CEREBRAL LOCALIZATION. 



99 



the anatomist and the physiologist, and their 

 labors have been well repaid. The following 

 account of the experiments of Dr. R. W. Ami- 

 don, of New York, may be of interest. They 

 were based upon the following propositions: 

 1. Marked local variations in the temperature 

 of the cephalic contents may be demonstrated 

 by the use of specially constructed surface- 

 thermometers. 2. Cerebral cortical localiza- 

 tion is now sufficiently far advanced to warrant 

 the assertion that the psycho-motor centers for 

 one half of the body occupy a certain area in 

 the cerebral cortex of the opposite hemisphere. 

 3. Functional activity of an organ implies in- 

 creased blood-supply and tissue-change, and 



ft 



cured to the head by buckles. The desirable 

 points in the subject to be experimented upon 

 are, a well-shaped head, thin hair, well-devel- 

 oped and trained muscles, power of facial ex- 

 pression, especially of unilateral facial move- 

 ments, and the ability to contract individual 

 muscles, and moderate intelligence. A man is 

 preferable to a woman, and a European to an 

 African. 



The arrangements being completed, the sub- 

 ject of the experiments is made to exercise re- 

 peatedly a certain muscle or set of muscles; 

 for example, to move repeatedly the right arm. 

 The thermometer which registers an increase 

 of temperature as a result of the movements is 



FIG. 1. LATERAL VIEW OF THE HUMAN BRAIN, SHOWING ITS LOBES AND FISSURES. (After Ferrier.) 

 F, frontal lobe; P, parietal lobe ; O, occipital lobe ; T, temporo-sphenoidal lobe; S, fissure of Sylvius ; S', horizontal portion; 

 8", ascending portion of the same ; c, sulcus centralis, or fissure of Eolando ; A, anterior central convolution, or ascend- 

 ing frontal; B, posterior central convolution, or ascending parietal ; F,, superior; F 2 , middle; F 3 , inferior frontal con- 

 volution ; /j, superior ; / 2 , inferior frontal sulcus ; / 3 , sulcus praecentralis; P,, superior parietal lobule, or postero-parietal 

 lobule; P 2 , inferior parietal lobule, viz. : P 2 , gyrus supra-marginalis ; P 2 ', gyrus angularis ; p, sulcus intra-parietalis ; 

 c, m, termination of the calloso-marginal fissure ; O 1 first, O 2 second, O 3 third occipital convolutions ; po, parieto-oc- 

 cipital fissure ; o, sulcus occipitalis transversus ; o 2 , sulcus occipitalis longitudinalis inferior ; T x first, T 2 second, T 3 third 

 temporo-sphenoidal convolutions ; t l first, # 2 second temporo-sphenoidal fissures. 



consequent elevation of the temperature of that 

 organ. 4. Willed contraction of muscles pre- 

 supposes an increased activity of the volitional 

 motor-center of those muscles in the cerebral 

 cortex. From this it was natural to make the 

 deduction that voluntary activity in a periph- 

 eral part would cause a rise of temperature in 

 the psycho-motor center for that part, which 

 might be indicated by thermometers applied to 

 the skull over such center. Numbers of self- 

 registering surface-thermometers were applied 

 to the surface of the skull to be tested, by pass- 

 ing them through holes in rubber straps se- 



supposed to be placed over the part of the 

 brain controlling such movements, and in this 

 way the cerebral center for movement of the 

 arm is localized. 



This is but one of the many means of investi- 

 gation which have been employed in the study 

 of this question. A study of Fig. 1 will show 

 the normal arrangement of a human brain as 

 seen from the side ; and Fig. 2 shows what has 

 been accomplished in the way of localization 

 as regards the surface of the organ what is 

 known in anatomy as the gray matter of the 

 cerebral convolutions, or of the cortex. These 



