VI PREFACE 



been made in our ability to explain observed properties of neurons in the aggre- 

 gate on the basis of the differential biochemistry of the cells involved? Can we 

 discuss the relationships of chemical structures to integrated activity or must 

 new experimental paths be initiated which might be more productive than 

 those now being pursued? It has been apparent for some time that not all cere- 

 bral neuronal groups, for example, behave similarly. At least part of the differ- 

 ential sensitivity of different types of neurons to drugs, anoxia and other en- 

 vironmental factors is related to either quantitative or qualitative differences 

 in the sequence of metabolic reactions that are going on in the various cells. 

 Nonetheless, present evidence forces one to the conclusion that certain under- 

 lying mechanisms of response are common to neurons in a wide variety of cir- 

 cumstances. The questions remain as to the role of biochemical reactions not 

 only in these general responses, but also in the response mechanisms by which 

 groups of neurons communicate with one another and do permit the organisms 

 to be aware and well informed. 



There remains for this symposium one further area which is somewhat more 

 specific — namely, consideration of the physiological membrane. Any under- 

 standing of the various processes involved in nervous excitation devolves ulti- 

 mately upon a model of some sort that represents a membrane. What is the 

 nature of the membrane alteration that permits excitation or depression? In 

 other words, how is molecular orientation in the membrane related to alterations 

 in activity? In some respects this question differs from the others in that it is 

 unlikely that the actual events occurring in the membrane can be determined 

 directly by experimental means; rather, our understanding of such events ap- 

 pears more likely to be deduced from a series of models of greater and greater 

 refinement, incorporating more and more of the phenomena actually observed. 

 Whether there is any possibility of developing a model at present is a question 

 that surely deserves to be examined. In addition, can any statement be made 

 concerning the interrelationships of membrane structure and properties to 

 physical and chemical events within the neuron? These are the fundamental 

 mechanical questions which must be answered before understanding can be 

 reached of the special faculties of neural tissue to receive and store information 

 which can be communicated to and used by the organism in the proper time. 



R. G. Grenell 

 L. J. Mullins 



