2020 Volume 38 Issue 1 Pages 21-33
We investigated the effect of a blockade in the D1 dopamine receptor (D1DR) of the bilateral medial prefrontal cortex on interval timing in rats. A peak-interval (PI) procedure consisting of a standard operant task using food pellets was conducted to evaluate interval timing precision and accuracy. Compared to the vehicle (0.0 µg), the D1DR antagonist SCH23390 (0.5 µg) flattened the response rate curve and decreased the discrimination index (DI), an index of temporal precision, without altering the within-trial response rate. Neither the response rate curve nor DI changed after administering 1.5 µg SCH23390, although the within-trial response rate decreased. We also observed a similar overall decrease in a different timing-free operant task. In contrast, temporal accuracy indices remained constant across all doses. These results suggest that the D1DR blockade in the medial prefrontal cortex of rats decreases the precision but not the accuracy of interval timing.
