106 



EXPERIMENTAL PHARMACOLOGY 



brain should be seen as shown in Fig. 99. Now allow the 

 anesthesia to become as light as possible without letting 

 the animal come out from under the influence of the ether 

 too much. With the platinum electrodes (medium tetaniz- 

 ing current) begin to stimulate the exposed dura mater at 

 various points. Try to pick out some centers for various 

 muscular movements. Observe Fig. 101. Make careful 



- Longitudinal sukus 



Crucial sukus (Fissure of Rolando) 



I _, 



.Center for the neck muscles. 



center for the extensors &- 

 adductors of the f or el i mo. 



.center for the flexors &- 

 rotation of the fore/imb. 



-center for the hind limb. 



center for the muscles 

 innervated by the facial. 



Fig. 101. Upper surface of a dog's brain. (Modified from Sisson.) 



note of the position of the electrodes for each of these 

 centers and observe closely the extent and strength of the 

 movements produced. Be sure you understand the an- 

 atomy of the nervous paths l>y which these movements are 

 originated and controlled. Now deepen the anesthesia and 

 again stimulate. Is there any change in the response of 



