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Neural Aspects of Vision 



I. Color Discrimination 



The anatomical and physical features of the eye were described in 

 Chapter 2. That chapter was terminated without a discussion of color 

 discrimination because the latter depends on the action of nerve cells 

 and the central nervous system. In this chapter, the neural mechanisms 

 necessary for vision will be examined in more detail. To review 

 briefly, the retina acts as a "photoneural" transducer converting 

 incoming electromagnetic energy to spike potentials on nerve fibers. 

 The potentials travel along the optic nerve, enter the central nervous 

 system, and eventually reach specific areas of the cerebral cortex. The 

 information is "analyzed" at a series of synapses, both within the retina 

 and within the central nervous system proper. Out of this analysis there 

 are, in some way, created the sensations of color, acuity, brightness, 

 shape, and so forth. (It is assumed that the reader will be familiar with 

 the ideas of Chapters 2, 4, and 5 before studying this one.) 



One step in the over-all process of vision, the photomolecular reactions 

 in the rod and cone cells of the retina, is of extreme importance to an 

 understanding of vision. At the same time, it is not necessary to 

 understand these reactions before discussing the neural aspects of vision. 



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