Contrast sensitivity of neurons in mouse LGN.

<p>Examples of single cell response tuning to drifting gratings of varying contrasts are shown in A-D. Open circles indicate mean firing rates (average of 10 repetitions). Black curves show the best fits to a hyperbolic function. Red rhomboid indicates C₅₀ value. Note logarithmic scale of X-axis. Four types of responses were observed. A) A cell whose response amplitude increased sharply from very low contrast and began to saturate at relatively low contrast. B) A cell showing a sigmoid response curve: response amplitude began to increase rapidly after a short period of slow increase at low contrasts. C) A cell showing an almost linear increase in response amplitude with increasing contrast. D) A cell displaying a linear increase only at higher contrast. E) Distribution of contrast gain across the population. Mean (arrow) ± SEM = 0.98 ± 0.04 spikes/sec. F) Distribution of C₅₀ across mouse LGN cells. Mean (arrow) ± SEM = 0.50 ± 0.02.