CLARK, G. 
truction of part of the brainnecessary for some function, then some 
other part of the central nervous system can take over that function. 
This is certainly true in your asymmetric lesions, that you can de- 
stroy one side and the other side will take over the functions of 
both sides. 
DR. CLARK: Yes, but with the asymmetric lesions, I think you 
still have really intact tissue; as for complete vicarious functioning 
of the new area, I think we have to see that before we buy it. 
DR. FREEMAN: Well, you can see it in some, say, lesions of a 
sort in the peripheral end of the nervous system. For example, 
recall Sperry's transplant in which he exchanges tendons to differ- 
ent muscles and then forces these monkeys to perform various 
tasks with the tendons reversed. There is indication there that some 
form of reorganization does take place. It is not basically a struc- 
tural modification. That is to say, from all available tests, the 
pattern of nerve organization, anatomically, has not changed, but 
the functional abilities of the animal to use this limb have changed. 
DR. CLARK: That is true, but of course you remember, too, in 
Sperry's spider monkeys that after he moved postcentral gyrus, 
they lost that ability. And his rats never did learn how to use the 
muscles right in their legs, but continued as long as he kept them to 
step harder on a tack. 
DR. FREEMAN: On the other hand, in any form of hi^er, more 
highly organized activity, it is possible to see this sort of thing. For 
instance, Fleuron showed that by reversing nerves supplied to the 
extensor and flexor muscles in the wing, one could alter a bird's 
innervation, but yet the bird could still fly. So some form of re- 
organization obviously takes place. 
DR. CLARK: In the salamander, complete reorganization takes 
place. 
DR. FREEMAN: Well, that is a different story. 
188 
