Previous studies have suggested that speech motor system mediates suppression by silent lipreading of electromagnetic auditory cortex responses to pure tones at about 100 ms from sound onset. We used sparse sampling functional magnetic resonance imaging (fMRI) at 3 Tesla to map auditory-cortex foci of suppressant effects during silent lipreading and covert self-production. Streams of video clips were presented simultaneously with 1/3 octave noise bursts centered at 250 Hz (low frequency, LF) or 2000 Hz (mid-frequency, MF), or during no auditory stimulation. In different conditions, the subjects were a) to press a button whenever they lipread the face articulate the same consecutive Finnish vowels /a/, /i/, /o/, and /y/, b) covertly selfproducing vowels while viewing still face image, or c) to press a button whenever a circle pictured on top of the lips expanded into oval shape of the same orientation twice in a row. The regions of interest (ROIs) within the superior temporal lobes of each hemisphere were defined by contrasting MF and LF stimulation against silence. Contrasting the nonlinguistic (i.e., expanding circle) vs. linguistic (i.e., lipreading and covert self-production) conditions within these ROIs showed significant suppression of hemodynamic activity to MF sounds in the linguistic condition in left hemisphere first transverse sulcus (FTS) and right hemisphere superior temporal gyrus (STG) lateral to Heschl’s sulcus (HS). These findings suggest that the speech motor system mediates suppression of auditory-cortex processing of non-linguistic sounds during silent lipreading and covert self-production in left hemisphere FST and right hemisphere STG lateral to HS.
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机译:先前的研究表明,语音运动系统通过在声音发生约100毫秒后对纯净音调的电磁听觉皮层响应进行静默唇读来介导抑制。我们在3特斯拉使用稀疏采样功能磁共振成像(fMRI)绘制了无声唇读和隐秘自产过程中抑制效果的听觉皮层病灶图。同时呈现视频剪辑流,并以1/3倍频程噪声突发为中心,突发噪声的中心频率为250 Hz(低频,LF)或2000 Hz(中频,MF),或者在没有听觉刺激的情况下。在不同的条件下,对象是:a)每当他们用唇读面部时都按下一个按钮以发音相同的连续芬兰元音/ a /,/ i /,/ o /和/ y /,b)隐蔽地产生自发元音,同时观察静止面部或c)每当嘴唇上方的圆圈连续两次扩展为相同方向的椭圆形时,按下按钮。通过将MF和LF刺激与静默进行对比,定义了每个半球上颞叶内的感兴趣区域(ROI)。在这些ROI中,非语言条件(即扩大的圆圈)与语言条件(即唇读和隐秘的自我产生)的对比表明,在左半球第一横沟(FTS)和右半球的语言条件下,对MF声音的血流动力学活性有明显的抑制作用半球上颞回(STG)位于赫氏沟(HS)的外侧。这些发现表明,在左半球FST和右半球STG相对于HS侧,无声唇读和隐蔽的自我产生过程中,语音运动系统介导了对非语言声音的听觉皮层处理的抑制。
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