Figure 3

Isochronic early AP-born neurons have diverse connectivities and molecular identities. (a) Schematic representation of the retrograde labeling strategy for E13.5-born neurons. Large arrowheads refer to sites of injection in (b–d). (b-d) Radial position of retrogradely-labeled E13.5-born neurons (red circles). Gray circles indicate E13.5 isochronic neurons, red circles are retrogradely-labeled cells in this population. Boxplots indicate mean and standard deviation of radial position. (e) Left: Experimental approach used for single-cell Patchseq. Bottom left: DIC image of a FT⁺ neuron right before nuclear suction (pipette visible on the right); bottom right: same neuron following biocytin filling. Right: Isochronic neurons express appropriate lamina-enriched markers. Top: Insets plotting recorded laminar position (y axis) and expression (normalized RPM values, white to red color gradient) of the respective gene. Number of cells = 49. Bottom: Corresponding in situ hybridization image in S1 from Allen Brain Atlas, P4 database. (f) Expression of the layer-specific proteins TBR1, CTIP2, CUX1, and SATB2 by E13.5-born (top) and E15.5-born (bottom) neurons. The position of E13.5-born neurons matches the laminar locations of the expressed marker (n = 3 pups/condition). Neurons expressing a given marker are shown in red (negative neurons are in grey). Box plots indicate mean and Standard Deviation of the radial position of positive neurons. Scale bars: 200 µm (b–d, low magnification), 5 µm (b–d, high magnification), 4 µm (f), 10 µm (e). DIC Differential Interference Contrast; E Embryonic day; FT FlashTag, L Layer; P Postnatal day; p1, p2, p3 Pup number, R.P.M. Reads per million.