Contexts control negative contrast and restrict the expression of flavor preference conditioning

Abstract

Consumption of a high concentration of sucrose can have either a detrimental, negative contrast effect or a facilitatory, preference conditioning effect on subsequent consumption of a low concentration of sucrose, depending on the cues that are present during consumption. The role of context and flavor cues in determining these effects were studied using analysis of the microstructure of licking in mice. Exposure to a high concentration followed by exposure to a low concentration resulted in a transient reduction in mean lick cluster size, which was context dependent (Experiment 1). However, there was no change in the total number of licks or overall consumption. When a flavor that had previously been paired with a high concentration was paired with a low concentration, there was an increase in the total number of licks, and overall consumption, but no change in the mean lick cluster size (Experiment 2). Pairing a high concentration with a flavor in a particular context before pairing the context and flavor compound with a low concentration resulted in abolishing the expression of the flavor preference conditioning effect on the total number of licks and consumption (Experiment 3). These results demonstrate that although context and flavor cues have dissociable effects on licking behavior, their interaction has an antagonistic effect on the behavioral expression of memory.

Figure 1

Test data for Experiment 1. Total number of licks (top) and mean lick cluster size (center) are shown in 2-min time bins for each condition. The amount of sucrose solution consumed in each of the two conditions during the test trial is shown in the bottom panel. Error bars indicate ± standard error of the mean.

Figure 2

Test data for Experiment 2. Total number of licks (top) and mean lick cluster size (center) are shown in 2-min time bins for each flavor. The amount of sucrose solution consumed in each of the two flavors during the test trial is shown in the bottom panel. Error bars indicate ± standard error of the mean.

Figure 3

Test data for Experiment 3. Top panel: Total number of licks for Group Congruent (left side) and Group Incongruent (right side). Licking for Flavors X and Y are shown by black and white circles, respectively. Middle panel: Mean lick cluster size for Group Congruent (left side) and Group Incongruent (right side). Mean lick cluster size in Contexts A and B are shown by black and white triangles, respectively. The amount of sucrose solution consumed during AX and BY trials for Group Congruent, and AY and BX trials for Group Incongruent, is shown in the bottom panel. Error bars indicate ± standard error of the mean. Note that for the different measures there is change in the appropriate between group comparisons. For the analyses of total licks and consumption, the responses for AX and BX, and BY and AY, were compared between groups, but for lick cluster size AX and AY, and BY and BX, were compared between groups. Therefore, for total licks and consumption the factor of congruency refers to whether the flavor was presented in a congruent context, whereas for lick cluster size congruency refers to whether the context was paired with a congruent flavor.