Fig. 7. Antennal immobilization greatly reduces the orientation response. (A) Orientation traces from flies that had their antennae glued, either unilaterally or bilaterally, indicate a decrement in orientation ability. (B) At 0.2 m s^–1, orientation was not significantly different from baseline in bilaterally glued flies (t=0.24, d.f.=31, P=0.49), or in flies with the right (t=–2.77, d.f.=25, P=0.055) or left (t=–0.35, d.f.=28, P=0.37) antennae unilaterally glued. Control flies, however, did orient significantly better than baseline at the lower velocity (t=–4.84, d.f.=26, P<0.001). At 1.0 m s^–1, all groups oriented significantly better than baseline (non-glued: t=–5.26, d.f.=26, P<0.001; right antenna glued: t=–4.04, d.f.=25, P<0.001; left antenna glued: t=–3.61, d.f.=28, P<0.001; both antennae glued: t=–3.65, d.f.=31, P<0.001). (C) The percentage of the response attributable to a single JO was quantified by subtracting the mean response index for bilaterally glued flies from the corresponding mean values for flies with one antenna glued and dividing by the unilaterally glued response (filled circles). The effect of the second JO was similarly calculated from the responses of non-glued flies and the mean unilaterally glued responses (open circles).