Dissociable Effects of Aging and Mild Cognitive Impairment on Bottom-Up Audiovisual Integration

Abstract

Abstract. Effective audiovisual sensory integration involves dynamic changes in functional connectivity between superior temporal sulcus and primary sensory areas. This study examined whether disrupted connectivity in early Alzheimer's disease (AD) produces impaired audiovisual integration under conditions requiring greater corticocortical interactions. Audiovisual speech integration was examined in healthy young adult controls (YC), healthy elderly controls (EC), and patients with amnestic mild cognitive impairment (MCI) using McGurk-type stimuli (providing either congruent or incongruent audiovisual speech information) under conditions differing in the strength of bottom-up support and the degree of top-down lexical asymmetry. All groups accurately identified auditory speech under congruent audiovisual conditions, and displayed high levels of visual bias under strong bottom-up incongruent conditions. Under weak bottom-up incongruent conditions, however, EC and amnestic MCI groups displayed opposite patterns of performance, with enhanced visual bias in the EC group and reduced visual bias in the MCI group relative to the YC group. Moreover, there was no overlap between the EC and MCI groups in individual visual bias scores reflecting the change in audiovisual integration from the strong to the weak stimulus conditions. Top-down lexicality influences on visual biasing were observed only in the MCI patients under weaker bottom-up conditions. Results support a deficit in bottom-up audiovisual integration in early AD attributable to disruptions in corticocortical connectivity. Given that this deficit is not simply an exacerbation of changes associated with healthy aging, tests of audiovisual speech integration may serve as sensitive and specific markers of the earliest cognitive change associated with AD.

Theta oscillations reflect conflict processing in the perception of the McGurk illusion

“…The relevance of this finding must be considered in the context of the large number of studies that have resorted to the McGurk effect to infer properties of the general AV integration process (e.g., Tiippana et al ., ; Alsius et al ., , ; Skipper et al ., ; Soto‐Faraco & Alsius, ; van Wassenhove et al ., ; Bernstein et al ., ; Andersen et al ., ; Nahorna et al ., , or see Alsius et al ., for an extensive review on the studies and the problematic of generalizing properties from the McGurk effect). In addition, quite a few other studies have used the McGurk illusion as a marker for multisensory integration, to infer how this process is affected under certain manipulations, clinical populations (e.g., Festa et al ., ) or throughout development (e.g., McGurk & MacDonald, ; Burnham & Dodd, ). The present result underscores the need to take these differences into account when designing and interpreting results from studies using the McGurk effect as a proxy for the general process of AV integration.…”

“…This effect pushed the boundaries of audiovisual (AV) speech perception and multisensory integration by demonstrating that the influence of visual information on auditory speech perception goes beyond being a complement to the acoustic signal when it is degraded (e.g., Sumby & Pollack, ; Ross et al ., ; Jaekl et al ., ). Since then, the McGurk effect has been used in hundreds of studies to address the behavioral expression and physiological expression of multisensory integration in general and for AV speech integration in particular (Tiippana et al ., ; Alsius et al ., , ; Skipper et al ., ; van Wassenhove et al ., ; Bernstein et al ., ; Andersen et al ., ; Munhall et al ., ; Nahorna et al ., , ; Festa et al ., ).…”

Change in retinal structural anatomy during the preclinical stage of Alzheimer's disease

“…As noted previously, we also administered an audiovisual McGurk task that has recently been described as a potential new marker of early-stage AD [60] . The McGurk effect is a compelling misperception in which discrepant visual and auditory speech information presented simultaneously results in the listener hearing a fused audiovisual speech sound, rather than the veridical auditory sound (e.g.,/ba/auditory + /ga/visual is heard as/da/rather than/ba/) [77] .…”

Differential Contributions of Selective Attention and Sensory Integration to Driving Performance in Healthy Aging and Alzheimer’s Disease

“…Consistent with this view, AD patients behaviorally display deficits in integrating distinct features of stimuli into coherent representations despite intact processing of individual features (Delbeuck et al, 2007; Festa et al, 2005; Festa et al, 2017; Kurylo, Allan, Collins, & Baron, 2003; Lakmache et al, 1998; Parra et al, 2010). Thus, AD patients are impaired at binding features into coherent representations when binding requires cross-cortical interactions (i.e., binding of motion and color information processed in dorsal and ventral visual streams, respectively), but not when binding places lesser demands on such interactions (i.e., binding of motion and luminance information processed within the same dorsal visual stream) (Festa et al, 2005).…”

“…However, AD patients also demonstrate fundamental deficits in sensory integration (Delbeuck, Collette, & Van der Linden, 2007; Festa et al, 2005; Festa, Katz, Ott, Tremont, & Heindel, 2017; Lakmache, Lassonde, Gauthier, Frigon, & Lepore, 1998; Parra, Abrahams, Logie, & Della Sala, 2010) that may both affect performance on selective attention tasks and make unique contributions to driving performance. AD patients are particularly impaired on visual search tasks that require the integration of multiple features in order to identify a target (Foster, Behrmann, & Stuss, 1999; Landy et al, 2015; Paxton et al, 2007; Tales et al, 2002).…”