Centre for Functional MRI of the Brain (FMRIB), Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK.
Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, the Netherlands.
Cereb Cortex. 2020 Nov 3;30(12):6254-6269. doi: 10.1093/cercor/bhaa182.
The representations of the articulators involved in human speech production are organized somatotopically in primary motor cortex. The neural representation of the larynx, however, remains debated. Both a dorsal and a ventral larynx representation have been previously described. It is unknown, however, whether both representations are located in primary motor cortex. Here, we mapped the motor representations of the human larynx using functional magnetic resonance imaging and characterized the cortical microstructure underlying the activated regions. We isolated brain activity related to laryngeal activity during vocalization while controlling for breathing. We also mapped the articulators (the lips and tongue) and the hand area. We found two separate activations during vocalization-a dorsal and a ventral larynx representation. Structural and quantitative neuroimaging revealed that myelin content and cortical thickness underlying the dorsal, but not the ventral larynx representation, are similar to those of other primary motor representations. This finding confirms that the dorsal larynx representation is located in primary motor cortex and that the ventral one is not. We further speculate that the location of the ventral larynx representation is in premotor cortex, as seen in other primates. It remains unclear, however, whether and how these two representations differentially contribute to laryngeal motor control.
人类言语产生过程中所涉及的构音器官的代表区域在初级运动皮层中呈躯体定位分布。然而，喉的神经代表仍存在争议。之前已经描述了背侧和腹侧喉代表区。但是，尚不清楚这两个代表区是否都位于初级运动皮层中。在这里，我们使用功能磁共振成像来绘制人类喉的运动代表区，并描述激活区域下的皮质微观结构。我们在控制呼吸的同时，通过发声来分离与喉活动相关的大脑活动。我们还绘制了构音器官（唇和舌）和手部区域的图。我们发现发声时有两个单独的激活区-背侧和腹侧喉代表区。结构和定量神经影像学显示，背侧喉代表区下方的髓鞘含量和皮质厚度与其他主要运动代表区相似，但腹侧喉代表区下方的髓鞘含量和皮质厚度则不同。这一发现证实了背侧喉代表区位于初级运动皮层中，而腹侧喉代表区则不在。我们进一步推测，腹侧喉代表区位于前运动皮层中，就像在其他灵长类动物中一样。但是，尚不清楚这两个代表区是否以及如何对喉运动控制产生差异贡献。
