CEEEBRAL FUNCTION IN LEARNING 121 



ops spontaneously and is probably due to cerebellar or semicir- 

 cular canal trouble. It is possible that the condition in this 

 case was of a similar sort and not due at all to the cerebral lesion. 



In all the certain paretic cases described there was extensive *\ 

 lesion to the stimulable cortex as well as to the corpus striatum. 

 Lesions to the stimulable cortex alone do not produce motor dis- 

 turbance. Does lesion in the corpus striatum produce a paretic 

 condition when the stimulable cortex is intact or do these two 

 structures have an interchangeable function as Luciani ('15) sug- 

 gests? In one case only, number 6 (plate I, figure 6), was any 

 large portion of the stimulable cortex intact. The descriptions 

 of this animal made subsequent to operation record a slight right 

 paresis. This was no longer detectable, however, when training 

 was begun, 30 days after operation. One case can not prove the N 

 point, but it suggests that the motor cortex may be able to com- j 

 pensate completely for the loss of the corpus striatum. 



Bilateral injuries to the corpora striata are not followed by 

 paresis. The spasticity noted in some of the cases (table 10) j 

 may perhaps be ascribed to the bilateral lesion since it appeared 

 in animals having very extensive lesions, but none of these ani- 

 mals was kept long enough to assure that the spasticity was not 

 the result of the general cerebral condition following operation. 

 Moreover, a similar spasticity appeared in animals without lesions 

 in the corpora striata, so that the function of these nuclei in pro- 

 ducing it is questionable. Except for the few cases of spasticity 

 the animals with bilateral injuries to the striate nuclei showed no 

 motor disturbances. They were able to climb actively and 

 showed no such weakness as appeared in hemiparesis. In ani- 

 mals number 10*, 11*, 27*, and 29* the injuries to both striate 

 nuclei were very ex tensive but there is no case in the series in which 

 destruction of both nuclei was as great as that of one in the hemi- 

 paretic animals. It may be that the lack of motor disturbance 

 in these animals is due only to the incomplete destruction of the . 

 nuclei, but in number 29* (plate IV, figure 29*) there is indication^ 

 of a complete section of the anterior two-thirds of the right nu- 

 cleus from the thalamus and in numbers 10*, 11*, 25*, and 27* 

 also the lesions to one or both nuclei were very extensive. 



