Is inefficient multisensory processing associated with falls in older people?

Abstract

Although falling is a significant problem for older persons, little is understood about its underlying causes. Spatial cognition and balance maintenance rely on the efficient integration of information across the main senses. We investigated general multisensory efficiency in older persons with a history of falls compared to age- and sensory acuity-matched controls and younger adults using a sound-induced flash illusion. Older fallers were as susceptible to the illusion as age-matched, non-fallers or younger adults at a short delay of 70 ms between the auditory and visual stimuli. Both older adult groups were more susceptible to the illusion at longer SOAs than younger adults. However, with increasing delays between the visual and auditory stimuli, older fallers did not show a decline in the frequency at which the illusion was experienced even with delays of up to 270 ms. We argue that this relatively higher susceptibility to the illusion reflects inefficient audio-visual processing in the central nervous system and has important implications for the diagnosis and rehabilitation of falling in older persons.

Successful balance training is associated with improved multisensory function in fall-prone older adults

“…Moreover, given the known interactions between the main sensory systems and vestibular function (e.g. Lopez et al, 2012), as well as the efficiency by which sensory information is combined in the older brain (Diederich et al, 2008;Setti et al, 2011) these findings suggest the possibility that improving balance control in older adults may also affect multisensory function in general, possibly leading to a reduced risk of falling. The aim of the current study was to assess the impact of improved balance control, and therefore vestibular functioning, on the integration of information across two sensory systems which are important for spatial cognition, namely vision and audition, as measured by susceptibility to the SIFI.…”

“…However, Poliakoff, Ashworth, Lowe, and Spence (2006) reported that when spatially incongruent inputs from different modalities are presented to older adults, then this can result in distractibility and inefficient processing of the target stimulus. More specifically, previous studies have reported that in comparison to healthy older adults, fall-prone older adults are less successful at integrating (Mahoney, Holtzer, & Verghese, 2014;Setti, Burke, Kenny, & Newell, 2011) or re-weighting (Jeka, Allison, & Kiemel, 2010) the relative reliability of information from visual, vestibular and proprioceptive inputs in response to changes in the environment. This inefficient re-weighting across sensory inputs may, in turn, affect postural stability.…”

“…For older adults, perceptual outcomes can be affected by a combination of auditory and visual information even when the delay between these two cross-modal stimuli is large. To investigate whether falling in older adults may be affected by a large window of temporal integration, Setti et al (2011) compared the effect of multisensory inputs on perception in two groups of older adults, those with and without a history of falls, by measuring their susceptibility to the sound-induced flash illusion or SIFI (Shams, Kamitani, & Shimojo, 2000). The illusion is experienced when participants report seeing two visual stimuli in a situation in which only one visual stimulus (a 'flash') is presented with two auditory 'beeps'.…”

“…However, it is unclear whether incremental changes in balance function may also be associated with an older adult's ability to efficiently perceive multisensory inputs. In order to elucidate the link between balance maintenance and multisensory integration we utilised a similar protocol to that previously reported (Setti et al, 2011;Stapleton et al, 2014) and measured the susceptibility of healthy and fallprone older adults to the sound-induced flash illusion prior to and following a five week balance training intervention. Participants assigned to the Intervention group were required to perform two 30-min sessions of balance training per week.…”

Neural correlates of oddball detection in self-motion heading: A high-density event-related potential study of vestibular integration

“…It has been seen recently (Setti et al 2011) that audiovisual multisensory integration is less efficient in older subject who fall compared with older non-fallers. The perception of temporally distinct stimuli as concurrent was seen to happen for considerably longer temporal intervals, manifesting as the incorrect multisensory integration of stimuli separated by 270 ms. At this extended time scale, this could indicate a top-down problem in modulating the cognitive processing of sensory information, rather than a problem of sensory decline, and so the phenomenon may not be specific to audio-visual sensory modalities.…”