Visual–Somatosensory Integration is Linked to Physical Activity Level in Older Adults

Abstract

Studies examining multisensory integration (MSI) in aging consistently demonstrate greater reaction time (RT) facilitation in old compared to young adults, but often fail to determine the utility of MSI. The aim of the current experiment was to further elucidate the utility of MSI in aging by determining its relationship to physical activity level. 147 non-demented older adults (mean age 77 years; 57% fe male) participated. Participants were instructed to make speeded responses to visual, somatosensory, and visual-somatosensory (VS) stimuli. Depending on the magnitude of the individuals' RT facilita tion, participants were classified into a MSI or NO MSI group. Physical activity was assessed using a validated physical activity scale. As predicted, RTs to VS stimuli were significantly shorter than those elicited to constituent unisensory conditions. Multisensory RT facilitation was a significant predictor of total number of physical activity days per month, with individuals in the NO MSI group reporting greater engagement in physical activities compared to those requiring greater RT facilitation.

Visual-Somatosensory Integration in Older Adults: Links to Sensory Functioning

“…1; see also Mahoney et al ., 2015). As in our previous studies, bilateral stimulation for both visual and somatosensory stimulation was presented (Mahoney et al ., 2011, 2014, 2015). The devices were connected to a network control center, which allowed direct control for each device through the testing computer’s parallel port.…”

“…This discovery is congruent with previous studies that demonstrate that larger RT facilitation effects in aging were associated with increased falls, worse balance, and less engagement in physical activities (Mahoney et al ., 2014, 2015). Here significant multisensory RT facilitation effects are once again reported (Laurienti et al ., 2006; Mahoney et al ., 2011, 2014; Peiffer et al ., 2007), but of particular importance, older adults with worse somatosensory sensitivity appear to exhibit significantly larger VS multisensory RT facilitation effects compared to those with intact somatosensory functioning.…”

“…Visual and somatosensory stimuli were delivered through a custom built stimulus generator (Zenometrics, LLC, Peekskill, NY, USA) that consisted of two control boxes, each housing a 15.88 cm diameter blue light emitting diodes (LEDs) and a 30.48 mm × 20.32 mm × 12.70 mm plastic housing containing a vibrator motor with × 0.8G vibration amplitude (Fig. 1; see also Mahoney et al ., 2015). As in our previous studies, bilateral stimulation for both visual and somatosensory stimulation was presented (Mahoney et al ., 2011, 2014, 2015).…”

“…For the RT data, RTs shorter than 100 ms and less than or greater than two standard deviations from the individual mean were treated as outliers. As previously described (Mahoney et al ., 2015), participants were required to maintain response accuracy equal to or better than 70% across all stimulus conditions in order to be included in the analysis. Although this accuracy cut is arbitrary, it was chosen to allow for more individual variability in RTs due to potentially poor visual and somatosensory functioning.…”

“…Mahoney and colleagues have since reported that not all older adults demonstrate the same magnitude of VS integration. In fact, recent findings have indicated that older adults with larger RT facilitation effects manifest worse balance and increased falls (Mahoney et al ., 2014), and maintain lower engagement in physical activities (Mahoney et al ., 2015). Interestingly, other researchers have demonstrated that older adults exhibit difficulty attending to tactile stimulation in the presence of simultaneous visual distractors (Poliakoff et al ., 2006a).…”