TASTE STIMULATION AND PREFERENCE BEHAVIOR 



259 



their preference between 0.1 m NaCl and 0.1 m KCl after pre-training on 

 water in the test cages, but in these tests they were not thirsty. All three 

 sodium deficient S's, immediately and relatively continuously, ingested large 

 quantities of 0.1 M NaCl (a mean intake of 44.2 ml at the end of 2 hr) 

 compared to very little KCl (a mean of 0.4 ml). The non-deficient rats 

 took 4.1 ml of NaCl and 0.4 ml of KCl. Thus, the deprivation schedule 

 induced a behaviorally significant NaCl preference. 



15 



5 12 



< 



h- 

 Z 9 



CONTROL NaCl 

 -A- A 



^-A-A-A-A-A-A-/^-A'A-A A\nA-A-^- 



I I I lvv.1 I I 



3 5 7 9 II 13 15 20 30 60 



MINUTES 



90 



120 



Fig. 1. Mean cumulative intake of water and 0.4 m NaCl solutions by control 

 and salt deprived rats. 



The electrophysiological measure from the whole chorda tympani nerve 

 was obtained on a second group of animals (6 controls and 6 experimentals) 

 given the same diets but no behavioral tests which would interfere with their 

 salt deficiency. Our earlier study (Pfaffmann and Bare, 1 950) has sometimes 

 been criticized because the adrenalectomized rats had been maintained on 

 3 per cent NaCl solution from the time of adrenalectomy to recording. 

 The control and experimental diets were identical except that 1 per cent 

 NaCl was added and mixed with the salt-free food. The nerve was exposed 

 in pentobarbital anesthetized animals using our usual ventral approach, 

 which provides a natural moist chamber and maintains the nerve in good 

 condition. For purposes of quantitative comparisons between animals, 



