SUMMARY 16°- 



question of the membrane as an enzyme; the relationship of bonding, membrane 

 effects and activity, etc., etc. 



In general, it appears at this time (early in the development of such 

 approaches to these problems) that reception— at least for the processes of 

 olfaction and taste — is "more nearly biophysical than biochemical." The prob- 

 lem is not yet as clear in the area of photoreception. Here there is the initial 

 photochemical process beyond which little is known from this point of view. 

 It is important, however, as Dr. MacNichol stated, that "dark adaptation 

 takes place in the electrochemical amplifying mechanisms activated by the 

 splitting of the photo-pigment and resulting in the production of the graded 

 slow potential." Basically, we are dealing here with a charged or trigger system 

 which presumably involves biochemical concepts similar to those with which 

 Dr. McElroy has been dealing in the problem of conversion of chemical energy 

 into light energy and vice versa. 



Such considerations lead us to chemical mechanisms of a grosser nature oc- 

 curring within specialized cells. In certain respects there are both decided agree- 

 ments and decided differences of opinion in this area. It appears that we are 

 all agreed that the classical thoughts with regard to the roles of glucose and 

 rates of oxygen consumption must be considerably changed. I might add, as an 

 aside, that this is particularly gratifying to Dr. Davies and myself, when we 

 remember the consternation with which we were met in 1950 when we first 

 reported that glucose withdrawal did not affect the (X) 2 of cerebral cortex— at 

 least over a period of several hours. It is true, however, that lack of effect on 

 rate of oxygen consumption cannot by itself be taken to be equivalent to ab- 

 sence of effects on metabolism. As Dr. McElroy has pointed out, and as our 

 experimental results have shown, many other metabolic factors must be con- 

 sidered—substrate sources and types, electron transfer mechanisms and others. 

 Dr. Larrabee's calculations can be questioned on the basis of the assumption of 

 a P:0 ratio of 3. I should hesitate to conclude from this information that either 

 the energy level is not important or that intracellular chemical reaction sys- 

 tems have not been altered. With the state of our knowledge as it is at the 

 present time there is no reason to believe that functional activity of neural units 

 cannot derive from initial membrane changes associated with subsequent intra- 

 cellular biochemical reactions which, perhaps through effects on high energy 

 phosphate bond production, lead to reversible (or irreversible, in special cases) 

 changes in cell structure and biosynthetic mechanisms. As Dr. Ling put it, ATP 

 would somehow be important for the maintenance of electrical anatomy (trans- 

 port mechanisms, for example). 



In general, then, it remains for the future to close still further the physical 

 and chemical gaps relating membrane structure, breakdown and resynthesis 

 (this last being largely an intracellular biochemical job) with the various phases 

 and properties of neuronal responses. 



