LABORATORY EXPERIMENTS ON THE NERVOUS SYSTEM 677 



Compare this series of frogs with the behavior of the normal frog as 

 regards the following points: a. position; b. spontaneous movements; 

 c. movements in response to stimuli of different types and intensities, 

 i.e., electrical, chemical, disturbed position, etc. These notes should be 

 carefully tabulated and reported. 



7. The Decerebrate Pigeon. Observe the behavior of a young pigeon, 

 then remove the entire cerebral cortex. The operation must be done 

 aseptically under ether and Moo grain of atropine. Scoop the cortex 

 out with care not to injure the brain ganglia, optic lobes and tracts. 

 Control bleeding by hot tampons. Close the wound aseptically. 



Keep the animal for several weeks, feeding and watering by placing food 

 in the back of the mouth. Healing will quickly occur and the animal 

 will show certain normal behaviors from the moment it recovers from 

 ether. Examine: 



a. Its spontaneous activity. 



b. Its ability to take feed, swallow, etc. 



c. Its responses to light, mechanical and other stimuli. 



d. Its ability to balance on a perch and in the air. 



e. Any daily improvement in its reactivity. 



8. Stimulation of the Cerebral Cortex in the Dog or Cat. Sensory and 

 motor localizations of the cortex of the mammal have been described for 

 certain areas. Under chloral and ether anesthesia expose the anterior 

 surface of the cerebral hemisphere of the dog. Identify the crucial 

 fissure. Stimulate points anterior, lateral and posterior to this fissure, 

 recording and labeling the exact points on a map prepared for the purpose. 

 Keep records of all muscular reactions. Areas can be identified which on 

 stimulation produce contractions of muscles of the fore leg, of the hind leg, 

 or of various parts of the trunk and tail, etc., verify such areas. Stimulate 

 for short periods only. Avoid fatigue and protect the area from cooling. 

 Especial care must be given to the degree of anesthesia. 



9. Spinal Transection and Motor Control. Under chloral and ether 

 and with aseptic technic transect the spinal cord of a female dog at the 

 level of the thirteenth dorsal. Aseptically close the wound and take 

 hospital care of the animal while it is under observation. 



a. All voluntary movements of the hind legs and pelvic musculature 

 cease. It may be necessary to support the hind quarters. 



b. Certain reflexes still take place through the isolated lumbar seg- 

 ments of the cord, for example, micturition and defecation. 



c. Vasomotor control is at first lost, but is slowly regained in a few 

 days. 



10. Spinal Hemisection. Expose the spinal cord under chloral and 

 ether. Carefully hemisect the right half of the cord in the twelfth seg- 

 ment and close as in the preceding test. Use surgical and aseptic technic. 



a. Carefully map the area and degree of analgesia. 



