Assessing appetitive choice discrimination learning in zebrafish

Within the last decade, the zebrafish (Danio rerio) has emerged as an important vertebrate model in developmental biology and medicine for problems typically associated with humans. However, where behavioral assays are needed, the utility of the zebrafish model has been limited by the narrow range of procedures so far developed to investigate zebrafish learning. The purpose of this study was to further develop and test procedures to study appetitive choice discrimination learning in zebrafish. Zebrafish were conditioned to swim into one of three chambers for food reinforcement. The correct (S+) chamber on a trial was signaled by the presence of a light stimulus in the chamber; the two negative (S-) chambers were dark. Each of the 15 fish tested learned the discrimination to a criterion of 80% correct in both of two consecutive sessions. Tests for stimulus control showed that discriminative behavior was indeed under the control of the S+ discriminandum. These results were discussed in relation to the recent report of zebrafish discrimination learning in a two-alternative task, and the importance of examining individual zebrafish learning curves.