Roa Romero Yadira, Senkowski Daniel, Keil Julian
Department of Psychiatry and Psychotherapy, St. Hedwig Hospital, Charité - Universitätsmedizin Berlin, Berlin, Germany
Department of Psychiatry and Psychotherapy, St. Hedwig Hospital, Charité - Universitätsmedizin Berlin, Berlin, Germany.
J Neurophysiol. 2015 Apr 1;113(7):2342-50. doi: 10.1152/jn.00783.2014. Epub 2015 Jan 7.
The McGurk illusion is a prominent example of audiovisual speech perception and the influence that visual stimuli can have on auditory perception. In this illusion, a visual speech stimulus influences the perception of an incongruent auditory stimulus, resulting in a fused novel percept. In this high-density electroencephalography (EEG) study, we were interested in the neural signatures of the subjective percept of the McGurk illusion as a phenomenon of speech-specific multisensory integration. Therefore, we examined the role of cortical oscillations and event-related responses in the perception of congruent and incongruent audiovisual speech. We compared the cortical activity elicited by objectively congruent syllables with incongruent audiovisual stimuli. Importantly, the latter elicited a subjectively congruent percept: the McGurk illusion. We found that early event-related responses (N1) to audiovisual stimuli were reduced during the perception of the McGurk illusion compared with congruent stimuli. Most interestingly, our study showed a stronger poststimulus suppression of beta-band power (13-30 Hz) at short (0-500 ms) and long (500-800 ms) latencies during the perception of the McGurk illusion compared with congruent stimuli. Our study demonstrates that auditory perception is influenced by visual context and that the subsequent formation of a McGurk illusion requires stronger audiovisual integration even at early processing stages. Our results provide evidence that beta-band suppression at early stages reflects stronger stimulus processing in the McGurk illusion. Moreover, stronger late beta-band suppression in McGurk illusion indicates the resolution of incongruent physical audiovisual input and the formation of a coherent, illusory multisensory percept.
麦格克错觉是视听言语感知以及视觉刺激对听觉感知产生影响的一个突出例子。在这种错觉中，视觉言语刺激会影响对不一致听觉刺激的感知，从而产生一种融合的新感知。在这项高密度脑电图（EEG）研究中，我们感兴趣的是麦格克错觉作为一种特定于言语的多感官整合现象的主观感知的神经特征。因此，我们研究了皮层振荡和事件相关反应在一致和不一致视听言语感知中的作用。我们比较了由客观一致的音节与不一致的视听刺激引发的皮层活动。重要的是，后者引发了主观上一致的感知：麦格克错觉。我们发现，与一致刺激相比，在麦格克错觉感知过程中，对视听刺激的早期事件相关反应（N1）有所减少。最有趣的是，我们的研究表明，与一致刺激相比，在麦格克错觉感知过程中，在短潜伏期（0 - 500毫秒）和长潜伏期（500 - 800毫秒）对β波段功率（13 - 30赫兹）有更强的刺激后抑制。我们的研究表明，听觉感知受视觉背景影响，并且随后麦格克错觉的形成即使在早期处理阶段也需要更强的视听整合。我们的结果提供了证据，表明早期阶段的β波段抑制反映了麦格克错觉中更强的刺激处理。此外，麦格克错觉中更强的晚期β波段抑制表明不一致的物理视听输入得到解决，以及形成了连贯的、虚幻的多感官感知。
