Spike-Triggered Covariance Analysis Reveals Phenomenological Diversity of Contrast Adaptation in the Retina
Fig 1
Spike-triggered analysis of contrast adaptation.
Analyses for three sample cells, representative for Type I (top), Type II (middle), and Type III (bottom), under high contrast (purple) and low contrast (orange). (A) Firing rate histograms, averaged over all trials of high contrast (0–20 s) and low contrast (20–120 s). Note that the firing rates were obtained as trial averages with a different white-noise sequence in each trial. (B) Spike-triggered averages (STAs) for each contrast. (C) Corresponding nonlinearities for each contrast. Note that the slightly non-monotonic shape of the nonlinearity for the second sample cell reflects On-Off response characteristics of this cell [23]. (D) Eigenvalue spectrum obtained by STC analysis. The eigenvalues corresponding to the most and second-most informative features are marked by green and light blue circles, respectively. (E) Scatter plot of spike-triggered stimuli, projected onto the most informative stimulus feature k1 and the second-most informative feature k2. For clarity, only 10% of all analyzed spikes are shown in this plot.