1894.] Effect of Excitation of the Cerebrum on Respiration. (51 



III. " The Effect produced upon Respiration by Faradic Excita- 

 tion of the Cerebrum in the Monkey, Dog, Cat, and 

 Rabbit." By W. G. SPENCER, M.S., M.B., Assistant 

 Surgeon to the Westminster Hospital. Communicated 

 by Professor VICTOR HORSLEY, F.R.S. Received De- 

 cember 15, 1893. 



(From the Pathological Laboratory of University College, London.)* 

 (Abstract.) 



The author of the paper brings forward evidence to show that, 

 whilst the effect upon respiration of exciting the cerebrum in a 

 non-ansesthetised animal is probably a complex one, yet, by careful 

 regulation of the anaesthetic state, four constant effects can be ob- 

 tained upon respiration by stimulation of the cortex, and these can be 

 traced down each in a course of its own from the cortex to the 

 medulla oblongata. In the production of the anaesthetic state the 

 author lavs stress not only upon the drug (ether) used, but also upon 

 the following general conditions apncea, loss of blood, exposure of 

 the brain, extravasation of blood, general exhaustion of the animal, and 

 departure from health prior to the experiment. 



The four effects upon respiration obtained in this research are as 

 follows : 



A. Diminution of Action. 



Slowing and Arrest of the Respiratory Rhythm. The cortical area 

 where this result was obtained is situated just outside the olfactory 

 tract in front of the point where the tract joins the temporo- 

 sphenoidal lobe. On exposing successive and vertical sectional 

 surfaces of the hemisphere the same result was obtained by exciting 

 in the line of the strand of fibres known as the olfactory limb of the 

 anterior commissure. After decussating at the anterior commissure, 

 the tract is continued backwards on either side of the infundibulum 

 into the red nucleus below and external to the aqueduct at the plane 

 of exit of the 3rd nerve. 



B. Increased Action. 



1. Acceleration. Commencing from a point on the convex surface 

 of the cortex within the " sensori- motor " area, the effect may be 

 followed back just below the lenticular nucleus where it bordei'S on 

 the outer and ventral portion of the internal capsule ; the strand runs 



* Grants have been made towards the research by the Eoyal Society and by the 

 British Medical Association. 



