Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston TX 77030, USA.
Neuroimage. 2012 Jan 2;59(1):781-7. doi: 10.1016/j.neuroimage.2011.07.024. Epub 2011 Jul 20.
The McGurk effect is a compelling illusion in which humans perceive mismatched audiovisual speech as a completely different syllable. However, some normal individuals do not experience the illusion, reporting that the stimulus sounds the same with or without visual input. Converging evidence suggests that the left superior temporal sulcus (STS) is critical for audiovisual integration during speech perception. We used blood-oxygen level dependent functional magnetic resonance imaging (BOLD fMRI) to measure brain activity as McGurk perceivers and non-perceivers were presented with congruent audiovisual syllables, McGurk audiovisual syllables, and non-McGurk incongruent syllables. The inferior frontal gyrus showed an effect of stimulus condition (greater responses for incongruent stimuli) but not susceptibility group, while the left auditory cortex showed an effect of susceptibility group (greater response in susceptible individuals) but not stimulus condition. Only one brain region, the left STS, showed a significant effect of both susceptibility and stimulus condition. The amplitude of the response in the left STS was significantly correlated with the likelihood of perceiving the McGurk effect: a weak STS response meant that a subject was less likely to perceive the McGurk effect, while a strong response meant that a subject was more likely to perceive it. These results suggest that the left STS is a key locus for interindividual differences in speech perception.
麦格克效应是一种引人注目的错觉，人类会将不匹配的视听语音感知为完全不同的音节。然而，一些正常个体不会体验到这种错觉，他们报告说，即使没有视觉输入，刺激声音也是一样的。越来越多的证据表明，左侧颞上沟（STS）在听觉-视觉言语感知整合中至关重要。我们使用血氧水平依赖功能磁共振成像（BOLD fMRI）来测量大脑活动，当麦格克感知者和非感知者接收到一致的视听音节、麦格克视听音节和不一致的非麦格克音节时，我们会进行测量。下额前回显示出刺激条件的效应（对不一致刺激的反应更大），但不受易感性组的影响，而左侧听觉皮层显示出易感性组的效应（易感个体的反应更大），但不受刺激条件的影响。只有一个大脑区域，即左侧颞上沟，同时显示出易感性和刺激条件的显著影响。左侧颞上沟的反应幅度与感知麦格克效应的可能性显著相关：较弱的 STS 反应意味着受试者不太可能感知到麦格克效应，而较强的反应则意味着受试者更有可能感知到它。这些结果表明，左侧颞上沟是言语感知个体差异的关键部位。
