260 ARCHIVES OF NEUROLOGY AXD PSYCHIATRY 



Right Hemisphere: The lesion was similar to that on the left but slightly 

 more extensive. The cortex within the rolandic fissure was destroyed, and the 

 lesion extended farther over the operculum. 



After destruction of almost all of the arm areas of both sides and 

 of most of the areas of the legs and face, this animal, on recovery from 

 paralysis, showed perfect retention of visual and motor habits acquired 

 before injury. Except for the paralysis and later spasticity, no sig- 

 nificant change in his behavior could be noted. 



Number 2. — This was a small male cebus too wild for training at the begin- 

 ning of the experiments. The motor area of the right hemisphere was exposed, 

 the arm, face and leg areas identified and cauterized to a depth of 5 mm., 

 caudad to central fissure, laterad and cephalad to a line 5 mm. beyond the limits 

 of the excitable area. 



Following operation, the left leg and arm were not used. The leg was 

 hyperextended and gave some support to the body in standing or sitting, but 

 made no stepping movements. No movements of the hand could be elicited. 

 This complete paralysis of the left hand persisted for two weeks. 



Four weeks after operation, the left leg was used almost normally. The left 

 arm could be used to support the animal's weight, but tended to become rigid in 

 hyerpextension, and the left hand could not be used for grasping. 



Eleven weeks after operation, the paralysis had almost disappeared; the 

 left hand was somewhat clumsy but could be used in grasping food. It was 

 not used when the right hand was unrestrained. 



Training on the problem boxes was begun at this stage of recovery. During 

 the next three months, the problems were learned and retention tests given. 



Seven months after the first operation, the left motor area was exposed and 

 similarly explored and destroyed. Paralysis of the right arm and leg followed. It 

 appeared to be as complete as that of the left side following the first lesion. It 

 improved more rapidly, however. Six weeks after operation the right hand was 

 used to pick up food, and, although still somewhat spastic, was judged capable 

 of manipulating the latch boxes. Retention tests were therefore begun. The 

 average time per trial for successive groups of five trials in training, pre- 

 liminary retention tests, and postoperative retention tests are given in Table 2. 

 Visual discrimination was unaffected by the operation. 



Table 2. — Average Time in Seconds Per Trial Consumed in Opening Eaeh 



Problem-Box in Each Day's Practice in Training, Preliminary Retention 



Tests and Postoperative Retention Tests 



* Failed to open box while under observation and was left in the cage over night. 

 + Time with hasp left unfastened. 



