194 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



which distinctly contradicted this belief, namely, that an injury 

 to the region of the third frontal convolution in man, on the 

 left side, causes a loss of articulate speech (motor aphasia). But 

 this fact, so significant to us now, was not properly valued at 

 the time. The beginning of our modern views of cerebral localiza- 

 tion is found in the work of Fritsch and Hitzig* (1870), in which 

 they exposed and stimulated electrically the cortex cerebri in 

 dogs. They observed that stimulation of certain definite areas, 

 particularly in the sigmoid gyms, gave distinct and constant 

 movements in the limbs, face, etc. (see Fig. 86). This work 

 was followed quickly by experiments of a similar kind made 

 by numerous observers, in which the cerebrum was stimulated in 

 various animals and finally in man. In addition, the method of 

 ablation of these areas was employed with subsequent study of 

 the animal in regard to the motor or sensory defects resulting 

 therefrom, and the results obtained were further extended by 

 careful autopsies upon human beings in whom paralyses of various 

 kinds and sensory defects were associated with more or less defi- 

 nite lesions of the cerebrum. The first outcome of this work was 

 to lead to an extreme view of localization of function in the brain, 

 in which the different motor and sensory areas were definitely 

 circumscribed and separated one from the other, making the 

 cerebrum a plurality of organs, to use Gall's term. The more 

 recent work has tended to modify these extreme views of local- 

 ization and to emphasize the fact that histologically and physio- 

 logically the entire cerebrum is connected so intimately, part to 

 part, that, although the different regions mediate different func- 

 tions, nevertheless an injury or defect in one part may influence 

 to some extent the functional value of all other regions in the 

 organ. The general idea of a localization of function has been 

 accepted, but the modern view is that the cerebrum is com- 

 posed of a plurality of organs, not completely separated one 

 from the other, as taught by Gall, but intimately associated 

 and to a certain extent dependent one on another for their full 

 functional importance. The functional interrelation of different 

 parts of the cortex is shown by the fact that a cortical lesion at one 

 point may involve not only the activity primarily connected with 

 that region, but may influence also the functional performance of 

 far distant uninjured parts of the cortex or even of the underlying 

 portions of the central nervous system, the medulla, and the 

 spinal cord. Monakow states, for example, that in lesions of the 

 pyramidal system we may observe among the temporary symp- 



* Fritsch and Hitzig, "Archiv f. Anatomie und Physiologic und wissea- 

 schaftliche Medizin," 1870, 300. 



