FREEMAN, W. J. 
intensity momentarily to a very hi^ level some ten times threshold 
and get what is known techanically as an "orienting reflex", in 
which the animal perked up its ears, sniffed the air, and moved its 
head and eyes as if in search. When this occurred, a rather re- 
markable change in the electrical activity did also, and thereafter, 
for at least two days, the positive effect returned. We again found 
a potentiation of rate of work by stimulation. Subsequently, however, 
this effect disappeared and in its place there came still a third 
phase, in which the rate of work was decreased by stimulation be- 
low the non-stimulus periods. Something happened that impaired 
the response; the same stimulus which still doubled the electrical 
activity and amplitude was associated with a decrease in rate of 
work. 
Still more complicated was the fact that the animal could be 
trained to perceive this stimulus, so that unless the stimulus was 
present, it would not pull at all. We could also train it to press a 
lever to get milk or perform any other type of directed activity. 
Furthermore, if the stimulus intensity was increased andthe effect 
tested on work, above a certain level the higher the intensity the 
greater the deficit of work done by the animal, until a point was 
reached at which the animal stopped completely. If this stimulus was 
maintained, there developed a behavioral and electrical seizure. So, 
although the intensity of electrical stimulation was linearly related 
to the amplitude of electrical activity of the cortex, the behavioral 
effects of electrical stimulation were much more complicated. The 
assumption derived from the doctrine of centers, that a correlation 
could be made between electrical amplitude and cortical function, 
was not valid, and the experiment that was based on this turned out 
to be inconclusive. 
AN INCONCLUSIVE EXPERIMENT INVOLVING 
ABLATION 
I have given examples of two experiments, one involving elec- 
trical recording and the other involving electrical stimulation, and 
would like now to give a third example involving lesion-making. I 
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