Figure 6.

PG construction for back-to-front response to the leading edges of figures and edge-type stimuli across all cell classes. A, T5 neurons are local motion detectors. Time series shows temporally aligned mean responses from Figure 4E for the eight front-to-back stimulus conditions. The highlighted window corresponds to the analysis interval, which in turn corresponds to the highlighted time point on the covariance matrix. The red trajectories correspond to the five stimuli the linked elements at this time point. For the covariance matrix at the specified time point, a p value of 0.01 is white. Brackets correspond to rows of the matrix that contain non-zero entries and correspond to stimuli in the perceptual graph. Graph shows the PG for the LPN responses of the fly. Edges are drawn only for covariance values that are significant at a threshold set by p < 0.01. Edge color corresponds to the covariance values from the covariance matrix. Covariance time series shows the number of discrete clusters in the PG as a function of the starting position of the time window. The two peaks evident in each heatmap correspond to clustering events elicited by passage of the leading and trailing edges of a figure through the receptive field of each ROI. B, LC12 neurons are ground-suppressed edge detectors. Analogous subfigure to A. C, LC9 neurons are figure–ground discriminators. Analogous subfigure to A. D, LC10a neurons are figure–ground discriminators. Analogous subfigure to A. E, Representative example of the covariance matrices at the specified time point across individual flies for the LC10a neuron subclass. The topology of the mean PG is largely preserved, even at the level of individual flies.