Thirst motivation associated with the salt arousal of drinking

Abstract

Results represent two additional tests of the thirst deprivation trace hypothesis based upon more complex tasks. Tests are based upon the fact that thirst induced by a moderate dose of hypertonic saline (3.0 mEq of a 15% NaCl solution) injected subcutaneously develops rapidly, remains constant for a relatively long period of time (6–7 hr), and provides an opportunity to measure its facilitation (drive) on performance as a function of time independent of differences in consummatory activity. Data of the first experiment support the hypothesis and demonstrate that the facilitation of a previously learned response to depress a lever and obtain water when thirsty will increase as a function of time following the injection. In the second experiment on maze learning the effect did not appear in either measure, running time, or errors. These results indicate that the facilitatory effect is not a general one for complex measures of behavior but is specific to relatively simple motor responses and represents a motor facilitation component in drive.