Somatotopic direct projections from orofacial areas of secondary somatosensory cortex to trigeminal sensory nuclear complex in rats.
Somatotopic direct projections from orofacial areas of secondary somatosensory cortex to trigeminal sensory nuclear complex in rats.
复制标题
大鼠从次级体感皮层口面部区域到三叉神经感觉核复合体的体位直接投射。
DOI：
10.1016/j.neuroscience.2012.05.065
复制
发表时间：
2012
期刊：
影响因子：
3.3
通讯作者：
A Yoshida
中科院分区：
文献类型：
--
作者：
T Haque;F Akhter;T Kato;F Sato;R Takeda;K Higashiyama;M Moritani;Y-C Bae;BJ Sessle;A Yoshida
关于从次级体感皮层 (S2) 的口面部区域到脑桥和延髓（包括二级体感神经元池）的投射，人们知之甚少。为了在大鼠中解决这个问题，我们首先检查了在将逆行示踪剂氟金（FG）注射到对支配口面部组织的三叉神经的刺激有反应的Vp/Vo中的五个区域后，投射到三叉神经感觉核复合体（TSNC）的三叉神经主核（Vp）或口腔亚核（Vo）的S2神经元的分布。在 S2 背侧区域（口面部 S2 区域）发现了大量 FG 标记的神经元，具有体位排列。通过记录三叉神经刺激引起的皮质表面电位，口面部 S2 区域的体位排列与口面部传入输入的排列紧密匹配。然后，在将顺行示踪剂生物素化右旋糖胺 (BDA) 注射到这些区域后，我们检查了从口面 S2 的这些电生理学定义区域到脑桥和延髓的下降投影的形态。大量 BDA 标记的轴突纤维和末端仅在一些二级体感神经元池中可见，最显着的是在对侧 TSNC 中，尽管在对侧 TSNC 的某些头尾水平（包括三叉神经极间亚核的头尾中间水平）中未看到标记的末端。 TSNC 的投影显示了背腹、浅-深和颈尾方向的体位排列。 Vp/Vo 中的体位排列与 TSNC 中口面三叉神经传入的电生理学定义的中心投影位点密切匹配。目前的结果表明，口面部 S2 选择性地投射到对侧 TSNC 的某些颈尾水平，并且这些投射可能允许口面部 S2 准确地调节口面部体感传输到更高的大脑中心，包括口面部 S2 本身。
Little is known about the projections from the orofacial areas of the secondary somatosensory cortex (S2) to the pons and medulla including the second-order somatosensory neuron pools. To address this in rats, we first examined the distribution of S2 neurons projecting to the trigeminal principal nucleus (Vp) or oral subnucleus (Vo) of the trigeminal sensory nuclear complex (TSNC) after injections of a retrograde tracer, Fluorogold (FG), into five regions in the Vp/Vo which were responsive to stimulation of trigeminal nerves innervating the orofacial tissues. A large number of FG-labeled neurons were found with a somatotopic arrangement in the dorsal areas of S2 (orofacial S2 area). This somatotopic arrangement in the orofacial S2 area was shown to closely match that of the orofacial afferent inputs by recording cortical surface potentials evoked by stimulation of the trigeminal nerves. We then examined the morphology of descending projections from these electrophysiologically defined areas of the orofacial S2 to the pons and medulla after injections of an anterograde tracer, biotinylated dextranamine (BDA), into the areas. A large number of BDA-labeled axon fibers and terminals were seen only in some of the second-order somatosensory neuron pools, most notably in the contralateral TSNC, although the labeled terminals were not seen in certain rostrocaudal levels of the contralateral TSNC including the rostrocaudal middle level of the trigeminal interpolar subnucleus. The projections to the TSNC showed somatotopic arrangements in dorsoventral, superficial-deep and rostrocaudal directions. The somatotopic arrangements in the Vp/Vo closely matched those of the electrophysiologically defined central projection sites of the orofacial trigeminal afferents in the TSNC. The present results suggest that the orofacial S2 projects selectively to certain rostrocaudal levels of the contralateral TSNC, and the projections may allow the orofacial S2 to accurately modulate orofacial somatosensory transmission to higher brain centers including the orofacial S2 itself.