Audiovisual Synchrony in Left-hemisphere Brain-lesioned Individuals with Aphasia

We investigated the ability of 40 left-hemisphere brain-lesioned individuals with various diagnoses of aphasia to temporally synchronize the audio of a spoken word to its congruent video using a maximum-likelihood adaptive psychophysical procedure. We found a statistically significant effect of aphasia type, not explained by lesion volume, on measures of audiovisual (AV) synchrony. Brain-lesioned individuals with no symptoms of aphasia, and those with conduction aphasia performed on the synchrony task more similarly to age-matched neurotypical controls, whereas those with anomic aphasia performed the poorest. In addition, we examined the correlation between this ability and AV integration (fusion) and observed a significant correlation between measures of AV synchrony and fusion. An ROI analysis of stroke lesion maps showed that damage to the left posterior temporal regions adversely affected AV processing, although whole-brain univariate lesion-symptom mapping analyses did not yield any significant results. These findings contribute to a better understanding of the functional relationship between different AV processes in multimodal integration and their underlying cortical networks in the human brain.