A. Live two-photon images of (Left) a P10 On-Off DSGC, (Middle) a P9 On DSGC, and (Left) a P11 Off DSGC, all prior to eye-opening. The On-Off and On DSGCs were filled with Alexa 594 prior to imaging. B. (Top) Labeled somas in a P5 Spig1 retina (which express GFP in On-DSGCs) bolus loaded with the calcium indicator OGB-1 AM, imaged with a GFP cube. (Bottom) The same region imaged with a CFP cube, which preferentially activates GFP over OGB-1 AM. A GFP+ cell is shown in the cell-attached recording configuration. The membrane of the GFP+ cell is visible within the electrode. C. (Top) The ΔF/F trace reveals periodic retinal waves passing over a 200 × 200μm region centered on the GFP+ cell shown in A. Dashed line indicates the threshold used for isolating waves. (Middle) Spike bursts elicited from the GFP+ cell during waves. Inset shows the spikes for a single wave.

A. Top Left frame is a fluorescence image of a P5 Spig1 retina (which express GFP in On-DSGCs), loaded with the calcium indicator OGB-1 AM. Subsequent frames show the sequential binarized image frames for a single retinal wave used to measure wave direction and speed. Last frame is an overlay of binarized wavefronts with increasing time depicted by lighter regions. Arrow indicates the wave propagation direction obtained from the normalized vector sum of all the steps of the wavefront (black line). B. (Left) Histogram of wave directions for all P3–P5 recordings revealed a small but significant bias for waves propagating in the nasal direction (p < 0.05, Rayleigh test, N = 202 waves from 13 cells in 7 retinas). (Right) The nasal bias was more pronounced in P9–P10 retinas (p < 0.001, Rayleigh test; N = 468 waves from 27 cells in 19 retinas. Bin size = 45 degrees). C. (Left) A histogram of wave speeds for all P3–5 recordings. Top bar shows the approximate speed tuning for adult mouse On-Off DSGCs (adapted from Weng et al., 2005). Directional responses become stronger as wave speed increases beyond a few deg/s as indicated by the lightening of the bar. Bottom axis shows the same speeds in μm/s. Median wave speed = 104 μm/s = 3.5 deg/s. N = 279 waves from 15 cells in 9 retinas. Bin size = 15 μm. (Right) All P9–10 wave speeds. Median wave speed = 100 μm/s = 3.3 deg/s. N = 572 waves from 28 cells in 20 retinas. Bin size = 15 μm.

DSGC spike counts as a function of wave direction at P3–5 (A) and P9–10 (B). Waves were grouped into 4 bins centered along the cardinal axes according to their propagation directions. Gray circles show the spike count evoked by a single wave (X axis jittered for clarity). Black diamonds indicate the median ± the bootstrapped 95% confidence intervals (see Methods). Insets show the preferred directions of the labeled sub-types for each mouse line (black arrows), as well as the preferred directions of the non-labeled cells belonging to the same types (gray arrows). P3–5 On-Off: 30 nasal (N) waves, 32 dorsal (D), 16 temporal (T), 16 ventral (V); recorded from 8 cells in 5 retinas. P3–5 On: 36 N, 15 D, 29 T, 21 V; recorded from 6 cells in 3 retinas. P9–10 On-Off: 128 N, 24 D, 7 T, 24 V; recorded from 11 cells in 6 retinas. P9–10 On: 66 N, 25 D, 18 T, 50 V; recorded from 8 cells in 6 retinas. P9–10 Off: 52 N, 37 D, 20 T, 17 V; recorded from 8 cells in 7 retinas.