Role of the neural network of the brain stem in the inhibition of the rhythmical jaw movements

已知，对脑干局部区域的电刺激可抑制重复刺激皮质咀嚼区(CMA)所诱发的节律性下颌运动(RJM)。然而，该区域的生理意义尚不清楚。首先，用神经示踪的方法研究了神经网络对兔RJM的抑制作用。抑制区位于中脑导水管周围灰质附近的网状结构。顺行示踪剂生物素或逆行示踪剂荧光金在该区域的注射与抑制作用相一致。在脑桥内侧网状核和桥脑内侧网状核也发现了生物细胞的标记终末。提示中脑导水管周围灰质附近的网状结构与桥脑内侧网状核之间的相互联系可能参与了对RJMS的抑制作用。其次，为了了解皮质诱发RJMS的特点，我们用电生理学和解剖学技术研究了兔CMA的皮质-纹状体通路。从壳核腹侧部记录到刺激CMA的诱发电位。将生物半胱氨酸注射到CMA，标记的终末位于壳核的腹侧。提示壳核腹侧部分可能参与咀嚼运动的控制。

It has been known that electrical stimulation to the focal area in the brain stem inhibits the rhythmical jaw movements (RJMs) evoked by repetitive stimulation to the cortical masticatry area (CMA). However, the physiological significance of that area has not been clarified. First, the neural network involved in the inhibitory effect on the RJMs was investigated in the rabbit using neuro-tracing methods. The inhibitory area was identified in the reticular formation adjacent to the periaqueductal gray matter. Injection of the anterograde tracer biocytine or retrograde tracer fluoro-gold was in this area conformed by the inhibitory effect. Labeled terminals by biocytine were found in the medial pontine reticular nucleus, and labeled cell by fluoro-gold was also found in the medial pontine reticular nucleus. This suggests that the reciprocal connection between the reticular formation adjacent to the periaqueductal gray matter and the medial pontine reticular nucleus may involved in the inhibitory effect on RJMs. Second, in order to know the feature of cortically induced RJMs, we investigated the cortico-striatal pathway from the CMA of the rabbit with electrophysiology and anatomical technique. Evoked potentials by stimulation to the CMA were recorded from the ventral part of the putamen. Injection of biocytine to the CMA resulted in that labeled terminals were located in the ventral part of the putamen. It is suggested that the ventral part of the putamen may involved in the control of masticatory movements.