114 MARTIN G. LARRABEE AND PAUL HOROWICZ 



brain begins to disappear. So apparently there is something that is different 

 about this glucose perfusion. Incidentally, this same type of thing seems to 

 happen during stimulation of the brain — the metabolism shifts over to a non- 

 carbohydrate type. Geiger, I think, has found this quite definitely and here, 

 again, the effect is quite apparently an irreversible one. There is something 

 being irreversibly destroyed in the brain which is part of the structural integ- 

 rity of the brain. 



In connection with this problem of the function of ATP, there are certainly 

 many difficulties. First, I am curious to know what happens if ATP is going up 

 during anesthesia, or after chlorpromazine? What happens to the phospho- 

 creatine? After all, there is some kind of equilibrium between the phospho- 

 creatine and the ATP. If the phosphocreatine were to go up and the ATP to 

 go down it would be another one of these anomalies. Also, it has been suggested 

 that during increased electrical activity, in the brain, there is a decrease of 

 phosphorylization. Now, it is very possible, as Dr. McElroy pointed out, that 

 there may be some sort of non-phosphorylitic conveyance of electrons, 

 but so far there is no evidence that such a thing happens in the brain. 



Dr. Grenell: I certainly agree with what Dr. Abood says about most of 

 this, but infortunately, I do not know what happens to the phosphocreatine. 

 We are hoping to find out. 



But there is an interesting point that I would like to add. We recently have 

 started to look into what happens with insulin. This is a very confused business, 

 of course, but we did notice that when a cat was injected with enough insulin 

 to put a human being into deep insulin shock, the response to stimulation 

 (direct electrical stimulation on the cortex) increased. Now, perhaps the old 

 story of the EEG flattening out may be true, but the cortical response to an 

 adequate stimulus is another matter. I think if we take our results and compare 

 them with the results that Dr. Magoun obtained not long ago with auditory 

 click responses that they are quite similar. His cortical auditory click response 

 went up in the presence of insulin. Perhaps what one has to think about in the 

 absence of glucose, no matter how you produce it, is that the adequate stimulus 

 for the new threshold is different. The ordinary mechanisms that are producing 

 the spontaneous activity are now shifted over to something else. If we do look 

 to other substrates in the way of fat or protein or what you will, we may find 

 some other story going on here. It is an entirely different story. Actually, if 

 you do shift to an adequate stimulus for the new substrate then your activity 

 picture becomes something else. I am not sure how the ATP values are going 

 to turn out. 



Dr. John Nurnberger (Institute of Living, Hartford, Conn.): I wanted to 

 add just a little to what Dr. Abood has said and to what Dr. Larrabee men- 

 tioned, that is, the possibility that the brain can use a variety of metabolizing 

 agents in addition to glucose. Some of our studies indicate that within 15 min- 



