Nasir Sazzad M, Ostry David J
McGill University, Montreal, Québec, Canada.
Curr Biol. 2006 Oct 10;16(19):1918-23. doi: 10.1016/j.cub.2006.07.069.
Speech production is dependent on both auditory and somatosensory feedback. Although audition may appear to be the dominant sensory modality in speech production, somatosensory information plays a role that extends from brainstem responses to cortical control. Accordingly, the motor commands that underlie speech movements may have somatosensory as well as auditory goals. Here we provide evidence that, independent of the acoustics, somatosensory information is central to achieving the precision requirements of speech movements. We were able to dissociate auditory and somatosensory feedback by using a robotic device that altered the jaw's motion path, and hence proprioception, without affecting speech acoustics. The loads were designed to target either the consonant- or vowel-related portion of an utterance because these are the major sound categories in speech. We found that, even in the absence of any effect on the acoustics, with learning subjects corrected to an equal extent for both kinds of loads. This finding suggests that there are comparable somatosensory precision requirements for both kinds of speech sounds. We provide experimental evidence that the neural control of stiffness or impedance--the resistance to displacement--provides for somatosensory precision in speech production.
言语产生依赖于听觉和躯体感觉反馈。尽管听觉在言语产生中似乎是主导性的感觉模态，但躯体感觉信息发挥着从脑干反应到皮层控制的作用。因此，构成言语运动基础的运动指令可能既有听觉目标也有躯体感觉目标。在此我们提供证据表明，独立于声学因素之外，躯体感觉信息对于实现言语运动的精确性要求至关重要。我们通过使用一种机器人装置来分离听觉和躯体感觉反馈，该装置改变了下颌的运动路径，从而改变本体感觉，而不影响言语声学。负载的设计旨在针对话语中与辅音或元音相关的部分，因为这些是言语中的主要声音类别。我们发现，即使在对声学没有任何影响的情况下，随着学习，受试者对两种负载的校正程度相同。这一发现表明，两种语音都有类似的躯体感觉精确性要求。我们提供实验证据表明，对刚度或阻抗（对位移的阻力）的神经控制为言语产生中的躯体感觉精确性提供了保障。
