Cigarette Smoke Extract Impairs Visual Behaviour. A. Schematic illustrating the timeline and experimental design of 48 hours cigarette smoke extract (CSE) treatment of zebrafish larvae and physiological analysis. B. Gross morphology of 5 dpf larvae treated with CSE showing no macroscopic abnormalities except for the incomplete inflation of swim bladder. C. The percentage of larvae with inflated swim bladders is only reduced at 15 or 20 µg/mL CSE, n=24 larvae per group, experiment repeated 3 times. D. Standard optokinetic response assay (0.02 cpd) at 5 dpf shows visual behaviour is significantly affected at 10, 15 and 20 µg/mL CSE; n=32 larvae per group, experiment repeated 4 times. Data were analysed by one-way ANOVA and Bonferroni´s multiple comparison test where **=p<0.01, ***=p<0.001 and ****=p<0.0001. Error bars indicate standard deviation (SD). E. Normal swimming response when caudal fin was touched at 5 dpf. N=16 larvae per group, experiment repeated 2 times. F. Heartbeat per minute average reveals no significant effects of CSE on cardiac rhythm at 5 dpf. N=8 larvae per group, experiment repeated 2 times.