Figure 1

(A) Establishment of a Repetition Index (RI) uncovers quantifiable Tetrahydrocannabinol (THC)-induced behavioral stereotypy in adult zebrafish that differs from swimming patterns in the low concentration ethanol vehicle (B). (C) A schematic trajectory with inner and outer zones and formula to calculate the RI. (D) Repetitive patterns are extracted as cycle sets from the raw tracking and summed to give a RI value. (E) THC (1 μM) elicited a significantly greater RI than the control condition with EtOH (0.0015%) (****p < 0.0001), calculated as a mean ± SEM, (F) and caused a significant reduction in velocity during exposure (**p = 0.0077). Controls EtOH (n = 38), 40 nM THC (n = 6), 1 μM THC (n = 23) and 2 μM THC (n = 12). Time point t and the whole recording time interval T. Values without a letter in common are statistically different to the control condition (p < 0.05, Kruskal–Wallis and Dunn's multiple comparisons test).