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The degree of the optic nerve kinking angle was an independent predictor of postoperative improvement, indicating that irreversible damage to the optic nerve may be associated with its kinking at the optic canal orifice.

Several behavioural studies have shown that the interplay between voice and face information in audiovisual speech perception is not universal. Native English speakers (ESs) are influenced by visual mouth movement to a greater degree than native Japanese speakers (JSs) when listening to speech. However, the biological basis of these group differences is unknown. Here, we demonstrate the time-varying processes of group differences in terms of event-related brain potentials (ERP) and eye gaze for audiovisual and audio-only speech perception. On a behavioural level, while congruent mouth movement shortened the ESs’ response time for speech perception, the opposite effect was observed in JSs. Eye-tracking data revealed a gaze bias to the mouth for the ESs but not the JSs, especially before the audio onset. Additionally, the ERP P2 amplitude indicated that ESs processed multisensory speech more efficiently than auditory-only speech; however, the JSs exhibited the opposite pattern. Taken together, the ESs’ early visual attention to the mouth was likely to promote phonetic anticipation, which was not the case for the JSs. These results clearly indicate the impact of language and/or culture on multisensory speech processing, suggesting that linguistic/cultural experiences lead to the development of unique neural systems for audiovisual speech perception.

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According to recent ERP (event-related potentials) studies, the visual speech facilitates the neural processing of auditory speech for speakers of European languages in audiovisual speech perception. We examined whether this visual facilitation is also the case for Japanese speakers for whom the weaker susceptibility of the visual influence has been behaviorally reported. We conducted a cross-linguistic experiment comparing ERPs of Japanese and English language groups (JL and EL) when they were presented with audiovisual congruent as well as audio-only speech stimuli. The temporal facilitation by the additional visual speech was observed only for native speech stimuli, suggesting a role of articulating experiences for early ERP components. For native stimuli, the EL showed sustained visual facilitation for about 300 ms from audio onset. On the other hand, the visual facilitation was limited to the first 100 ms for the JL, and they rather showed a visual inhibitory effect at 300 ms from the audio onset. Thus the type of native language affects neural processing of visual speech in audiovisual speech perception. This inhibition is consistent with behaviorally reported weaker visual influence for the JL.