Obtaining PSTHτ transiency values in this study.

<p><b>(A).</b> Extracellular spike recordings (middle trace) were detected upon photopic light stimuli (bottom trace). Spikes were sorted offline by using the appropriate threshold line (dashed line) to determine spike timestamps (top trace). <b>(B).</b> To quantify transiency, peristimulus time histograms were created upon light response timestamps using the light onset as reference. PSTHτ values were obtained by determining the peak time (t_peak) and the peak amplitude (A1) and then A1*1/e was calculated and that gave the time constant itself (τ).</p

PSTHτ values depict the stimulus dependency of RGC responses.

<p><b>(A).</b> Selected RGC (n = 6) PSTHτ values obtained upon full-field light evoked responses were stable (cells 1, 2, 5 and 6) while those of others (cells 3 and 4) displayed some intensity dependent change. <b>(B).</b> PSTHτ values of selected RGCs (n = 4) were obtained by a series of light spots with varying diameters (10, 20, 40, 60, 80, 140, 180, 270 and 360 μm). RGC PSTHτ values change according to the size of the presented stimulus. <b>(C).</b> Histogram is showing PSTHτ values for RGC (n = 6) responses. PSTHτ values were calculated for PSTHs obtained with different bin sizes (10, 20 and 30 ms) for each cell.</p

Trial-to-trial reliability of the PSTHτ approach.

<p><b>(A).</b> Representative light responses of a mouse ON center cell evoked by six consecutive full-field, photopic light stimuli. <b>(B).</b> Although the same stimulus was presented to compare the reliability of the four different methods, the standard deviations (SD) for the calculated transiency values were very different when they were compared for twelve different cells. <b>(C).</b> Histogram showing values obtained by averaging the SD values for the four compared methods for RGCs from Fig 3B.</p

Comparison of PTSHτ and slow potential τ values.

<p><b>(A).</b> Intracellular recording from an ON center RGC in the mouse retina that displays both slow potentials and spikes (upper trace). Spikes (second trace) and slow potentials (lower two traces) were obtained from the same recording by applying either a high-pass (>100 Hz) or a low-pass filter (<50 and 100 Hz for the third and fourth traces), respectively. Spike trains and slow potentials were then utilized to calculate both PTSHτ and τ values for the same light responses. <b>(B).</b> Bar-graph shows PTSHτ and τ triplets for randomly selected RGCs. In each column PTSHτ and τ values appeared comparable for the tested cells.</p

PSTHτ values depict the stimulus dependency of RGC responses.

<p><b>(A).</b> Selected RGC (n = 6) PSTHτ values obtained upon full-field light evoked responses were stable (cells 1, 2, 5 and 6) while those of others (cells 3 and 4) displayed some intensity dependent change. <b>(B).</b> PSTHτ values of selected RGCs (n = 4) were obtained by a series of light spots with varying diameters (10, 20, 40, 60, 80, 140, 180, 270 and 360 μm). RGC PSTHτ values change according to the size of the presented stimulus. <b>(C).</b> Histogram is showing PSTHτ values for RGC (n = 6) responses. PSTHτ values were calculated for PSTHs obtained with different bin sizes (10, 20 and 30 ms) for each cell.</p

Comparison of alternative methods to characterize response transiency regarding various criteria.

<p>Symbols +, ++ and +++ represent weak, good and excellent performance.</p

Previously used methods to determine transiency of RGC light responses.

<p><b>(A).</b> modified Sustained-transience index (mSTI) is calculated by dividing the spikes (time stamps of spikes are shown on the top trace) that occur during the second 200 ms after the stimulus onset (dark grey shading) by the spikes corresponding to the first 200 ms of the response (light grey shading). <b>(B).</b> Panel displays the PSTH generated upon light responses of a representative ON-OFF RGC. In case of the ON response of this neuron no spikes are detected during the second 200 ms, thus calculated mSTI values (mSTI = 0) do not reflect response transiency properly. <b>(C).</b> The Tr₂₀₀ measurement is performed by determining the exact time of the response peak (t_peak) and then obtaining the amplitude value of the PSTH curve (A2) corresponding to the time that occurs 200 ms following the peak response (t₂₀₀). <b>(D).</b> The Tr₂₀₀ approach fails to provide a precise transiency value when the response PSTH displays fluctuations, local minimums and maximums. <b>(E).</b> The area measurement approach is performed by a normalization of the PSTH curve and then determining the area outlined by the PSTH curve and the on- (t₀) and offsets (t₅₀₀) of the light stimulus. <b>(F).</b> Contrary to the similar shape of ON- and OFF components of this ON-OFF RGC light response, the area measurement approach provides very different transiency values due to a more robust shoulder for the ON response component. <b>(G).</b> Two OFF RGC PSTHs resulted in similar area summation values, however they displayed very different response characteristics. The onset of the photopic light stimulus is shown by the white bar, whereas the black bar shows light offset in the bottom trace for all panels.</p