2?2 ARCHIVES OF NEUROLOGY AND PSYCHIATRY 



ing to the same conclusion. He states that after removal of the motor 

 centers associative motor reflexes are lost. "With unilateral destruction 

 of the motor region in dogs the associative motor reflex may he elicited 

 in the homolateral fore-leg, but in the contralateral fore-leg the reflexes 

 learned earlier are forever lost and can not be reestablished even after 

 a number of conditioning associations (p. 1551ff.)." Gierlich 30 also 

 supports this view of the exclusive motor function of the stimulable 

 areas. 



In opposition to these results, several writers have reported the 

 acquisition of habits after the destruction of the motor areas or of the 

 pyramidal tracts. Starlinger 31 trained a dog to give his paw after 

 total destruction of both pyramidal tracts. Rothmann 32 observed learn- 

 ing in a rhesus monkey in which one precentral gyrus had been extir- 

 pated and the pyramidal tract of the other had been sectioned in the 

 cervical region. Franz and Lashley 33 and Lashley 34 found learning 

 ability in the rat unaltered by total destruction of the stimulable cortex. 

 This re>ult has been confirmed by Jellinek and Koppanyi. 33 



In the contradiction of evidence here, we must favor the positive 

 results. Failure to learn may be due to any one of a number of factors 

 in addition to specific destruction of tissue, and a single positive case 

 with certain destruction of the motor area is sufficient to discredit any 

 number of negative findings such as are cited by Bechterew and Munk. 

 It seems quite certain that the formation of conditioned motor reflexes 

 is possible in the absence of the electrostimulable cortex, but this fact 

 fails to reveal the normal function of the area in the performance of 

 complex activities. Both Rothmann and Brown 38 seem to believe that 

 in the intact animal the motor areas form the chief centrifugal path for 

 complex adaptive reactions and that when learning occurs in their 

 absence it is to be considered as due to vicarious function of other 



30. Gierlich. X.: Ueber Symptomatologie, YYesen, unci Therapie der hemi- 

 plegischen Lahmung, Wiesbaden, 1913. 



31. Starlinger, J.: Die durchschneidung beider Pyramiden beim Hunde, 

 Neurol. Zentralbl. 14:390-394. 1895. 



32. Rothmann, M. : Ueber die physiologische Wertung der cortico-spinalen 

 (Pyramiden) Balm, Arch. f. Anat. u. Physiol. (Physiol. Abt.) pp. 217-275, 1907. 



33. Franz, S. I., and Lashley, K. S. : The Retention of Habits by the Rat 

 After Destruction of the Frontal Portion of the Cerebrum, Psychobiol 1:3-18 

 1917. 



34. Lashley, K. S. : Studies of Cerebral Function in Learning, Psychobiol. 

 2:55-135, 1920. 



35. Jellinek. A., and Koppanyi, T. : Lernfahigkeit gehirnverletzter Ratten. 

 Anzeiger d. Akad. d. YViss., Wien, 1923, No. 17. 



36. Brown, T. (i.: Studies. XXVII. (>. The Motor Activation of Parts of 

 the Cerebral Cortex Other Than Those Included in the So-Called "Motor" 

 Areas in Monkeys, Quart. J. F.xper. Physiol. 10:103-143, 1916. 



