Increased Functional Brain Network Efficiency During Audiovisual Temporal Asynchrony Integration Task in Aging

Abstract

Audiovisual integration significantly changes over the lifespan, but age-related functional connectivity in audiovisual temporal asynchrony integration tasks remains underexplored. In the present study, electroencephalograms (EEGs) of 27 young adults (22–25 years) and 25 old adults (61–76 years) were recorded during an audiovisual temporal asynchrony integration task with seven conditions [auditory (A), visual (V), AV, A50V, A100V, V50A and V100A]. We calculated the phase lag index (PLI)-weighted connectivity networks modulated by the audiovisual tasks and found that the PLI connections showed obvious dynamic changes after stimulus onset. In the theta (4–7 Hz) and alpha (8–13 Hz) bands, the AV and V50A conditions induced stronger functional connections and higher global and local efficiencies, reflecting a stronger audiovisual integration effect, which was attributed to the auditory information arriving at the primary auditory cortex earlier than the visual information reaching the primary visual cortex. Importantly, the functional connectivity and network efficiencies of old adults revealed higher global and local efficiencies and higher degree in both the theta and alpha bands. These larger network efficiencies indicated that old adults might experience more difficulties in attention and cognitive control during the audiovisual integration task with temporal asynchrony than young adults. There were significant associations between network efficiencies and peak time of integration only in young adults. We propose that an audiovisual task with multiple conditions might arouse the appropriate attention in young adults but would lead to a ceiling effect in old adults. Our findings provide new insights into the network topography of old adults during audiovisual integration and highlight higher functional connectivity and network efficiencies due to greater cognitive demand.

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

“…Investigations have illustrated that peripheral resolution declines with age (Anderson and Mcdowell, 1998); therefore, another possible reason for the conflicting conclusions might be the location of the stimuli presented. The delayed AVI effect in older adults compared to that of younger adults was consistent with the findings of numerous previous studies, such as Wu et al (2012), Ren et al (2016), and Wang et al (2017and Wang et al ( , 2018. Colonius et al proposed a "time-windowof-integration model," which proposing that the integration of audiovisual integration includes at least two serial stages: an early afferent stage of peripheral processing (first stage) and a compound stage of converging sub-processes (second stage) (Colonius and Diederich, 2004;Diederich et al, 2008).…”

“…Their audio-visual spatiotemporal perceptual training experiment in healthy older adults showed robust malleability of the aging brain (Yang et al, 2018). Additionally, Wang et al examined aging adaption from the view of functional connectivity during AV processing in older adults using an AV discrimination task, and their results showed that older adults activated stronger connections than younger adults (Wang et al, 2017(Wang et al, , 2018. Furthermore, a similar shift adaptive mechanism during memory tasks in the aging brain has been found (Davis et al, 2007).…”

“…However, studies have reported a higher AVI effect for older adults than for younger adults in AV discrimination tasks (Peiffer et al, 2007;Diederich et al, 2008;Zou et al, 2017), sound-induced flash illusion tasks (Deloss et al, 2013), semantic discrimination tasks (Laurienti et al, 2006), and speech perception tasks (Sekiyama et al, 2014). Researchers have further proposed that enhanced AVI might compensate for the unisensory functional decline by enhancing the activity in original brain regions (Diaconescu et al, 2013;Zou et al, 2017), recruiting additional brain areas (Diaconescu et al, 2013;Wang et al, 2018) or strengthening brain functional connectivity (Wang et al, 2018) in the completion of some cognitive tasks. Aging-related studies have shown that there are distractor-suppression deficits in older individuals (Plude et al, 1994;Kok, 2000;Quigley et al, 2010).…”

Functional Connectivity Changes Across the Spectrum of Subjective Cognitive Decline, Amnestic Mild Cognitive Impairment and Alzheimer’s Disease

“…In the present study, the decrement of multi-scale centrality in the somatomotor network may indicate motor dysfunction and further supports the theory that motor impairment could occur at an early stage of AD, or even precede the onset of the cognitive impairment for AD by a decade and longer (Albers et al, 2015). The previous study has detected an increased functional brain network efficiency during the audiovisual task in aging (Wang et al, 2018a), while there is a negative connection between within-network functional connectivity in the visual network and levels of SCD (Contreras et al, 2017). These results indicate visual network impairment beginning from SCD.…”

The interaction between endogenous GABA, functional connectivity and behavioral flexibility is critically altered with advanced age

“…increased connectivity, and lower sensorimotor performance in older adults, impacting general functionality [11]. Although controversial findings exist, an increased interregional coupling has frequently been observed across imaging methods in older populations during task-free [65, 66] and task-related conditions [67, 68] supporting the hypothesis of age-related dedifferentiation. The question as to whether alterations in GABAergic transmission reflect the cause or the ‘cure’ (i.e.…”