Neural control of vocal pitch production in humans

当人们说话和唱歌时，他们会不断地调整音调。音高的调节对于意义和情感的表达至关重要。例如，在提问过程中，音调的上升传达了一种不确定的感觉，而音调的下降传达了一种共识或决心的感觉。然而，人们对人类大脑如何控制发声时的音调调制知之甚少，因此我有兴趣使用大脑成像技术来研究这一过程，尤其是被称为fMRI或功能磁共振成像的方法。众所周知，声音的音调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，声音的音调上升，而当声带放松时，音调下降。因此，声调的控制涉及喉部相对肌肉(即声箱)之间的一种推拉机制，它影响声带的张力。研究大脑音调控制的第一步是比较当人们被要求提高或降低音调时大脑的激活模式。是否有不同的大脑区域控制这两个过程？我和我的同事最近发现了人脑运动皮质的一部分，它控制着喉咙的功能，从而控制着音调。对有关语音和歌曲的神经成像文献的分析表明，这一区域是人脑的主要发声中心。在确立了这一区域对发声控制的一般重要性后，我想进一步探讨这一区域，并研究如何通过使系统偏向于音高上升或下降的任务来调节音高。这项工作不仅对言语和歌唱有重要意义，而且对言语障碍也有重要意义。许多神经系统疾病，如帕金森氏病或肌萎缩侧索硬化症，都会对声音产生毁灭性的影响。此外，口吃等流利性障碍被认为有明确的神经基础。因此，了解大脑是如何控制声音的，对一系列影响声音功能的疾病有着重要的应用。

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.