148 LLOYD M. BEIDLER 



The four major assumptions that are involved are : 



(1) The distribution of central and peripheral connections of the afferent 

 neurons is quasi-random but is partially biased. 



(2) The pattern of chemical sensitivity of a receptor cell is imposed and 

 maintained by chemical " sensitizers " that are derived originally from 

 several gustatory sub-centers and are delivered to the receptor cells in 

 quantities that correspond to the richness of synaptic contacts at each level. 



(3) The degree of stimulation of a receptor by a particular chemical 

 depends on the relative richness of that receptor in appropriate sensitive 

 sites. . Initiation of nerve impulses depends also on the richness of synaptic 

 contacts. 



(4) Unwanted neural activity is rejected by mutual inhibitory action 

 among the several higher-order sub-centers that determine the specific 

 chemical sensitivities of the gustatory system. Activity in such a sub-center 

 is a necessary condition for sensation of a particular quality of taste and/or 

 discriminatory behavior in respect to a particular class of chemical stimuli. 



An interesting feature of this model is its statistical character which makes 

 the overall action independent of the details of the connections of individual 

 afferent neurons or of the exact patterns of sensitivity found for individual 

 neurons. 



