Effects of scopolamine and D-cycloserine on non-spatial reference memory in rats

The aim of the present work was to use a three-choice simultaneous brightness discrimination test to examine the retention of non-spatial reference memory in rats treated with scopolamine (0.5 mg/kg) alone and in combination with various concentrations of D-cycloserine (DCS) (5, 15 and 50 mg/kg). Scopolamine given 1 h before testing for retention was found to increase both the number of errors and the number of trials necessary to reach criterion. The three doses of DCS reduced this increase significantly and resulted in a U-shaped dose-response curve, where 15 mg/kg had a stronger compensatory effect than both 5 and 50 mg/kg. Control experiments were performed to confirm that the observed response was not due to non-mnemonic factors. Our results indicate that scopolamine and DCS affect non-spatial reference memory in a similar manner as shown for spatial reference memory.