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. 2015 Jun 24;35(25):9281–9286. doi: 10.1523/JNEUROSCI.0670-15.2015

Figure 4.

Figure 4.

Synapses from null-side SACs are located closer to the DSGC soma than synapses from preferred-side SACs at P13–P14. A, Model in which SAC-DSGC synapses are located where the DSGC's dendrites overlap with the portion of the SAC dendritic arbor (dashed circles) oriented in the DSGC's null direction (red shading, temporal retinal direction for Drd4-GFP+ cells; Briggman et al., 2011). The null-oriented portion of the null-side SAC's dendritic arbor overlaps extensively with the DSGC's dendrites at both proximal and distal locations. In contrast, the null-oriented portion of the preferred-side SAC's dendritic arbor only overlaps with DSGC dendrites at very distal locations. Thus, upon depolarization of the preferred-side SAC signals from synaptic events will experience greater dendritic filtering when recording at the DSGC soma. All diagrams are to scale based on average dendritic arbor size at P14 (Wei et al., 2011) but note that DRD4-GFP+ cells often have asymmetric dendritic fields (Rivlin-Etzion et al., 2011). Null- and preferred-side SAC somata are located 89 and 70 μm away from the DSGC soma respectively, the average intersoma distance for the two groups at P13–P14. B, Heat map of average a-mIPSC rise times. Small circles are SAC soma locations relative to the DSGC soma. Null-side SACs close to the DSGC have the fastest rise times, whereas preferred-side SACs the same distance away have slower rise times. C, Average cumulative probability distributions of 10–90% a-mIPSC rise times for null-side and preferred-side SAC-DSGC pairs with intersoma distances <100 μm (6 null-side pairs, 8 preferred-side pairs). Dashed lines are cumulative probability distributions for individual pairs. D, Average 10–90% a-mIPSC rise times for SAC-DSGC pairs in C (Welch's t test, p = 0.049, df = 11.98). E, Average 10–90% IPSC rise times for SAC-DSGC pairs for the initial IPSCs in the paired-pulse protocol (Fig. 2A; Welch's t test, p = 0.025, df = 19.5). Rise times measured from the same DSGC are connected via dashed lines of the same color for D and E.