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Objective: To detect the functional networks of the red nucleus and substantia nigra during the resting state in normal subjects with functional magnetic resonance imaging (fMRI)., Methods: Sixteen normal subjects were performed resting state fMRI scanning and susceptibility weighted imaging. The function connectivity networks base on seed regions of the red nucleus and substantia nigra were extracted from low frequency fluctuation signal in fMRI data by using a temporal correlation method. Individual functional maps were entered two-tailed one-sample t test to determine brain regions with significant positive correlation to the seeds. The statistic threshold was set at P < 0.001, cluster size>42 (336 mm(3)), cluster connectivity criterion 5 min with Alphasim correction., Results: Brain regions involved in the functional connectivity network of the red nucleus include: dorsal anterior cingutate, supramarginal gyrus, the ventrolateral and the ventromedial nucleus of the thalamus, globus pallidus, dorsal thalamus, hippocampus, substantia nigra, red nucleus, pons, dentate nucleus, vermis; Brain regions involved in the functional connectivity network of the substantia nigra include: anterior cingutate, supramarginal gyrus, globus pallidus, dorsal thalamus, hippocampus, lobus insularis, substantia nigra, red nucleus, pons, dentate nucleus. The distribution of the networks of the red nucleus and substantia nigra presented symmetrical. Although the functional networks of the red nucleus and substantia nigra over lapped largely with each other, the rubral network was slightly different with the nigral network, witch showed strong correlations with more wide-spread striatum and thalamus areas., Conclusion: The functional networks of the red nucleus and substantia nigra reflected strong interplay within the extrapyramidal subcortical system, as well as correlations between some limited cerebral cortices; Functional magnetic resonance imaging is a potential powerful tool to explore the extrapyramidal system.

Using extracellular recording techniques, the effect of excitation of red nucleus (RN) on C-responses of wide dynamic range (WDR) neurons and the roles of RN in the inhibitory effect of spindle afferent activated by succinycholine (SCH) on C-responses of WDR neurons were studied. Stimulation of RN caused a significant reduction of nociceptive responses of WDR neurons, which was significantly attenuated by intravenous cyproheptadine and contralateral lesion of RN. These results suggest that the inhibitory effect on nociceptive responses of WDR neurons caused by RN stimulation was partly mediated by 5-HT and RN plays an important role in analgesia induced by the muscle spindle afferent activity.

The function of red nucleus (RN) was important in motor control. This work was to study whether the RN influenced the effect of EA and the somatosensory afferent system. C-responses of spinal dorsal horn neurons (SDHN) were recorded as nociceptive responses. Electrical stimulation of RN could intensify the inhibitory effect of EA and inhibit nociptive response of SDHN. Naloxone (NX) could completely block that inhibition of RN. The result inferred that the RN can modulate both of somatomotion and somatosense. The endogenous opiate system is involved in the somatosensory modulation of RN.

The spontaneous discharges of neurons in red nucleus (RN) of rats have been recorded with microelectrode. The discharge frequency of most RN neurons was changed by nociceptive electrical stimulation of nervi peronaeus communis or nervi tibialis or by nociceptive mechanical stimulation of tail or hind leg. The electrical activities of the somatic sensory neurons in the nucleus ventralis posterolateralis (VPL) of thalamus and of the visceral sensory neurons in the nucleus anterior and nucleus parafascicularis of thalamus have been recorded. According to the form of response to the peripheral nociceptive stimulation the neurons concerned could be divided into three types: pain-excited, pain-inhibited and pain-nonrelated. Electrical stimulating RN could change the spontaneous discharge frequency of somatic pain-related neurons of VPL and visceral pain-related neurons of nucleus anterior and nucleus parafascicularis, and could inhibit their response to somatic and visceral nociceptive stimulation respectively, but did not have influence on the activity of most pain-nonrelated neurons in VPL. The effects of electrical stimulating RN and microinjecting Ach into RN on the same pain-related neuron in VPL were similar. The experimental results show that RN can receive the somatic afferent impulses, that the excited RN can inhibit the transmission of somatic and visceral nociceptive impulses into the thalamus, and that the analgesic effect of RN is concerned with Ach.

The modulation of red nucleus (RN) to pain sense was researched with the latent period of radiant-heat tail flick of rats as standard of the pain threshold. The pain threshold of tail flick reflex was raised significantly by bilateral injection of glutamic acid into RN. Simultaneous injecting glutamic acid into RN and lidocaine into nucleus raphe magnus (NRM) could attenuate the raising effect of pain threshold of RN. This showed that the activated RN has analgesic effect and the NRM plays an important role in the descending inhibitory pathway of RN. The discharges of neurons in caudal part of nucleus spinalis tract nervi trigemini (cNST) evoked by stimulating nerve alveolaris inferior (nAI) with strong pulse were recorded with microelectrode. The nAI-evoked discharges might be inhibited by stimulating contralateral or ipsilateral RN. The RN inhibitory time course on nAI-evoked discharges were shortened after injecting lidocaine into NRM. This demonstrated that the inhibitory effect of RN on neurons in cNST is mediated by NRM. The electrical stimulation of acupoint "Jiache" could inhibit the pain-evoked discharges of neurons in cNST. The inhibitory time course of electrical acupuncture were prolonged by stimulating RN. This result revealed that the activated RN can strengthen the analgesic effect of acupuncture.