334 



HARRY GRUNDFEST 



• •• 



400 500 600 700 



mjj 



Fig. 7. Hyperpolarizing and depolarizing potentials from a cell in fish retina 

 excited by illumination of different wave lengths, but of constant energy. 

 {Above) — Action spectrum by scanning method. {Below) — The responses 

 numbered on the upper traces are individually shown swept out on a time base. 

 Note that the hyperpolarizing and depolarizing potentials appear to counter- 

 balance at the record marked 0, except for a brief initial negative deflection and 

 a terminal positive one. Durations of light flashes, monitored on upper trace, 

 were 03 sec. (From MacNichol and Svaetichin, 1958.) 



alized information from some outside source, transform or transduce it into 

 information digestible by the organism and pass it on to the latter. The other 

 essential feature is[that they pass on the information to nearby cells and thus 

 do not need a conductile component. Since the input of the cell next in hne 

 is electrically inexcitable the receptor cells must secrete some transmitter 

 agent. Thus, their activity need not be and probably is not electrically excit- 

 able. The cell may generate no potential at all (Grundfest, 1957d), it could 

 generate depolarizing potentials as in the taste buds, or hyperpolarizing 

 potentials, or both kinds. Basically therefore these cells function in their 

 capacity as secretory cells, the electrical activity being secondary, and prob- 

 ably contingent upon the type of secretory activity. 



In order to distinguish between the generator potentials in primary neurons 

 which are always depolarizing and associated with spikes and potentials 

 that are produced in sensory receptor cells without production of spikes, 

 Davis has recently suggested (1960) that the latter should be called receptor 



