Fig. 5

Increased internal feeding drive causes reduced current avoidance. a Increasing the duration of food deprivation from 6 to 18 h has no effect on flies’ avoidance of 4.7- vs. 20-MΩ current at equal sucrose (ns p = 0.88, Mann-Whitney U test; n = 29, 30). b This was also true for proboscis and leg interaction preference (ns p = 0.50 and 0.42, n = 27, 28, 27, 28 arenas, 10 w* Berlin flies). c The combination of 100 mM sucrose with 4.7-MΩ current became attractive only after 18 h of food deprivation (***p = 0.0005; n = 27, 28 arenas). d This was also evident in the proboscis interaction preference (***p = 0.0005, n = 26, 28), while leg interaction preference remained unchanged (ns p = 0.38, n = 26, 30). e, f The same qualitative results are observed with a 15- or 120-min analysis of Canton-S flies: no effect of deprivation duration on proboscis interaction preference when sucrose concentrations are equal (e, p ≥ 0.63, n = 10 arenas each). Conversely, proboscis interaction preference increases when higher, 100 mM sucrose was paired with higher, 4.7-MΩ current and Canton-S flies were food deprived for 18 h (f, 15 min *p = 0.0476, 120 min *p = 0.0283, n = 19, 20, 19, 20 arenas)