Retinal Ganglion Cell Receptive Fields

Receptive Field Type

Light Stimulus

Spot X position 0.00

Spot Z position 0.00

Spot radius 0.45

Surround strength 1.00×

Ganglion Cell Output

Center drive

0.00

Surround drive

0.00

Firing rate: 8.0 HzPeak: 8.0 Hz

How it works

A retinal ganglion cell pools input from many photoreceptors through bipolar and horizontal cells into a roughly circular center-surround receptive field (Kuffler, 1953). Its spatial sensitivity is well approximated by a difference of Gaussians (Rodieck, 1965):

K(d) = Ac · exp(−d²/2σc²) − As · exp(−d²/2σs²)

d  = distance from receptive-field center
σc = center radius,  σs = surround radius (σs > σc)
Ac, As = center / surround gains

An ON-center cell fires when light lands in the middle (Ac > 0) and is suppressed by light in the surrounding annulus (As < 0 relative sign); an OFF-center cell has the opposite arrangement. The predicted response is the overlap integral of this kernel with the stimulus's luminance pattern ΔL(x,z):

Response ∝ Σ K(dᵢ) · ΔL(xᵢ,zᵢ)   over every receptor i
Firing rate = max(0, baseline + gain · Response)

This is why a spot exactly filling the center excites an ON-center cell strongly, a spot covering both center and surround cancels out (uniform illumination barely changes firing — the classic "silent surround" result), and a bright edge crossing the boundary drives the cell hardest of all: center-surround fields are edge and contrast detectors, not brightness detectors.

Spot X / Z — move the light stimulus across the photoreceptor mosaic.
Spot radius — grow or shrink the illuminated area relative to the fixed center/surround rings drawn on the mosaic.
Surround strength — scales As; at 0 the cell behaves like a pure center detector, above 1 the antagonism dominates.
Auto-sweep — sweeps the spot through the field so you can watch the response rise, peak near the center, and fall as it crosses into the surround.

Excitatory drive Inhibitory drive Ganglion cell / spikes

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