Figure 3. Multi-modal reverse-correlation experiments suggest attractive odor and light signals are combined linearly and early.

Or42a>CsChrimson larvae were presented with independently varying Brownian light intensities. Reverse-correlation analysis was carried out as in Figure 1. (A) TTA. Average change in red (fictive odor) and blue light intensities preceding turns. (B) Turn triggered ensemble. Top: 2D density histogram of calculated odor and light filter outputs at initiation of each turn. Bottom: 1D density histograms of filter outputs (x_O,x_L) and their linear combinations (u,v). D_KL(P(x|turn)||P(x)) is the Kullback-Leibler divergence from the turn-triggered distribution to the distribution of x at all times. Larger values indicate that x carries more information about the decision to turn. (C, D) Predicted turn triggered ensemble according to, (C) independent pathways model and (D) early linear combination model. Top panel: predicted density. Bottom panel: difference between predicted density and measured density. D_KL(data||model) is the Kullback-Leibler divergence of the model from the data; smaller values indicate a better match. ***** = P (Independent pathways model)/P (Early linear combination model) < 0.00001; Aikake Information Criterion Test. (E) Coordinate rotation described in text and used in bottom panel of B. Orthogonal coordinates (u,v) are rotated 33° relative to (x_O,x_L). Rotation is shown overlaid on turn-triggered probability density (B). See Table 1 for number of experiments, animals, and so on.

DOI: http://dx.doi.org/10.7554/eLife.06229.006

Figure 3—figure supplement 1. Graphical explanation of the independent pathways model.

DOI: http://dx.doi.org/10.7554/eLife.06229.007

Figure 3—figure supplement 2. Graphical explanation of the early linear combination model.

DOI: http://dx.doi.org/10.7554/eLife.06229.008

Figure 3—figure supplement 3. Visual and fictive olfactory stimuli do not cross-talk.

Larvae were presented with same red and blue Brownian light stimuli as in Figure 3. TTA of red and blue stimuli are shown on same axes as in Figure 3A. (A) Reproduced from Figure 3A: Larvae expressing CsChrimson in Or42a receptor neurons turn in response to increasing blue light and decreasing red light (fictive odor). (B) Genetically blinded larvae expressing CsChrimson in Or42a receptor neurons turn in response to decreasing red light (fictive odor) but are unresponsive to blue light. (C) Wild-type larvae not expressing CsChrimson turn in response to increasing blue light but are unresponsive to red light. See Table 1 for number of experiments, animals, and so on.

DOI: http://dx.doi.org/10.7554/eLife.06229.009