CENTRAL CONTROL OF THE BLADDER 



121 7 



STIMULATION EXPERIMENTS. It is bv iio means certain 

 that all of the central influences on the micturition 

 reflex are revealed by transection experiments which 

 disclose only those which are tonically (continu- 

 ously) active. From stimulation experiments, there is 

 strong likelihood that the paracentral lobule, the 



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INTRAVESICAL VOLUME IN CO. 



FIG. 15. Cystometrograms showing change in micturition 

 reflex when an anterior pontine preparation (ID) is transected 

 a few millimeters caudally (SUB.D). [From Tang& Ruch (32).] 



premotor area, the posterior cingulate gyrus (15), 

 the posterior pyriform cortex and amygdala (13), 

 and even the cerebellum (6) are concerned in vesicle 

 control. In fact, alinost every cerebral and brain- 

 stem structure has been implicated by one author or 

 another. It is significant, in view of the inhibitory 

 role assigned to the cerebral cortex, that strong 

 micturition contractions are readily produced from 

 cortical stimulation. Stimulation experiments de- 

 signed to test the relationship of the various cortical 

 areas to the micturition reflex are yet to be carried 

 out. Such experiments are usually interpreted in 

 terms of tonus. To explore inhibitory functions an 

 excitatory background is required, and the micturi- 

 tion reflex, biu not tonus, provides this. 



Detailed correlation of brain-stem lesions and 

 stimulation experiments (14) will not be attempted 

 since the latter do not reveal areas inhibitory to the 

 micturition reflex, since the significance of the re- 

 sponse is not clear and it is uncertain whether or not 

 descending fibers from a higher level are being 

 stimulated. The last has been well shown by Gross- 

 man & Wang (11). Stimulation of the general region 

 of the septum pellucidum and the medial preoptic 

 area produced micturition-like contraction. When 

 this area was chronically destroyed, the bladder 

 responses to stimulation of the hypothalamus caudal 

 to the lesion, except the region of the Harrington 

 facilitatory area, became much smaller and more 

 poorly sustained. Whether the septal-preoptic area 



FIG. 16. Cystoinetrograms showing 

 that the micturition threshold is higher 

 after supracollicular decrebration than 

 after intercollicular transection (left) or 

 after transhypothalamic transection 

 (right). [From Tang & Ruch (32).] 



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