Age-Related Shifts in Theta Oscillatory Activity During Audio-Visual Integration Regardless of Visual Attentional Load

Abstract

Audiovisual integration (AVI) is higher in attended conditions than in unattended conditions. Here, we explore the AVI effect when the attentional recourse is competed by additional visual distractors, and its aging effect using single-and dual-tasks. The results showed the highest AVI effect under single-task-attentional-load condition than under no-and dual-task-attentional-load conditions (all P < 0.05) in both older and younger groups, but the AVI effect was weaker and delayed for older adults compared to younger adults for all attentional-load conditions (all P < 0.05). The non-phase-locked oscillation for AVI analysis illustrated the highest theta and alpha oscillatory activity for single-taskattentional-load condition than for no-and dual-task-attentional-load conditions, and the AVI oscillatory activity mainly occurred in the Cz, CP1 and Oz of older adults but in the Fz, FC1, and Cz of younger adults. The AVI effect was significantly negatively correlated with FC1 (r 2 = 0.1468, P = 0.05) and Cz (r 2 = 0.1447, P = 0.048) theta activity and with Fz (r 2 = 0.1557, P = 0.043), FC1 (r 2 = 0.1042, P = 0.008), and Cz (r 2 = 0.0897, P = 0.010) alpha activity for older adults but not for younger adults in dual task. These results suggested a reduction in AVI ability for peripheral stimuli and a shift in AVI oscillation from anterior to posterior regions in older adults as an adaptive mechanism.

Sustained Auditory Attentional Load Decreases Audiovisual Integration in Older and Younger Adults

“…Similar results were obtained using meaningless auditory/visual stimuli that removed the influence of high-order cognitive speech processes [12]. In the studies by Alsius et al [10,11] and Ren et al [12], rapid serial visual presentation (RSVP) was employed as the secondary task to add to the attentional load, which was simultaneously and temporally presented the AV discrimination task and mainly induced transient visual attention [13]. In contrast to transient attention, in which the participant was occasionally cued to the stimulated location, sustained attention requires one to maintain attention on a specific task over time, which differentially affects information perception [14,15].…”

“…To study the effect of visual attentional load on AVI, Alsius et al instructed participants to conduct the classic McGurk test under low (single task) and high (dual task) attentional load conditions, and both behavioral and EEG results showed decreased AVI under high attentional load conditions than under low attentional load conditions [10,11]. Similar results were obtained using meaningless auditory/visual stimuli that removed the influence of high-order cognitive speech processes [12]. In the studies by Alsius et al [10,11] and Ren et al [12], rapid serial visual presentation (RSVP) was employed as the secondary task to add to the attentional load, which was simultaneously and temporally presented the AV discrimination task and mainly induced transient visual attention [13].…”

Exogenous Bimodal Cues Attenuate Age-Related Audiovisual Integration

“…(2011) , Ren et al. (2016) , and Ren, Li, et al. (2020) .…”

“…In addition, compared with younger adults, the visual acuity was lower and the auditory threshold was higher in older adults ( Cliff et al., 2013 ; Grady, 2009 ; Liu & Yan, 2007 ; Spear, 1993 ), and this deterioration leads to poorer health status and cognitive functional decline in older adults ( Freiherr et al., 2013 ). Although some studies reported a decreased AVI for older adults compared with younger adults ( Mahoney et al., 2011 ; Ren, Li, et al., 2020 ; Ren et al., 2016 , 2018 ; Wu et al., 2012 ) resulting from age-related general cognitive functional decline, numerous studies also found a higher AVI for older adults than for younger adults ( Deloss et al., 2013 ; Laurienti et al., 2006 ; Peiffer et al., 2007 ; Sekiyama et al., 2014 ; Zou et al., 2017 ). Neuroimaging studies further proposed that older adults might recruit new brain networks ( Diaconescu et al., 2013 ; Ren et al., 2018 ; Ren, Li, et al., 2020 ; Ren, Xu, et al., 2020 ) and strengthen global brain connectivity ( Wang et al., 2018 ) during audiovisual information processing, indicating that it is an adaptive mechanism.…”

“…Although some studies reported a decreased AVI for older adults compared with younger adults ( Mahoney et al., 2011 ; Ren, Li, et al., 2020 ; Ren et al., 2016 , 2018 ; Wu et al., 2012 ) resulting from age-related general cognitive functional decline, numerous studies also found a higher AVI for older adults than for younger adults ( Deloss et al., 2013 ; Laurienti et al., 2006 ; Peiffer et al., 2007 ; Sekiyama et al., 2014 ; Zou et al., 2017 ). Neuroimaging studies further proposed that older adults might recruit new brain networks ( Diaconescu et al., 2013 ; Ren et al., 2018 ; Ren, Li, et al., 2020 ; Ren, Xu, et al., 2020 ) and strengthen global brain connectivity ( Wang et al., 2018 ) during audiovisual information processing, indicating that it is an adaptive mechanism. However, with aging, excepting for vision and audition disorders, there are serious attentional deficits ( Kok, 2000 ; Plude et al., 1994 ; Quigley et al., 2010 ; Williams et al., 2016 ), showing that there are distractor suppression deficits in older individuals ( Kok, 2000 ; Plude et al., 1994 ; Quigley et al., 2010 ), and older adults are much more susceptible to irrelevant distractors ( Williams et al., 2016 ).…”