A receptive field is a set of receptors that controls a neuron. Some neurons have a receptive field of only one receptor, some neurons have receptive fields of several hundreds of receptors.

The retina contains rods and cones, which are connected to the neurons in the laterale geniculate nucleus (LGN) through the optic nerve. Each eye counts approximately 120 000 000 rods and 6 000 000 cones. The optic nerve counts about 1 000 000 nerve fibers. So, there is an average convergence of 126 receptors to one nerve fiber, and thus neuron in the LGN.

Of course, this is an average and the size of the receptive field varies according to the position in the retina. In the peripheral part of the retina the receptive fields are quite large. The central part (the fovea) contains very small receptive fields; meaning that very few receptors are aggregated to one neuron in the LGN.

The shape of the receptive fields in the retina resembles a donut with a centre and a surround. When light falls on the center, the neuron in yhe LGN will be excited (fires more). When light falls on the surround, the neuron is inhibited (fires less). If light falls on both the center and the surround or outside the receptive field, nothing happens with the ganglion cell.

Stimulatiuon of receptive field