OPENING ADDRESS 



Lord Adrian 



I KNOW you would all like me to begin by thanking Professor Zotterman, 

 my old friend Yngve, and the Wenner-Gren Center Foundation for inviting 

 us to this Symposium. It is a great privilege for all of us and a particular 

 pleasure for the very few who are old enough to have made our first visit 

 to Stockholm for the Physiological Congress in 1926. That meeting has 

 always been a shining example of what an international congress can be 

 like when it has charming hosts, a beautiful city to stay in, and not too 

 many communications to listen to. 



All these conditions are satisfied at the meeting we are at now and we 

 can expect to go away as we did in 1926 feeling that we had learnt a great 

 deal about our subject in spite of having so much to enjoy outside it. 



But our subject has reached the right stage for serious discussion and 

 we must get down to it. It concerns fundamental problems where physio- 

 logy and psychology meet : in fact we are in one of those borderlands 

 which are the most fertile regions for the scientific advance. 



The physiology of sensation began by comparing the stimulus with the 

 sensory experience in man. It has now been enlarged to take in the inter- 

 vening events, the molecular changes in the receptors and the transmission 

 of information from them to the brain. We have to decide how the events 

 in the environment excite the receptors and how the information is con- 

 veyed when it must show not only the intensity and time course and 

 localization of the stimulus but the special characters which reveal its 

 origin. The information must contain enough data to make the animal 

 react differentially to stimuli which are of the same type and differ only in 

 some specific quality ; and we are concerned at this meeting with a kind 

 of information where quality is extremely important, for we are dealing 

 with the sense organs which signal the quality of the air we breathe and 

 that of the food and drink we propose to swallow. 



With the larger sense organs in vertebrates the general quality of the 

 stimulus would be indicated by the anatomical arrangement of the sensory 

 system which gives each organ a special pathway to the brain. Impulses 

 arriving by way of the optic nerve will imply a change of illumination 

 of the retina (and will produce a visual experience) and impulses in the 

 auditory nerve will imply vibrations of the basilar membrane. 



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