Fig. 5: Neural circuit model of context-dependent song patterning.
From: Flexible circuit mechanisms for context-dependent song sequencing
a, Circuit model for male song patterning far from and near a female. mfDist (top), the only input to the model, enters the circuit via the pC2 node (see Methods), which drives the pulse pathway. Strong input (near the female) additionally disinhibits the VNC rebound circuit, enabling complex song production (alternating activity of the pulse and sine nodes). Grey indicates nodes becoming inactive at far or near conditions. Here, bout termination mainly relies on increases in mfDist (Extended Data Fig. 6a,b), consistent with ref. 3. b, Spiking neuronal network of four nodes (pC2, inh, p and s) representing the key computational features of the circuit in a, disinhibition, rebound excitability and mutual inhibition, fit to wild-type courtship data (see Methods). Model simulations with brief and weak (top) or long and strong (bottom) input to pC2 (corresponding to mfDist = 4.2 and 1.5 mm) result in either simple (‘p’) or complex (‘psp...’) song outputs. c, Song statistics for genetic algorithm fits of the model in b to song data at far (top) or near (bottom) distance (see Methods; experimental distributions shown in Extended Data Fig. 7k). The model reproduces bout statistics of courting wild-type flies (see Fig. 1d). d,e, Average mfDist (d) or population-averaged probability (mean ± mean absolute deviation from the mean) at a given mfDist (e) of simulated simple pulse, simple sine or complex bouts (models as in c) matches observations in courting wild-type flies (see Fig. 1c,f). Vertical grey line in e separates near and far contexts. f, Fit error (genetic algorithm objective function) for the full model versus models with individual computational features knocked out (see Methods), or disinhibition replaced with an excitatory motif (‘exc modulation’; see Methods; Extended Data Fig. 7a–c). For c–f, n = 24 (c–e) and n = 93 (f) genetic algorithm model fits to song (400 and 200 s each for c–f) randomly chosen from n = 20 wild-type recordings (biological replicates). For d,e, Wilcoxon rank-sum test for equal medians. *P < 0.05, **P < 0.01 and ***P < 0.001. For c,d,f, central mark indicates the median; the bottom and top edges of the box indicate the 25th and 75th percentiles, respectively. Whiskers extend to 1.5 times the interquartile range away from the box edges.
