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. 2020 Nov 26;14:604163. doi: 10.3389/fncel.2020.604163

Figure 2.

Figure 2

Reliability and kinetics of ChR2-mediated white-noise stimulation of starburst amacrine cells. (A) Construction of linear-nonlinear model from responses to optogenetic white-noise stimulation. (B) Top, optogenetic white-noise stimulus sequence. Maximum light intensity (Φmax), 3.2 × 1017 Q cm−2 s−1. Middle, ChR2 currents (IChR2) recorded in an ON SAC. Gray traces show responses to the repeated stimulus (trials 1 and 10). The average of all 10 responses (black) is overlaid with the output of the LN model (blue) generated from responses to unique stimuli. Bottom, same as middle for ChR2-modulated membrane potential (Vm) in a different ON SAC. (C) Linear filter (left) and static nonlinearity (right) obtained from recording IChR2 in ON SAC shown in (B). For the static nonlinearity, the horizontal line indicates the response corresponding to a linear prediction of 0 (in arbitrary units, a.u.). Solid curves are fits to measured nonlinearities (black points). (D) Same as (C) for Vm in ON SAC shown in (B). Inset shows linear filters for IChR2 (inverted) and Vm superimposed on an expanded timescale. Dashed lines indicate filter peak times. (E) Measurements of LN model components obtained from recordings of IChR2 (n = 7 cells) or Vm (n = 9 cells) in ON SACs. *p < 0.05; ***p < 0.001.