MECHANISMS OF LEARNING 



183 



ly in visual habits when these are reacquired after de- 

 struction of the visual cortex? 



The normal visual area was destroyed in twelve 

 rats which were then taught the brightness-discrimi- 



FiG. 44. — Composite diagram of the lesions in the first operation of 

 twelve rats which acquired the visual habit subsequent to this operation. 

 The solid black area was destroyed in all. The stippled area was destroyed 

 in one or more. After Lashley. 



Fig. 45. — Composite diagram of second operations performed upon 

 the same rats illustrated in Fig. 44. The visual habit acquired after the 

 first operation was retained after the second operation. After Lashley. 



nation habit. The total extent of the lesions is shown 

 in Figure 44. After the acquisition of the habit a sec- 

 ond operation destroyed various parts of the remain- 

 ing cortex. Each operation in general destroyed about 

 a third of the remaining cortex, and in the aggregate 

 they covered practically all of the neopallium (Fig. 

 45). These animals all retained the habit after the 

 second operation. 



