Effects of age and left hemisphere lesions on audiovisual integration of speech

Benefit of visual speech information for word comprehension in post-stroke aphasia

“…We also found that primary somatosensory cortex (PoCG) and parietal association areas (SMG) mediate the benefit of visual speech information for comprehension. These regions may be engaged in encoding phonological information from mouth movements (Möttönen et al, 2005;Skipper et al, 2005Skipper et al, , 2007 and binding it with the auditory signal (Bernstein et al, 2008;Bernstein & Liebenthal, 2014;Michaelis, 2020). Additionally, we showed that IFG is associated with the benefit of mouth movements, which is in line with Skipper et al (2005; and Watkins et al (2003), but not other recent studies with PWA (Andersen & Starrfelt, 2015;Hickok et al, 2018).…”

“…They found that left posterior superior and middle temporal regions, insula (INS), as well as parts of the occipital cortex, but not the IFG, are associated with audiovisual integration (Hickok et al, 2018). More recently, Michaelis et al (2020) tested audiovisual integration abilities of PWA using asynchronous auditory and visual signals. Lesions to the left supramarginal gyrus (SMG) and planum temporale of the STG were associated with reduced temporal sensitivity to the asynchronous audiovisual signal, indicating that these regions are important for temporal perception that mediates audiovisual integration.…”

“…Notably, and of greater potential relevance to comprehension, PWA also benefit from mouth movements when acoustic and visual speech cues match, e.g., when "pa" is produced both auditorily and visually, relative to when "pa" is produced auditorily only (Andersen & Starrfelt, 2015;Baum et al, 2012;Campbell et al, 1990;Hessler et al, 2012;Hickok et al, 2018;Michaelis, 2020; but see also Youse et al, 2004). However, in a study assessing the ability of individuals with left hemisphere stroke to extract visual speech information, Schmid and Ziegler (2006) showed that PWA did not benefit from audiovisual relative to auditory-only stimuli and were impaired in matching asynchronous stimuli across auditory and visual modalities.…”