LGALS4 and Alzheimer disease: Phototaxis activity (expressed as light preference index) was also decreased in 10-day-old AD model flies [GMR-GAL4-UAS-TauWT/+, GMR-GAL4-UAS-Aβ42(Human)/+ and GMR-GAL4/+;UAS-ApplRNAi/+] to 7.3, 10.3 and 10.0, respectively, as compared to GMR-GAL4/+ flies which had a light preference index of 17.8 (Fig. 1F).