T. 



CHAPTER 

 XI 



NEURAL MECHANISMS OF 

 DECISION MAKING* 



E. Roy John, Ph.D.** 

 GENERAL CONSIDERATIONS ABOUT MEMORY 



HIS paper is largely concerned with the rather specialized 

 decision-making involved when a cat decides which of two previ- 

 ously experienced frequencies of flickering light is being pre- 

 sented. Since the constituent flashes of the two flicker frec[uencies 

 are identical, such decision-making, or differential discrimination, 

 would seem difficult to perform on the basis of the instantaneous 

 quality of the stimulus. In contrast to existential discriminations, 

 based on the presence or absence of a stimulus, differential dis- 

 crimination of this sort logically would seem to require the nervous 

 system to analyze the temporal sequence, or pattern, of stimulation. 

 Although one can conceive of possible alternate niechanisms 

 for the mediation of such behavior by time-measuring devices or 

 filter networks, a plausible mechanism for the analysis of sequential 

 stimuli would be a coincidence detector which compared patterns 

 of incoming activity with patterns generated by a stored representa- 

 tion of previously experienced sequences — a memory. This hy- 

 pothesis, with some relevant electrophysiological evidence, has been 

 presented in detail elsewhere (7, 9). My purpose here is to review 



*The work described in this paper was supported in part by Research Grant 

 MY-2972 from the National Institute of Mental Health, and Grant G21831 from 

 the National Science Foundation. 



**The author takes pleasure in acknowledging the kindness of Marc Weiss for 

 making available the data shown in Figures 6, 7. 8, and 9, and the assistance of Arnold 

 L. Leiman and Anthony L. F. Gorman in acquisition of portions of the data here 

 reported. 



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