Figure 2: The impact of ON-SACs aligns with the directional tuning of postsynaptic ON-DSGCs. | Nature Communications

Figure 2: The impact of ON-SACs aligns with the directional tuning of postsynaptic ON-DSGCs.

From: Dendro-dendritic cholinergic excitation controls dendritic spike initiation in retinal ganglion cells

Figure 2

(a) Reconstruction of a connected pair of ON-SAC (green) and ON-DSGCs (black), showing the sites (red symbols), and vectorial angle (red arrow, relative to SAC somata) of close dendro-dendritic appositions. Morphologies have been aligned to the preferred direction vector of ON-DSGC light responses (b inset). In all panels the preferred side of the ON-DSGC, the dendritic field first activated by light stimuli moving in the preferred direction, lies above the horizontal dashed line. Note that the SAC somata and all dendro-dendritic close appositions are positioned on the preferred side of the postsynaptic ON-DSGC. (b) Paired recordings from the illustrated cells (a) revealed that activation of the SAC-evoked excitatory PSPs in the ON-DSGC (grey traces, red trace is a digital average). The somatic current-evoked presynaptic SAC voltage responses are shown below (green trace). (c) Reconstruction of an ON-SAC located in the null side of an ON-DSGC. The morphologies have been aligned to the ON-DSGC light response vector (d inset). (d) Paired recordings from the illustrated cells (c) revealed SAC-mediated inhibitory PSPs (grey traces, blue trace is a digital average). (e) Summary of the impact of SACs located on the preferred and null sides of postsynaptic ON-DSGCs. The morphologies of postsynaptic ON-DSGCs are shown as overlain and spatially filtered (50 μm, black) reconstructions registered to the preferred direction of light responses, shown schematically by the yellow light bars. Nested within this field are perimeter representations of SACs (green). Arrows indicate the vector angle of SAC-DSGC close dendro-dendritic appositions coloured according to their postsynaptic impact (red excitatory, blue inhibitory PSPs). Vector length represents 1 contact per μm. All light stimuli, the direction of which are schematically illustrated, were applied under photopic conditions. Stimulus intensity was twice that of background illumination.

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