A ganglion cell does not report how much light falls on it. It reports how the light in one small region compares with the light around it. Each demonstration below uses the same cell.
Demonstrations
Probing the visual field
Move the pointer over the field to place the probe, or let it sweep on its own.
What the cell reports
Each probed location is marked with the response it produced.
A spot centered on the receptive field
The spot grows outward from the center of the field.
Response against spot size
Firing relative to the maintained rate, drawn as the spot grows.
Four stimuli, two cell types
The same four patterns delivered to an ON-center and an OFF-center cell. Maintained rate shown dashed.
The stimulus
A row of identical cells tiles this image, each comparing its own center with its own surround.
Luminance in, response out
Above, the luminance across the image. Below, the population response.
A sinusoidal grating
The receptive field is drawn to scale against the bars.
Response against spatial frequency
Modulation depth of the cell's firing as the grating drifts past.
The stimulus
Look at one intersection while attending to the others.
What the center–surround model predicts
Response of a whole sheet of these cells, warm above baseline and cool below.
Arrow keys step through the demonstrations; space pauses.