Detailed behavioral analyses are a more suitable means to study sign-tracking responses. (A) Lever ppm on the CS+ (teal) and CS− (orange) levers throughout Pavlovian conditioning. Error ribbons display ± SEM. (B) Average food cup entries during CS+ presentations throughout Pavlovian conditioning. Error ribbons display ± SEM. (C) Histogram of calculated PCA indexes during session 12. Standard PCA index cutoffs for goal-tracking and sign-tracking are displayed by dotted lines at −0.5 and 0.5, respectively. (D) Illustrations of behaviors that were scored in session 12. Behaviors range from non-sign-tracking to increased sign-tracking intensity from left to right. (E) Heatmap depicting the detailed behavioral fingerprints of all animals in session 12. Darker blue regions indicate higher engagement with those behaviors, and lighter green to white represents the least engagement with those behaviors. Subjects are arranged in order of their calculated PCA index, from −1 to 1. PCA indexes of −0.5, 0, and 0.5 are marked by dotted black lines. (F) Scatterplot of behavioral intensity (behaviors in D scaled from −1 to 6, −1 representing food cup directed, and 6 representing lever bite) and CS+ lever ppm in session 12. (G) Scatterplot of the percentage of lever-directed behaviors scored (behaviors from lever orient through lever bite in D vs. food cup–directed and non-task-directed behaviors) and lever ppm in session 12. For all plots, asterisks (*) represent statistical significance (P < 0.05).
