Somatosensory Basis of Speech Motor Learning

我研究的总体目标是了解大脑感觉和运动区的可塑性及其对人类运动学习的贡献。我的研究使用语音运动学习和人类肢体运动作为实验模型。这项建议中描述的研究侧重于言语，特别是躯体感觉系统中的可塑性在言语运动学习和言语感知中的作用。《目标1》中的研究验证了这样一种假设，即在言语运动学习过程中，躯体感觉系统对大脑感觉运动网络的变化有贡献。这些研究使用机器人设备，在说话过程中选择性地改变体感输入，并测量受试者对这种机械扰动的适应性反应。这项技术与一种新的静息状态神经成像分析相结合，从编码学习的一组区域中识别出哪些功能连接随着学习而得到加强，并且不是网络中其他活动的副产品。我们的初步结果表明，在言语运动学习过程中，躯体感觉系统有助于大脑感觉运动网络的广泛变化。目的2将验证语言运动适应依赖于感觉工作记忆(听觉和躯体感觉)，以及工作记忆中的个体差异预测适应的观点。我们将使用持续的经颅磁刺激，暂时抑制与听觉和躯体工作记忆相关的前额叶皮质区域的活动，以测试其参与言语运动学习的情况。目的3测试的假设是，体感输入与正常情况下与言语产生相类似的感觉输入改变了对言语声音的感知，并揭示了参与言语知觉的躯体皮质网络的存在。为此，我们开发了一种与MR兼容的机器人设备，当参与者在扫描仪中听语音时，该设备可以提供类似语音的面部皮肤变形模式。我们将使用这项技术来测试这样一种想法，即重复配对听觉和体感输入，就像在言语运动学习中发生的那样，有助于大脑的体感区域参与言语感知。

The overall goal of my research is to understand plasticity in both sensory and motor areas of the brain and its contribution to human motor learning. My research uses both speech motor learning and human limb movement as experimental models. The studies described in this proposal focus on speech and specifically on the role of plasticity in the somatosensory system in both speech motor learning and speech perception. The studies in Aim 1 test the hypothesis that the somatosensory system contributes to changes to the brain's sensorimotor network over the course of speech motor learning. These studies use a robotic device that selectively alters somatosensory input during speech and measures subjects' adaptive responses to this mechanical perturbation. This technique is combined with a new resting-state neuroimaging analysis that identifies from among the set of areas that encode learning those whose functional connectivity is both strengthened with learning and are not a by-product of activity elsewhere in the network. Our preliminary results suggest that somatosensory system contributes to extensive changes to the brain's sensorimotor network over the course of speech motor learning. Aim 2 will test the idea that speech motor adaptation relies on sensory working memory (auditory and somatosensory) and that individual differences in working memory predict adaptation. We will transiently suppress activity in a region of pre-frontal cortex associated with auditory and somatic working memory, using continuous theta-burst trans-cranial magnetic stimulation, to test its involvement in speech motor learning. Aim 3 tests the hypothesis that somatosensory inputs comparable to those normally associated with speech production alter the perception of speech sounds and reveal the presence of a somatic cortical network that participates in speech perception. We have developed for this purpose an MR compatible robotic device that delivers speech-like patterns of facial skin deformation as participants listen to speech sounds in the scanner. We will use this technique to test the idea that repeated pairing of auditory and somatosensory inputs, as would occur in speech motor learning, serves to engage somatosensory areas of the brain in speech perception.