Supplementary Figure 6: Dendritic spikes and action potentials are generated at high frequency in DSGCs.
From: Direction selectivity is computed by active dendritic integration in retinal ganglion cells
(a) Somato-dendritic recording of repetitive high-frequency initiation of dendritic spikes evoked by an incremental series of positive current steps delivered to the dendritic recording electrode (245 μm from the soma). (b) Pooled current-discharge relationship generated in response to dendritic (red symbols) or somatic current (black symbols) (n = 10 cells, dendritic recordings 247 ± 12 μm from the soma). Lines represent the average frequency. (c) Cumulative probability distribution of preferred-direction light stimuli-evoked instantaneous action potential firing frequency (data pooled from n = 18 cells). (d) Axonal action potentials inactivate dendritic spike generation only at short inter-spike intervals. Representative example of the impact of axonal action potential firing evoked by short (2 ms) somatic current steps (black traces) on the initiation of dendritic spikes evoked by dendritic current steps (700 pA; 198 μm from the soma). Note that at 2 ms interval dendritic spike generation is blocked. (e) Impact of axonal action potentials evoked at decreasing time-delays on the normalized (to dendritic spike evoked in isolation) peak amplitude of dendritic activity evoked by the indicated amplitude current steps.
