We examined click here the turning response of flies using an array of motion stimuli rotating about the animal (Figure 5). L1 and L2 are required redundantly for responses

to rotating gratings (Clark et al., 2011, Rister et al., 2007 and Joesch et al., 2010). Flies lacking L1 function have specific deficits in turning responses to rotating light edges (a transition from darker to brighter), while flies lacking L2 function have strong deficits in turning to moving dark edges (a transition from brighter to darker) (Figures 5A, 5B, 5D, 5E, and S5, compare blue traces to both control traces; Clark et al., 2011). These results were substantiated by an opposing edge stimulus, in which light and dark edges move in

opposite directions, which evokes little turning response in wild-type flies, as the motion circuits tuned to light and dark edges cancel one another. L1-silenced flies turn in the direction of the dark edge motion (as the motion circuitry that normally responds to moving light edges is inactivated), whereas L2-silenced flies turn with the direction of light edge motion (as the motion circuitry that normally responds to moving dark edges is inactivated) (Figure S5; Clark et al., 2011). We next tested the behavioral contribution of L3 to motion detection. When we silenced L3 neurons using the L30595-Gal4 line, we detected no significant deficits when presented with rotating square wave gratings, single edges of either polarity, Epacadostat price or opposing edges ( Figures 5G–5I, blue traces; Figure S5). Likewise, flies in which the highly specific splitL4-Gal4 line was used to silence L4, also responded nearly normally to rotational stimuli ( Figures 5J–5L and S5). Similar results were obtained using the L40987-Gal4 driver ( Figure S5). Thus, neither L3 nor L4 are individually required to guide turning responses to rotational visual motion under the conditions tested. We below next examined whether these single cell type inactivation experiments might mask redundant functions

among input pathways. Interestingly, although L2 silencing alone reduced responses to rotating dark edges and caused turning in the direction of light edge motion in an opposing edges stimulus, some dark edge response remained (Figure 5E). Since L3’s physiological properties make it preferentially sensitive to contrast decrements, we tested whether L3 acts redundantly with L2. When both L2 and L3 were silenced, flies displayed turning responses to light edges (Figure 6A). However, they displayed no turning at all in response to a rotating dark edge stimulus and turned more strongly in the direction of light edge motion in an opposing edge stimulus than flies in which L2 was silenced alone (Figures 6B and S6). Thus, double silencing experiments uncovered a redundant role for L3 in the detection of moving dark edges.