Extended Data Fig. 3: Post-inhibitory rebound dynamics in the VNC (supplement to Fig. 3).
From: Flexible circuit mechanisms for context-dependent song sequencing
a, Anti-correlation between calcium responses of TN1 neuron pairs persists across trials. While Fig. 3c shows the correlation between trial-averaged calcium responses of TN1 neuron pairs in one fly, here we show the correlation between TN1 pairs for individual trials (7 trails, each trial consisting of four optogenetic stimulus presentations and a pause, as shown in Fig. 3b), only for pairs with trial-averaged anticorrelation coefficient below −0.8 (n = 17). b, Standard deviation (SD) across trials of the correlation coefficients shown in a). The majority of anti-correlated TN1 pairs are consistent across trials. c, Song of a mutant male systematically lacking Ih, courting a wild-type female. d, Overall sine probability (fraction of time spent singing sine song in a 30-minute recording) for two different strains of Ih mutants (mutant A, \({I}_{h}^{03055}\), and mutant B, \({I}_{h}^{01485}\); see Supplementary Table 2) and wild-type males. e, Proportion of simple pulse bouts in song of Ih mutants and wild-type males, produced far from (>4mm) a wild-type female. f, Proportion of simple pulse bouts in song of Ih mutants and wild-type males, produced near (<4mm) a wild-type female. g, Song of males with TN1-specific downregulation of Ih or Rdl (GABA-A receptors). h, Mean number of pulse-sine alternations in song of males with TN1-specific downregulation of Ih or Rdl (GABA-A receptors), and genetic controls (see Supplementary Table 2), produced near (<4mm) a wild-type female. i, Proportion of complex bouts with leading pulse mode, in song of males with TN1-specific downregulation of Ih or Rdl (GABA-A receptors), and genetic controls (see Supplementary Table 2), produced near (<4mm) a wild-type female. h-i, n = 17 for TN1 > Ih, n = 20 for TN1 > Rdl, n = 15 for genetic controls (all biological replicates). The effect of Ih reduction was modest, possibly because neurons other than TN1 contribute to sine song production, because rebound excitability in TN1 neurons arises from a degenerate set of ion channels that are robust to small perturbations (via knockdown) of Ih67, or because a reduction of Ih channels maintains some rebound excitability through increased channel conductance at stronger hyperpolarization68. d-f, n = 7 for mutant A, \({I}_{h}^{03055}\), n = 9 for mutant B, \({I}_{h}^{01485}\), and n = 20 for wild-type males (biological replicates). d-f,h,i Wilcoxon rank-sum test for equal medians; *P < 0.05, **P < 0.01, ***P < 0.001; NS, not significant.
