Background: Alcoholics and heavy drinkers score higher on measures of impulsivity than nonalcoholics and light drinkers. This may be due to factors that predate drug exposure (e.g. genetics) or to neuroadaptations associated with exposure to alcohol. The aim of this study was to examine the role of genetics by comparing impulsivity in short-term selected lines of mice bred to voluntarily drink either high (STDRHI2) or low (STDRLO2) amounts of 10% ethanol.
Methods: Independent sets of mice completed 2 experiments designed to measure impulsivity. Using the adjusting amount procedure, we examined preference for smaller, sooner rewards over larger but delayed rewards (delay discounting). This task determines the amount of immediate sucrose equivalent to the discounted value of a 20 μl sucrose reward given following a specific delay (0, 2, 4, 8, or 12 seconds). Using a Go/No-go task, we examined the ability of mice to inhibit nose-poking in response to specific cues. These tasks are commonly used to assess different aspects of impulsive behavior, and provide measures that are not highly correlated.
Results: No significant differences were found between STDRHI2 and STDRLO2 mice in delay discounting. In the Go/No-go task, STDRHI2 mice made more responses during the pre-cue period without committing more false alarms, compared with STDRLO2 mice.
Conclusions: The results suggest that short-term selective breeding for high relative alcohol consumption may also select for animals that have impaired response inhibition.