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Fig. 4 | BMC Biology

Fig. 4

From: A simple threat-detection strategy in mice

Fig. 4

Responses induced by simulative natural visual stimuli. a Simulation of an approaching natural object using an expanding shadow. The time history of the shadow’s size (θ) is described by the function f (θ,t). b The size-expanding speed curves of approaching objects with different radius to velocity ratios (r/v) and a free-falling apple. The alert range (expanding speed was 57320°/s and angular size was 10–40°) is marked by a black dotted box. c Time of each stimulus in the alert range. dh Stimuli simulating several natural objects approaching at a constant speed. The first period of each visual stimulus is shown. i Stimulus simulating an apple free-falling from the tree. j Time to reach the refuge for each visual stimulus. k Maximum speed for each visual stimulus. l Distance ratio for each visual stimulus. m Freezing time in the open field for each visual stimulus. n Rearing count for each visual stimulus. o The latency to make the first response for each visual stimulus. Each dot in jo represents the result of one looming test trial from one animal. The number of mice and trials for each group is summarized in Table 4. Rank sum tests were calculated for comparisons between the experiment and control groups, and the statistical significance between each pair of groups was corrected using the Bonferroni method. Asterisks indicate the level of statistical significance of the fear indices compare against the negative control group (θ = 0°), *p < 0.05, **p < 0.01, ***p < 0.001, #p = 0.064

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