Micturition and defensive behaviors are controlled by distinct neural networks within the dorsal periaqueductal gray and deep gray layer of the superior colliculus of the rat

Electrical stimulation of the dorsal periaqueductal gray (DPAG) or the deep gray layer of the superior colliculus (DGSC) of rats placed in an open-fie ld elicited either a display of tense immobility, accompanied by exophthalm us and/or defecation and micturition, or running and jumping responses. Thr eshold curves of each response were obtained for each structure by the logi stic fitting of accumulated response frequencies. DPAG and DGSC threshold c urves were compared by likelihood-ratio coincidence tests. The output of mi cturition was significantly higher following the stimulation of DPAG (P < 0 .0005). In contrast, no differences were found for the remaining responses. These data support previous studies in anaesthetized cats suggesting the c ritical involvement of DPAG in the control of micturition. Furthermore,they also suggest that topographically distinct neural networks within the DPAG and DGSC control micturition and the other defensive behaviors. (C) 2000 E lsevier Science Ireland Ltd. All rights reserved.