Holeboard discrimination learning in mice.

We have adapted to mice a holeboard-learning task, which allows simultaneous assessment of spatial working and reference-memory performance. The holeboard apparatus consists of an open-field chamber with a 16-hole floor insert. Across trials, animals have to learn that the same four holes of 16 are always baited. Here, we show that C57BL/6 mice readily acquire this task within 4 days when submitted to six trials per day or within 8 days when submitted to only four trials per day. We also show that C57BL/6, Swiss-Webster, CD-1 and DBA/2 mice acquire this task similarly, despite the fact that some differences could be observed in measures of exploratory activity during habituation and training. Moreover, the muscarinic antagonist scopolamine disrupts learning at doses of 0.1 and 1.0 mg/kg, although the highest dose appeared to have side-effects. Lastly, we found that amyloid precursor protein transgenic mice have a selective disruption in their working-memory performance only during reversal training (i.e. after a change in the configuration of the baited holes). Overall, our data indicate that this spatial learning task is well adapted to mice and will be useful to characterize spatial memory in various genetic or pharmacological mouse models.