older adults is degraded and whether this leads to reduced synchronisation performance. Here, we test for age-related changes when synchronising actions to multisensory temporal cues. We compared synchronisation performance between young (N = 15, aged 18-37 years) and older adults (N = 15, aged 63-80 years) using a finger-tapping task to auditory and tactile metronomes presented unimodally and bimodally. We added temporal jitter to the auditory metronome to determine whether participants would integrate auditory and tactile signals, with reduced weighting of the auditory metronome as its reliability decreased under bimodal conditions. We found that older adults matched the performance of young adults when synchronising to an isochronous auditory or tactile metronome. When the temporal regularity of the auditory metronome was reduced, older adults' performance was degraded to a greater extent than the young adults in both unimodal and bimodal conditions. However, proportionally both groups showed similar improvements in synchronisation performance in bimodal conditions compared with the equivalent, auditory-only conditions. We conclude that while older adults become more variable in synchronising to less regular beats, they do not show any deficit in the integration of multisensory temporal cues, suggesting that using multisensory information may help mitigate any deficits in coordinating actions to complex timing cues.