CHAPTER \< \ 

 CEREBRAL LOCALIZATION 



Of niucli greater practical importance than the experiments in which 

 the entire cerebrum is removed, as described in the lasl chapter, i 

 those in which various parts of it are destroyed or stimulated. Prom 

 the results conclusions may be drawn regarding the important subji 

 of cerebral localization. The effects produced by removal or stimulation 

 different parts of the cerebral cortex vary considerably, some parts of I 

 cortex being set apart for the control of the motor mechanism of the 

 body, others for the reception and interpretation of affer* I stimuli, 

 while others, and these by far the mos1 extensive, are concerned in the 

 correlation or association of the sensory and motor centers. It may 

 !"■ stated in general that: (1) Tim precentral region of the cerebrum 

 contains the centers of higher thought. (2) The ascending frontal con- 

 volution immediately in fronl of the precentral buIcus contains the 

 chief motor centers, a center being distinguishable for each muscular 

 grouping of the body. (3) The postcentral convolution has to do with 

 the centers for the immediate reception of sensory stimuli, the lied 



sensory centers. (4) A large area occupying most of the parietal lobe 

 ami pari of the occipital is undoubtedly associational in its function, 

 since from it do response can be obtained by stimulation, etc. 5 !'• 

 himl this, in the occipital lobe, there is a center having to do with 



reception of visual impulses. (6 In the upper ivolution of the tem- 



poro-sphenoidal lobe, is a similar center for hearing. 



These centers have been differentiated from one another by anatomical. 

 experimental and clinical research. At present we shall confine ourselves 

 to the ' tperimental results. These are obtained by ablation and stimula- 

 tion, and in considering the results it will be convenienl to divide the 

 centers into motor, Bensory, and nonreactr 



ABLATION OF THE MOTOR CENTERS 



Removal of >'»< cortex from the area which controls the movements 

 a definite part of the body say, the arm will l>e found to pi an 



immediate and profound muscular paralysis Th< animal do. 

 the paralyzed extremity for any purpose whatsoever, and yei the mus- 



843 



