Figure 2. Adaptation and saturation modulate ORN responses to broadly distributed naturalistic stimuli.

(a). Ethyl acetate whiffs of similar size (top) elicit ab3 LFP responses (middle) and ab3A firing rate responses (bottom) with different amplitudes. (b) 2-butanone whiffs of similar size (top) elicit ab2 LFP responses (middle) and ab2A firing rate responses (bottom) with different amplitudes. Bar graphs in (a) and (b) show that ordering in LFP and firing rate response does not correlate with whiff amplitude, but correlates with the intensity of the preceding whiff. Colors on bar graph correspond to colors in time series on the left. Deviations in LFP (c) and firing rate responses (d) from the median response vs. mean stimulus in the preceding 300 ms. Deviations in LFP (c, inset) and firing rate responses (d, inset) from the median response vs. whiff amplitude. (e) Deviations from the median of LFP responses (positive deviations: red, negative deviations: blue) as a function of the amplitude of the previous whiff and the time since previous whiff. Positive and negative deviations are significantly different ($p=0.01$, 2-dimensional K-S test). (f) Deviations from the median of firing rate responses (positive deviations: red, negative deviations: blue) as a function of the amplitude of the previous whiff and the time since previous whiff. Positive and negative deviations are significantly different, ($p=0.001$, 2-dimensional K-S test on firing rate deviations).

DOI: http://dx.doi.org/10.7554/eLife.27670.008

Figure 2—figure supplement 1. An NL model (static input nonlinearity followed by a linear filter) cannot reproduce context-dependence of LFP responses to similar-sized whiffs.

Input nonlinearity (a) and filter (b) fit to ab2 LFP responses to 2-butanone naturalistic stimulus. The input nonlinearity is a Hill function $S/(S+K_D^{})$ where S represents the input, and K_D the half maximum value). The nonparametric filter and parametric nonlinearity are fit simultaneously in an iterative manner (see Materials and methods). (c) Comparison of ab2 LFP responses and NL model predictions. (d) Linear filter extracted from the stimulus and the NL model prediction. Note that the filter is not the same as in (b); a filter extracted from an NL model is not guaranteed to be an unbiased estimate of the true one. (e) NL model responses vs. naturalistic stimulus projected through filter in (d), showing that the NL model shows deviations from linearity similar to what is observed in the data (cf. Figure 1c). (f–g) Context dependence of response in the ab2 data and model. (f) ab2 LFP responses to whiffs of similar size (same data as in Figure 1h). Note that the responses to isolated whiffs (purple, yellow) are larger than the responses to repeated whiffs (red, blue). (g) NL model responses to these whiffs. Note that the responses to isolated whiffs (purple, yellow) are smaller than the responses to repeated whiffs (red, blue), the opposite of the trend visible in the data.

DOI: http://dx.doi.org/10.7554/eLife.27670.009