STIMULATION OF THE CORTEX CEREBRI. 713 



the reaction time for contraction and for inhibition of skeletal muscle 

 (masseter) was practically the same, namely, 015 second. 



Other Phenomena which result from Stimulation of the Cortex 



Cerebri. 



Besides the movements of voluntary muscles which are provoked by 

 excitation of the motor area of the cortex, and which we shall study in 

 detail in a subsequent section, various other phenomena are observed as 

 the result of such excitation, prominent among these being alterations in 

 the respiration, in the circulatory organs, in the pupil, and in some of the 

 secretions. The probability of the production of such effects is clear 

 from the influence which the emotions are well known to produce 

 upon the various functions in question. 



Influence of the cerebral cortex on respiration. — Danilewsky was 

 the first to make observations upon respiration in this connection. 1 

 On exciting the posterior part of the motor area of the dog, he obtained 

 slowing and increase of amplitude of the movements ; on applying 

 the electrodes to the base of the brain, acceleration was produced. 

 Bochefontaine 2 obtained usually acceleration of respiration. 



Effects upon respiration were obtained by Franck and Pitres 3 on 

 excitation of the motor area only (in the dog), and were not very 

 constant ; sometimes the respirations were slowed, sometimes acceler- 

 ated, sometimes increased in depth, sometimes diminished ; sometimes 

 with a tendency to an inspiratory, sometimes to an expiratory, tone ; 

 the variations, according to them, being due apparently more to the 

 differences in strength of the stimulus than to the part of the motor 

 area to which it was applied. They obtained no results on stimulation 

 of the cortex outside the motor area. Similar results were obtained by 

 v. Bechterew, 4 whereas other observers 5 have described special effects 

 (expiratory or inspiratory) as being obtainable from different and fixed 

 places in the cortex. 



The differences described by these several observers appear to 

 largely depend upon whether the animals were anaesthetised or not, 

 and upon the nature of the anaesthetic. Bichet, 6 using chloralised 

 dogs, found excitation of various points of the cortex, especially of the 

 sigmoid gyrus, to suspend the respiration. 



Connection of the frontal lobe with respiration. — H. Munk 7 

 obtained in the dog, on placing the electrodes at a point on the anterior 

 part of the frontal lobe, arrest of respiration in deep inspiration (often 

 preceded by acceleration), whereas from a point on the under surface of 

 that lobe there was also arrest, but in extreme expiration ; sometimes, 

 however, acceleration. In the monkey, also, stimulation of certain points 

 on the frontal lobe produced either inspiratory or expiratory tetanus. 



1 Arch./, d. yes. Physiol, Bonn, 3875, Bd. xi. S. 128. 

 * Arch, dephysiol. norm, etpath., Paris, 1876, p. 168. 



3 Loc. cit. 



4 "Physiol, d. motor. Hirnrindenregion." 1886; also (with Ostankoii') Neurol. 

 CentralbL, Leipzig, 1894, S. 584. 



5 E.g. Unverricht, Neurol. CentralbL, Leipzig, 1888, S. 274; Preobraschensky, Wien. 

 klin. lf r rhnsrhr., 1890, S. 41-43; Schuchowski, Neurol. CentralbL, Leipzig, 18ns.' S. 1 13. 



H " Circonvolntions centrales,'' These de Paris, 1878. 



7 Munk. VerhamM. d. physiol. Gesellsch. zu Berlin, 1883; and " Funct. d. ( J rosshirn- 

 rinde," 1890, S. 164. 



