Fukuda H, Koga T
Department of Physiology, Kawasaki Medical School, Kurashiki, Japan.
J Auton Nerv Syst. 1992 May 15;38(3):177-90. doi: 10.1016/0165-1838(92)90029-g.
To clarify the area of the motor cortex (M1) in dogs, which corresponds to the cortical area participating in voluntary interruption of micturition in humans, the cortical portions related to the external urethral sphincter were first clarified by recording of somato-sensory evoked potentials, and then systematic cortical stimulation was performed in anesthetized and paralyzed dogs. The hypogastric, pelvic and pudendal nerves innervating the lower urinary tract and rectum were severed to eliminate the secondary reflexes. Five foci were recognized in the cortical potentials evoked after stimulation of the pudendal nerve. These foci existed in the sacral (Sacral-S) and hind leg (Leg-S) areas of the somato-sensory cortex (S1), and in the sacral (Sacral-M), hind leg (Leg-M) and trunk (Abd-M) areas of the M1. Stimulation of the three M1 foci, but not the two S1 foci, provoked centrifugal firings of the pudendal urethral branch. The firings disappeared after cutting of the ipsilateral bulbar pyramis. When the M1 foci were stimulated during the micturition reflex, the reflex discharge of a pelvic vesical branch was interrupted concomitantly with firings of the urethral branch. The interruption was still induced after the pyramidotomy. Pulse train stimulation of these M1 foci reset the cycles (about 2 Hz) in the alternative rhythmic firings of the urethral and vesical branches, which are known to be formed in the pontine micturition center [31,32]. These results suggest that the pyramidal cells in the three M1 foci inhibit the pontine micturition center and concomitantly contract the external urethral sphincter through the pyramidal tract. The possible roles of these M1 foci were discussed.
为明确犬运动皮层（M1）中与人类参与自主排尿中断的皮层区域相对应的区域，首先通过体感诱发电位记录明确了与尿道外括约肌相关的皮层部分，然后在麻醉和麻痹的犬身上进行了系统性皮层刺激。切断支配下尿路和直肠的腹下神经、盆神经和阴部神经以消除继发性反射。刺激阴部神经后诱发的皮层电位中识别出五个焦点。这些焦点存在于体感皮层（S1）的骶部（骶部-S）和后肢（腿部-S）区域，以及M1的骶部（骶部-M）、后肢（腿部-M）和躯干（腹部-M）区域。刺激M1的三个焦点而非S1的两个焦点会引发阴部尿道分支的离心性放电。切断同侧延髓锥体后放电消失。在排尿反射期间刺激M1焦点时，盆腔膀胱分支的反射放电会随着尿道分支的放电而同时中断。锥体切断术后仍可诱发这种中断。对这些M1焦点进行脉冲串刺激会重置尿道和膀胱分支交替节律性放电中的周期（约2 Hz），已知这种节律性放电在脑桥排尿中枢形成[31,32]。这些结果表明，三个M1焦点中的锥体细胞通过锥体束抑制脑桥排尿中枢，并同时收缩尿道外括约肌。讨论了这些M1焦点的可能作用。
