(a) Schematic of receptive field mapping stimuli: black and white
squares (8 deg x 8 deg) on a gray background. (b) Responses of an
ON-selective dLGN bouton to white squares (top) and an OFF-selective LP bouton
to black squares (bottom) at different positions. Left, two-photon image of dLGN
(top) and LP (bottom) projections in L1 of V1. Middle left, example fluorescence
traces of a single bouton (indicated by arrows; individual traces in gray,
averages in black) ordered according to stimulus position. Scale bars, 400%
ΔF/F, 2 s. Middle right, receptive fields of the boutons. Far right,
smoothed receptive fields. Line indicates receptive field outline (see Methods). (c,d) Distributions
of spatial receptive field size (c), and the ratio of major to
minor axis length of receptive fields (d) of dLGN and LP boutons
and V1 layer 2/3 cell bodies. Triangles indicate medians. ***, P <
10−10, Wilcoxon rank-sum test. dLGN: n = 2317 receptive
fields, 7 mice, LP: 1825 receptive fields, 13 mice, V1: 356 receptive fields, 4
mice.