Neural control of vocal pitch production in humans

人们在说话和唱歌时不断地调整声音的音高。声调的调节对于表达意义和情感是至关重要的。例如，在提问过程中，音调升高传达出一种不确定的感觉，而音调下降则传达出一种共识或决心。然而，人们对人类大脑如何控制人们发声时音调的调节知之甚少，因此我对使用脑成像技术研究这一过程很感兴趣，尤其是被称为fMRI或功能性磁共振成像的方法。众所周知，声音的音高是由一组肌肉控制的，这些肌肉会影响声带的张力。当声带紧张时，声音的音高就会升高，当声带放松时，音高就会下降。因此，音高的控制涉及一种推拉机制，在喉部（即声带）的对立肌肉之间，影响声带的张力。研究大脑音高控制的第一步是比较当人们被要求提高或降低他们的声音时大脑的激活模式。是否有单独的大脑区域控制这两个过程？我和我的同事们最近发现了人脑运动皮层的一部分，它控制着喉部的功能，从而控制着音高。对语言和歌曲的神经成像文献的分析表明，这个区域是人类大脑的主要发声中心。在确定了这一区域对声音控制的总体重要性之后，我想进一步探索这一区域，并研究音调是如何通过使系统偏向于音调上升或下降的任务来调节的。这项工作不仅对语言和歌唱有重要意义，而且对语言障碍也有重要意义。许多神经系统疾病，如帕金森氏症或肌萎缩侧索硬化症，对声音有毁灭性的影响。此外，流利障碍，如口吃，被认为有明确的神经基础。因此，对大脑如何控制声音的理解对许多影响声音功能的疾病具有重要的应用价值。

People constantly modulate the pitch of the voice when they speak and when they sing. Modulation of vocal pitch is critical for the expression of meanings and emotions. For example, a rise of pitch, such as during a question, conveys a sense of uncertainty, whereas a drop in pitch conveys a sense of consensus or resolution. However, very little is known about how the human brain controls the modulation of pitch when people vocalize, and so I am interested in investigating this process using brain imaging techniques, most especially the method known as fMRI, or functional magnetic resonance imaging. One thing that is well understood is that the pitch of the voice is controlled by a group of muscles that influence the tension of the vocal cords. When the vocal cords are tensed, the pitch of the voice rises, and when the vocal cords are made to relax, the pitch drops. Hence, the control of vocal pitch involves a kind of push-pull mechanism between opposing muscles in the larynx (i.e., voice box) that affect the tension of the vocal cords. A first step towards examining pitch control in the brain is to compare the patterns of brain activation when people are asked to either raise or lower the pitch of their voice. Are there separate brain areas that control these two processes? My colleagues and I recently identified a part of the motor cortex of the human brain that controls the function of the larynx and hence vocal pitch. An analysis of the neuroimaging literature on speech and song shows that this area is the major vocal centre of the human brain. Having established the general importance of this area for vocal control, I would like to probe this area further and investigate how pitch is regulated by tasks that bias the system towards either rises or falls in pitch. This work has important implications not only for speech and singing but for speech disorders. Many neurological diseases, such as Parkinson's disease or amyotrophic lateral sclerosis, have devastating effects on the voice. In addition, fluency disorders such as stuttering are thought to have a definite neural basis. Therefore, an understanding of how the brain controls the voice has important applications to a host of diseases that affect the functioning of the voice.