Luo P, Dessem D
Department of Physiology, University of Maryland Dental School, Baltimore, Maryland 21201-1586, USA.
J Comp Neurol. 1995 Feb 27;353(1):50-66. doi: 10.1002/cne.903530107.
Projections from physiologically identified jaw-muscle spindle afferents onto trigeminothalamic neurons were studied in the rat. Trigeminothalamic neurons were identified by means of retrograde transport of horseradish peroxidase from the ventroposteromedial nucleus of the thalamus. Labeled neurons were found contralaterally in the supratrigeminal region (Vsup), the trigeminal principal sensory nucleus, the ventrolateral part of the trigeminal subnucleus oralis, the spinal trigeminal subnuclei interpolaris and caudalis, the reticular formation, and an area ventral to the trigeminal motor nucleus (Vmo) and medial to the trigeminal principal sensory nucleus (AVM). Jaw-muscle spindle afferents were physiologically identified by their increased firing during stretching of the jaw muscles and intracellularly injected with biotinamide. Axon collaterals and boutons from jaw-muscle spindle afferents were found in Vmo; Vsup; the dorsomedial part of the trigeminal principal sensory nucleus (Vpdm); the dorsomedial part of the spinal trigeminal subnuclei oralis, interpolaris (Vidm) and caudalis; the parvicellular reticular formation (PCRt); and the mesencephalic trigeminal nucleus. Trigeminothalamic neurons in Vsup, Vpdm, Vidm, PCRt, and AVM were associated with axon collaterals and boutons from intracellularly stained jaw-muscle spindle afferents. Trigeminothalamic neurons in Vsup, Vpdm, Vidm, and PCRt were closely apposed by one to 14 intracellularly labeled boutons from jaw-muscle spindle afferents, suggesting a powerful input to some trigeminothalamic neurons. These data demonstrate that muscle length and velocity feedback from jaw-muscle spindle afferents is projected to the contralateral thalamus via multiple regions of the trigeminal system and implicates these pathways in the projection of trigeminal proprioceptive information to the cerebral cortex.
在大鼠中研究了从生理上确定的颌肌梭传入纤维到三叉丘脑神经元的投射。通过辣根过氧化物酶从丘脑腹后内侧核的逆行运输来鉴定三叉丘脑神经元。在对侧的三叉上区（Vsup）、三叉神经主感觉核、三叉神经口侧亚核的腹外侧部分、三叉神经脊髓亚核极间部和尾侧部、网状结构以及三叉神经运动核（Vmo）腹侧和三叉神经主感觉核内侧（AVM）区域发现了标记神经元。通过在颌肌伸展时放电增加并细胞内注射生物素酰胺来生理鉴定颌肌梭传入纤维。在Vmo、Vsup、三叉神经主感觉核背内侧部分（Vpdm）、三叉神经脊髓亚核口侧部、极间部（Vidm）和尾侧部的背内侧部分、小细胞网状结构（PCRt）以及中脑三叉神经核中发现了颌肌梭传入纤维的轴突侧支和终扣。Vsup、Vpdm、Vidm、PCRt和AVM中的三叉丘脑神经元与细胞内染色的颌肌梭传入纤维的轴突侧支和终扣相关。Vsup、Vpdm、Vidm和PCRt中的三叉丘脑神经元紧密毗邻来自颌肌梭传入纤维的1至14个细胞内标记终扣，表明对一些三叉丘脑神经元有强大的输入。这些数据表明，颌肌梭传入纤维的肌肉长度和速度反馈通过三叉神经系统的多个区域投射到对侧丘脑，并暗示这些通路在三叉神经本体感觉信息向大脑皮层的投射中起作用。
