LASHLEY— CEREBRAL FUNCTION 253 



parts rather than as an expression of their normal function. On the 

 basis of Brown's work and of clinical evidence, however, Monakow 36a 

 is inclined to minimize the importance of the pyramidal areas for 

 ••voluntary" movement. He suggests that "We must give up or essen- 

 tiallv modify the view that the precentral convolution alone conducts 

 impulses to voluntary movement. It is probable that the pyramidal 

 areas serve less for the execution of voluntary movements than for the 

 inhibition of the kinetic functions of spinal coordination. Their func- 

 tion seems to be in the class of reflex activity." Lashley :JT has 

 reported the survival of visuomotor habits after the complete destruction 

 of the stimulable area and serious injury to the caudate and lenticular 

 nuclei 3S and has suggested that the primary function of the stimulable 

 area is the reflex regulation of postural and kinetic mechanisms. Similar 

 results have since been obtained for the stimulable cortex with problem- 

 box and maze habits. 



Thus we find in the literature claims that the electrostimulable cortex 

 is motor, that it is sensory, that it is sensorimotor, that its motor func- 

 tion is exercised through the storing of images of movement, that it 

 is the final common path for all voluntary movements, and that it is a 

 reflex center not primarily concerned with voluntary activity. 



Much of the literature on the function of the electrostimulable 

 cortex, as on cerebral localization in general, presents an inextricable 

 tangle of physiologic fact and psychologic speculation. The long con- 

 troversy between Goltz, Munk, and Hitzig was largely due to their 

 inability to grasp each other's psychologic theories, and recent progress 

 in psychology tends to invalidate much of the cerebral localization which 

 was based on older conceptions of mental faculties. 



Images have fallen into disrepute, and even the psychologists who 

 still deal with them deny that kinesthetic imagery has any demonstrable 

 relation to the initiation of movement (Thorndike 39 ). The conception 

 of volitional activity is too vague to have any scientific value. At best 

 it represents an indefinite distinction between more or less complexly 

 conditioned activities, and the conception of conditioned reflexes leaves 

 the distinction without significance. The "will" has been largely dis- 

 carded in psychology, although it is still in good standing in neurologic 

 discussions. Such a statement as that the stimulable cortex is not 



36a. Monakow : See footnote 57. 



37. Lashley, K. S. : Studies of Cerebral Function in Learning. The Motor 

 Areas, Brain 44:255-286, 1921. 



38. When these experiments were reported, I believed that the lesions were 

 largely confined to the caudate nuclei. Dr. J. B. Jonhston has since called my 

 attention to the fact that the caudate nucleus in the rat comprises only a 

 narrow median band in the corpus striatum and that the lesions reported actually 

 included a considerable portion of the lenticular nucleus. 



39. Thorndike. E. L. : The Mental Antecedents of Voluntary Movement, J 

 Philos., Psychol, and Sc. Meth. 4:40-42, 1907. 



