Department of Neurology, University Hospital, Ludwig-Maximilian University Munich, Marchioninistraße 15, 81377, München, Germany.
Graduate School of Systemic Neuroscience, Ludwig-Maximilian University Munich, Munich, Germany.
J Neurol. 2017 Oct;264(Suppl 1):55-62. doi: 10.1007/s00415-017-8453-8. Epub 2017 Mar 18.
MRI diffusion tensor imaging tractography was performed on the bilateral vestibular brainstem pathways, which run from the vestibular nuclei via the paramedian and posterolateral thalamic subnuclei to the parieto-insular vestibular cortex. Twenty-one right-handed healthy subjects participated. Quantitative analysis revealed a rope-ladder-like system of vestibular pathways in the brainstem with crossings at pontine and mesencephalic levels. Three structural types of right-left fiber distributions could be delineated: (1) evenly distributed pathways at the lower pontine level from the vestibular nuclei to the pontine crossing, (2) a moderate, pontomesencephalic right-sided lateralization between the pontine and mesencephalic crossings, and (3) a further increase of the right-sided lateralization above the mesencephalic crossing leading to the thalamic vestibular subnuclei. The increasing lateralization along the brainstem was the result of an asymmetric number of pontine and mesencephalic crossing fibers which was higher for left-to-right crossings. The dominance of the right vestibular meso-diencephalic circuitry in right-handers corresponds to the right-hemispheric dominance of the vestibular cortical network. The structural asymmetry apparent in the upper brainstem might be interpreted in relation to the different functions of the vestibular system depending on their anatomical level: a symmetrical sensorimotor reflex control of eye, head, and body mediated by the lower brainstem; a lateralized right-sided upper brainstem-thalamic function as part of the dominant right-sided cortical/subcortical vestibular system that enables a global percept of body motion and orientation in space.
磁共振弥散张量成像示踪双侧前庭脑桥径路，其始于前庭核，经旁正中及丘脑后外侧亚核，止于顶岛前庭皮质。21 名右利手健康受试者参与了研究。定量分析显示脑桥水平的前庭径路呈绳梯样系统，在Pontine 和中脑水平存在交叉。可以描绘出三种左右纤维分布的结构类型：（1）从前庭核至Pontine 交叉点的较低Pontine 水平上均匀分布的径路；（2）Pontine 和中脑交叉点之间有中等程度的右侧偏侧化；（3）在中脑交叉点之上进一步增加右侧偏侧化，导致丘脑前庭亚核。沿脑干的偏侧化增加是由于Pontine 和中脑交叉纤维的数量不对称，左侧至右侧交叉的纤维数量更高。右利手者右侧前庭中脑电路的优势与前庭皮质网络的右半球优势相对应。在上脑干中出现的结构不对称可能与前庭系统的不同功能有关，这些功能取决于其解剖水平：由较低脑干介导的眼、头和身体的对称感觉运动反射控制；作为占主导地位的右侧皮质/皮质下前庭系统的一部分，右侧上脑干-丘脑功能的偏侧化，使身体运动和在空间中的方向的整体感知成为可能。
