Tßh mutant flies walk slower and deviate less from stripes in Buridan's paradigm.

Abstract

A. Buridan’s paradigm. The platform in the middle of the arena is surrounded by water and illuminated with bright white light from behind. Two black opposite stripes are fixed to the arena wall. The centroid position of the fly was recorded by custom tracking software. All data are obtained from 5 min of uninterrupted walk. Data were analyzed using CeTrAn v.4. B. Flies. tshnM18 mutant and their genetic background control w+ (Schwaerzel et al., 2003) are crossed with CantonS wild type (P). One to two days old male flies were CO2-anesthetized (F1) and their wings were clipped at two thirds of their length. The flies recovered in the food vials overnight. Individuals were captured using a fly aspirator and transferred into the experimental setup on the center of the platform. The platform was cleaned with 70% ethanol after each experiment to minimize nonspecific effects. C. Mean of walking speed. A median of walking speed (traveled distance over time) was calculated for each fly. The mean of all flies is depicted in the graphs ± standard error of the mean. The tsh mutant males walk significantly slower than the wild type males (Welch Two-Sample t-Test, p = 2*10-8). D. Stripe deviation quantifies fixation behavior. It corresponds to the angle between the velocity vector and a vector pointing from the fly position towards the center of the stripe in front of the fly. Data are depicted as medians (bar), the 75%- and 25%-quartiles (box), and total data range (whiskers) excluding outliers outside the 1.5 times the interquartile range (points). Stripe deviation is significantly smaller in tsh mutant males compared to controls (Wilcoxon rank sum test, p = 4*10-10), meaning they fixated the stripes better than control flies. Numbers inside the graphs indicate the sample size. For methodological details see Colomb et al. (2012).