Kelland M D, Asdourian D
Department of Psychology, Wayne State University, Detroit, MI 48202.
Behav Brain Res. 1989 Sep 1;34(3):213-34. doi: 10.1016/s0166-4328(89)80103-2.
The connections of the pedunculopontine tegmental nucleus (PPN) have led us to propose that this structure mediates striatally induced inhibition of muscle activity by directing basal ganglia output to an inhibitory reticulospinal system (nucleus reticularis gigantocellularis and ventralis, nrGi-V). We conducted experiments in order to examine the effects of electrical stimulation of the PPN on the activity of selected neck and shoulder muscles. PPN stimulation at low rates (0.1 Hz) elicited bilateral muscle excitation. As the rate of stimulation was increased (e.g. to 10 Hz), less excitation was observed. Anodal DC current inactivation of the nrGi-V during concurrent 10 Hz PPN stimulation resulted in an augmentation of muscle activity above the levels observed during 10 Hz PPN stimulation alone. PPN stimulation (10 Hz) also profoundly inhibited cortically-induced muscle activity. Further support for our proposal stems from increased baseline activity (0.1 Hz PPN-induced excitation) in animals with ibotenic acid lesions of the PPN as compared to normal animals. Apparently, destruction of the PPN releases the musculature from tonic and/or phasic inhibition. A model is discussed which attempts to account for both the rate-dependent changes in excitation and the inhibition of cortically induced muscle activity.
脚桥被盖核（PPN）的连接情况使我们提出，该结构通过将基底神经节的输出导向抑制性网状脊髓系统（巨细胞网状核和腹侧网状核，nrGi-V），介导纹状体诱导的肌肉活动抑制。我们进行了实验，以研究电刺激PPN对选定的颈部和肩部肌肉活动的影响。以低频率（0.1 Hz）刺激PPN会引起双侧肌肉兴奋。随着刺激频率增加（例如增加到10 Hz），观察到的兴奋减少。在10 Hz PPN刺激同时，对nrGi-V进行阳极直流电灭活，导致肌肉活动增强，超过单独10 Hz PPN刺激时观察到的水平。PPN刺激（10 Hz）也能显著抑制皮质诱导的肌肉活动。与正常动物相比，PPN经鹅膏蕈氨酸损伤的动物基线活动增加（0.1 Hz PPN诱导的兴奋），这进一步支持了我们的观点。显然，PPN的破坏使肌肉组织从紧张性和/或相位性抑制中释放出来。本文讨论了一个模型，该模型试图解释兴奋的频率依赖性变化以及皮质诱导肌肉活动的抑制。
