Tourville Jason A, Nieto-Castañón Alfonso, Heyne Matthias, Guenther Frank H
Department of Speech, Language, and Hearing Sciences, Boston University, MA.
Department of Biomedical Engineering, Boston University, MA.
J Speech Lang Hear Res. 2019 Aug 29;62(8S):3055-3070. doi: 10.1044/2019_JSLHR-S-CSMC7-18-0442.
Neuroimaging has revealed a core network of cortical regions that contribute to speech production, but the functional organization of this network remains poorly understood. Purpose We describe efforts to identify reliable boundaries around functionally homogenous regions within the cortical speech motor control network in order to improve the sensitivity of functional magnetic resonance imaging (fMRI) analyses of speech production and thus improve our understanding of the functional organization of speech production in the brain. Method We used a bottom-up, data-driven approach by pooling data from 12 previously conducted fMRI studies of speech production involving the production of monosyllabic and bisyllabic words and pseudowords that ranged from single vowels and consonant-vowel pairs to short sentences (163 scanning sessions, 136 unique participants, 39 different speech conditions). After preprocessing all data through the same pipeline and registering individual contrast maps to a common surface space, hierarchical clustering was applied to contrast maps randomly sampled from the pooled data set in order to identify consistent functional boundaries across subjects and tasks. Boundary completion was achieved by applying adaptive smoothing and watershed segmentation to the thresholded population-level boundary map. Hierarchical clustering was applied to the mean within-functional region of interest (fROI) response to identify networks of fROIs that respond similarly during speech. Results We identified highly reliable functional boundaries across the cortical areas involved in speech production. Boundary completion resulted in 117 fROIs in the left hemisphere and 109 in the right hemisphere. Clustering of the mean within-fROI response revealed a core sensorimotor network flanked by a speech motor planning network. The majority of the left inferior frontal gyrus clustered with the visual word form area and brain regions (e.g., anterior insula, dorsal anterior cingulate) associated with detecting salient sensory inputs and choosing the appropriate action. Conclusion The fROIs provide insight into the organization of the speech production network and a valuable tool for studying speech production in the brain by improving within-group and between-groups comparisons of speech-related brain activity. Supplemental Material https://doi.org/10.23641/asha.9402674.
神经影像学已经揭示了一个对言语产生有贡献的皮质区域核心网络，但该网络的功能组织仍知之甚少。目的 我们描述了为识别皮质言语运动控制网络内功能同质区域周围可靠边界所做的努力，以提高对言语产生进行功能磁共振成像（fMRI）分析的敏感性，从而增进我们对大脑中言语产生功能组织的理解。方法 我们采用了一种自下而上、数据驱动的方法，汇总了之前12项关于言语产生的fMRI研究的数据，这些研究涉及单音节和双音节单词以及伪词的产生，范围从单个元音和辅音 - 元音对到短句（163次扫描会话，136名独特参与者，39种不同言语条件）。在通过相同流程对所有数据进行预处理并将个体对比图配准到共同表面空间后，对从汇总数据集中随机采样的对比图应用层次聚类，以识别跨受试者和任务的一致功能边界。通过对阈值化的群体水平边界图应用自适应平滑和分水岭分割来实现边界完成。对感兴趣的功能区域（fROI）内的平均反应应用层次聚类，以识别在言语过程中反应相似的fROI网络。结果 我们在参与言语产生的皮质区域中识别出了高度可靠的功能边界。边界完成后，左半球有117个fROI，右半球有109个。fROI内平均反应的聚类揭示了一个核心感觉运动网络，两侧是言语运动规划网络。左额下回的大部分与视觉词形区以及与检测显著感觉输入和选择适当动作相关的脑区（如前岛叶、背侧前扣带回）聚类。结论 fROI为言语产生网络的组织提供了见解，并且通过改善与言语相关的脑活动的组内和组间比较，是研究大脑中言语产生的有价值工具。补充材料 https://doi.org/10.23641/asha.9402674。
