Figure 1. Modes of multisensory integration during navigation.

(A) Suppression occurs when two cues drive mutually exclusive behavioral states. A hungry fly will track odor in the absence of other cues. Activation of taste receptors reduces or halts locomotion, although odor is still present. Adapted from Sayin et al., 2019.

(B) Gating occurs when one cue modifies a fly’s response to a second cue. Flies orient downwind in the absence of odor. Addition of odor (orange) induces upwind orientation. Adapted from Alvarez-Salvado et al., 2018.

(C) Summation occurs when two cues influence the same navigation parameter. In this case, a strongly attractive visual stimulus (purple) and a weakly aversive wind stimulus (green) each bias turn rate and direction. The strong drive to turn toward the visual cue is summed with the weak drive to turn away from the wind cue. The result (gray) is a turn of intermediate angular velocity toward the stronger (visual) cue. Adapted from Currier & Nagel, 2018.

(D) Association occurs when a cue that promotes innate attraction or aversion is paired with an innocuous cue from another modality. Here, noxious heat (red) is paired with orientation toward a visual pattern. The visual stimulus becomes associated with heat avoidance, causing the fly to turn away from the visual cue presented alone. Adapted from Liu et al., 2006.