Audio–visual integration through the parallel visual pathways

Abstract

Audio-visual integration has been shown to be present in a wide range of different conditions, some of which are processed through the dorsal, and others through the ventral visual pathway. Whereas neuroimaging studies have revealed integration-related activity in the brain, there has been no imaging study of the possible role of segregated visual streams in audio-visual integration. We set out to determine how the different visual pathways participate in this communication. We investigated how audio-visual integration can be supported through the dorsal and ventral visual pathways during the double flash illusion. Low-contrast and chromatic isoluminant stimuli were used to drive preferably the dorsal and ventral pathways, respectively. In order to identify the anatomical substrates of the audio-visual interaction in the two conditions, the psychophysical results were correlated with the white matter integrity as measured by diffusion tensor imaging.The psychophysiological data revealed a robust double flash illusion in both conditions. A correlation between the psychophysical results and local fractional anisotropy was found in the occipito-parietal white matter in the low-contrast condition, while a similar correlation was found in the infero-temporal white matter in the chromatic isoluminant condition. Our results indicate that both of the parallel visual pathways may play a role in the audio-visual interaction.

Musicians have enhanced audiovisual multisensory binding: experience-dependent effects in the double-flash illusion

“…Paraskevopoulos et al 2015). However, in musically lay individuals, prior studies have indicated that the likelihood of perceiving the double-flash illusion is highly correlated with white matter connectivity between occipito-parietal regions, the putative ventral/dorsal streams comprising the "what/where" pathways (Kaposvari et al 2015). This suggests that parallel visual channels play an important role in audiovisual interactions and the temporal binding of disparate cues as required by double-flash percepts (Shams et al 2000(Shams et al , 2002.…”

Lateralisation of the white matter microstructure associated with the hemispheric spatial attention dominance

“…The rate of visuo-motor adaptation was related to the microstructure of the superior cerebellar peduncle, a structure containing fibres connecting the cerebellum and premotor cortex [65]. We showed that audio-visual integration correlates with the microstructural integrity of fibres in the ‘where’ and ‘what’ visual pathways in low and high contrast conditions respectively [45]. Motion detection threshold was found to be correlated with the diffusion properties of the fibres connecting frontal and parietal association areas, putative attention related regions [44].…”

“…It was shown that correlation between the individual structural variability and behavioural performance can identify the involved neuroanatomical structures [42]. The microstructural integrity of the white matter as defined by diffusion tensor imaging is capable of revealing the coupling of structure and function [43–45]. Accordingly, Thiebaut de Schotten showed that the relative size of the right superior longitudinal fasciculus is correlated with the behavioural bias on the line-bisection task [46], which results were later replicated by Cazzoli and colleagues [47].…”

Neuroimaging investigations of dorsal stream processing and effects of stimulus synchrony in schizophrenia

“…Recent work examining the ventral and dorsal visual streams in auditory/visual integration suggest that both parallel visual pathways may play a role in the auditory/visual interaction (Kaposvari et al, 2015); however most studies have reported a specific dorsal visual stream deficit in SP (e.g. Butler and Javitt, 2005).…”