Object location and object recognition were performed as previously described28,51. Prior to training, mice are handled 1-2 min for 5 days and then habituated to the experimental apparatus for 5 min a day for 4-6 days in the absence of objects. During the training period, mice were placed into the experimental apparatus with two identical objects (100 ml beakers or light bulbs or vases) and allowed to explore for 10 min51. During the retention test, (24 hrs for long-term memory or 90 minutes for short-term memory), mice were allowed to explore the experimental apparatus for 5 min. Exploration was scored when a mouse's head was oriented towards the object within a distance of 1 cm or when the nose was touching the object. The relative exploration time (t) is recorded and expressed as a discrimination index (D.I. = (tnovel − tfamiliar) / (tnovel + tfamiliar) × 100%). Mean exploration times were then calculated and the discrimination indexes between treatment groups compared. Animals that explored less then 3 sec total for both objects during either training or testing were removed from further analysis. Animals that demonstrated an object preference during training (D.I. > +/− 20) were also removed.
