Fig. 4: Target selection and facilitation in the inhibitory receptive field.

a Targets vertically ascend a display within CSTMD1’s excitatory or inhibitory receptive field, either individually or as a simultaneous pair. Targets are separated by 50° to avoid the 10° wide region of binocular overlap. Target trajectories can be Short, Long or used as Cues, illustrated with dashed lines. Example traces illustrate CSTMD1 responses to T_i and T_e. T_i generates inhibition, T_e generates excitation. b Boxplots with overlaid swarm plots illustrating the mean neuronal response over a 500 ms window (green shaded region in A). Total 480 trials across 13 dragonflies. In Paired Target conditions, neuronal responses are broadly distributed, with some trials exhibiting inhibition and others exhibiting excitation (p < 0.001). Compared to the Paired condition, a preceding T_i Cue shifts responses towards inhibition (p = 0.001) and a T_e Cue towards excitation (p = 0.008). c Responses in each of the 13 neurons to simultaneous paired target trials (black), T_i Cued trials (blue) and T_e Cued trials (red). The majority of neurons show inhibitory responses to Paired Target trials without cueing, however each neuron is able to respond to either the excitatory or inhibitory target with the appropriate Cue. d Stimulus pictograms illustrating three conditions; Probe Alone (Black line only), Probe preceded by a short Primer (Black and Cyan line), and Probe preceded by a long Primer (Black and Blue). Trajectories are illustrative as they overlie in experiments. e Averaged response across all trials (shaded region is standard error, 110 trials across 11 dragonflies) reveals the time course of inhibition. Presentation of a target within the inhibitory receptive field drives neural activity below spontaneous rates (−0.5 to 0 s). f Boxplots with overlaid swarm plots show that Probe response is reduced when paired with either a Short (400 ms) or Long (800 ms) primer. Spontaneous spike rate is also illustrated and was measured over an equivalent time period before the beginning of each trial. Statistical testing via Wilcoxon rank-sum test.