A DESCRIPTIVE ANALYSIS OF THE STRUCTURE AND TEMPORAL PATTERN OF VOLUNTARY ETHANOL INTAKE WITHIN AN ACQUISITION PARADIGM

Objective: The present experiment examined the microstructure and temp oral pattern of consummatory behavior to provide insight into the beha vioral processes that regulate the acquisition of voluntary oral ethan ol intake. Method: A microcomputer-controlled data acquisition system was used to dynamically monitor food, water and ethanol intake in Long Evans rats across acquisition of ethanol drinking initiated through t he presentation of a sequence of increasing concentrations of ethanol solutions in a free choice with water. Results: The results showed a b iphasic pattern of ethanol intake as a function of presentation of inc reasing concentrations of ethanol. Total ethanol intake decreased as t he ethanol concentration was increased from 2% to 6%, while, inversely , ethanol intake was significantly increased as the concentration went from 6% to 10%. The initial decrease in ethanol intake, across 2% to 6% ethanol, was a function of decreases in both frequency and size of ethanol bouts. The increase in ethanol intake observed following prese ntation of higher ethanol presentations was solely a function of incre ased size of ethanol bouts. The increased size of ethanol bouts was pa ralleled by an increase in the rate of intake which was not evident ac ross presentation of concentrations below 6%. The pattern of intake ac ross the 23-hour daily sessions exhibited no differences across the da rk/light cycle in ethanol or water intake as the concentrations of eth anol were increased. The results indicated, however, that food intake was characterized by increases in consumption during the first hour fo llowing the presentation of fluids and the night portion of the dark/l ight cycle. Conclusions: The present study revealed, for the first tim e, the involvement of differential, concentration dependent, behaviora l processes in the mediation of the acquisition of voluntary ethanol i ntake.