Extended Data Fig. 5: EM reconstruction of LC4 neurons and estimated receptive fields.

a, Tracing of all 55 LC4 neurons on one side of the brain in FAFB EM volume. Two example neurons are colored in red and blue (same in “b”). LC4 neurons have dendrites in lobula layers 2 and 4. LC4 cell bodies are marked with grey circles. Two Tm5 neurons are chosen to determine the center and central meridian of the eye in “b”. b, Two-dimensional projection of the lobula layer. Traced LC4 dendrites (grey) are projected onto a surface fit through all dendrites (orange). Blue circles denote centers of mass of individual LC4 dendrites. Vertical line is the estimated central meridian that divides the eye between anterior and posterior halves. c, Pseudo-stimuli mimicking looming stimuli used in in vivo whole-cell recordings to simulate LC4DN responses based on LC4 connectivity. d, Confined DN RFs to the region of pseudo-stimuli in the eye coordinate imitating the looming stimuli. LC4 RFs based on connectivity to each DN are scaled by the proportion of overlapping with each stimulus region prior to sum up all the LC4 RFs. e, Estimated anatomical receptive fields (RFs) of the GF and DNp04 in the eye coordinates. f, Left: Estimated connectivity-based DN responses to pseudo-stimuli (solid) and measured responses to the corresponding looming stimuli (dashed) from in vivo whole-cell recordings. Right: Estimated responses in DNp04 and GF extrapolated using the connectivity model to looming pseudo-stimuli that cover the visual hemifield.