Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
J Neurosci. 2010 Feb 3;30(5):1832-8. doi: 10.1523/JNEUROSCI.4274-09.2010.
Trigeminal sensory nuclei that give rise to ascending pathways of vibrissal information are heavily linked by intersubnuclear connections. This is the case, for instance, of the principal trigeminal nucleus, which receives strong inhibitory input from the caudal sector of the interpolaris subnucleus. Because this inhibitory input can gate the relay of sensory messages through the lemniscal pathway, a central issue in vibrissal physiology is how brain regions that project to the interpolaris control the activity of inhibitory cells. In the present study, we examined how corticotrigeminal neurons of the primary and second somatosensory cortical areas control the excitability of interpolaris cells. Results show that these two cortical areas exert a differential control over the excitability of projection cells and intersubnuclear interneurons, and that this control also involves the recruitment of inhibitory cells in the caudalis subnucleus. These results provide a basic circuitry for a mechanism of disinhibition through which the cerebral cortex can control the relay of sensory messages in the lemniscal pathway. It is proposed that top-down control of brainstem circuits is prompted by motor strategies, expectations, and motivational states of the animal.
产生触须信息上行通路的三叉神经感觉核通过核间连接紧密相连。例如，主三叉神经核从间极性亚核的尾侧区域接收强烈的抑制性输入。由于这种抑制性输入可以控制触须感觉信息通过背侧索的传递，触须生理学的一个核心问题是投射到间极性的脑区如何控制抑制性细胞的活动。在本研究中，我们研究了初级和次级体感皮层的皮质三叉神经神经元如何控制间极性细胞的兴奋性。结果表明，这两个皮层区域对投射细胞和核间神经元的兴奋性施加了不同的控制，并且这种控制还涉及到募集尾核亚核中的抑制性细胞。这些结果为一种去抑制机制提供了基本的回路，通过该机制，大脑皮层可以控制背侧索中感觉信息的传递。据推测，大脑对脑干回路的自上而下的控制是由动物的运动策略、期望和动机状态引起的。
