Fig. 3.

Trajectory patterns change with learning. A: three example trajectories from the Early, Late and Probe trials. No food was placed during Probe trials. Trajectories are plotted once the fish has left the edge of the tank. Note that, even during Late trials, the fish will take a curved route to the food, and that its final angle of approach to the food is very variable. The trajectories during Probe trials are clearly centered on, or near, the food location of the previous trial. Blue box indicates one of the landmarks. Throughout this figure, black arrows indicate the food location, and the red arrow indicates the missing food location. B: visit density maps quantify the number of times animals visit each grid location and are plotted here for the Early, Late, and Probe trials. The pseudo-colors indicate the visit count density per grid location (2.7 × 2.7 cm² square) and was normalized by the maximum count value across all grid locations after pooling trajectories from all animals. C: the search area fraction is defined as the fraction of area above threshold in the visit density map (right). The search area fraction was computed for each visit density map (mean ± SE) and compared between Early, Late and Probe trials. D: pseudo-colors represent average time spent in each grid location per visit for the Early, Late and Probe trials. Black arrows indicate the food location, and a red arrow indicates a missing food location. E: search time fraction is defined as fraction of time spent in a region of interest (unmasked image portion). Search time fractions were plotted near all landmarks (within 3 cm from the object edges) or near food (within 15 cm from the food center). Box plot represents the median, interquartile range and extrema (red crosses indicate outliers). *P < 0.05. **P < 0.01. ***P < 0.001.