284 ORIGINAL ARTICLES AND CLINICAL CASES 



facilitation of the areas. Voluntary movements are possible in the 

 absence of the motor areas ; there is not conclusive evidence that they 

 function directly in habit ; the phenomena of cerebral paralysis can 

 be explained on the assumption that the motor area is postural and 

 facilitating in function ; there is clear evidence that the analogous 

 structures in lower forms are not directly concerned with the per- 

 formance of learned activities. Although not conclusive, these con- 

 siderations seem sufficient to cast doubt upon the accepted explanation 

 of the function of the motor cortex, and to demand further experimental 

 investigation before we can conclude that the pyramidal tracts form 

 the efferent path for impulses to voluntary movements. 



Summary. 



It has been shown that the albino rat is able to acquire soma?sthetic- 

 motor habits after destruction of the electro-stimulable cortex and the 

 caudate nucleus. Visuo-motor and simple somsesthetic-motor habits 

 which are acquired before the operation are retained after the destruc- 

 tion of these structures and probably after the section of occipito- 

 lenticular fibres. It is clear, therefore, that neither the cerebral- 

 motor areas nor the subcortical nuclei are directly concerned with the 

 performance of learned activities. 



Combined destruction of the motor area and the caudate nucleus 

 results in relatively permanent motor disturbances resembling hemi- 

 plegia in monkeys. Evidence is given that the difficulty is primarily 

 in assuming new attitudes, and it is suggested that the primary func 

 tion of the cerebral motor structures in the rat is the regulation of 

 postural reflexes. Existing evidence does not seem to exclude such an 

 explanation of the function of the stimulable cortex, even in man. 



REFERENCES. 



[1] Bechtebew, W. v. " Die Funktionen der Nervencentra," Jena, 1908. 



[2] Beodmann, K. " Vergleichende Lokalisationslehre der Grosshirnrinde," Leipzig, 1909. 



[3] Brown, T. G. " The Motor Activation of Parts of the Cerebral Cortex other than those 



included in the so-called ■ Motor ' Areas in Monkeys, with a Note on the Theory of 



Cortical Localization of Function," Quart. Jotirn. Exp. Physiol., 1916, 10, 103-144. 

 [4] Carville, C, et Duret, H. " Sur les fonctions des hemispheres cerebraux," Archives 



de Physiol, 1875, 7,352-490. 

 [5] Fritsch, G. , and Hitzig, E. " Ueber die elektrische Erregbarkeit des Grosshirns, 



Arch. f. Anat. u. Physiol., Jahrg. 1870, 300-332. 

 [6] Gierlich, N. " Ueber Symptomatologie, Wesen und Therapie der hemiplegischen 



Lahmung," Wiesbaden, 1913. 

 [7] Gor/rz, F. "Ueber die Verrichtungen des Grosshirns," Arch. f. d. ges. Physiol, 1881, 



26, 1-49. 



