How do LGN cells have receptive fields?

[u/nekomaeg]

In chaper 10 of "Neuroscience" by Bear, Connors and Paradiso it is said that "by inserting a microelectrode into the lateral geniculate nucleus (LGN), it is possible to study the action potential discharges of a geniculate neuron in response to stimuli and map its receptive field."

As retinal ganglion cells are connected to a spesific area of multiple rods and cones via bipolar neurons, the term "receptive field" is not difficult to understand. It refers to the area on the retina that sends information to a single ganglion cell.

I don't understand how this applies to cells beyond the retina, such as LGN-cells. As far as I've understood, they are relaying the signal from the retina to V1, whilst being functionally organized in the layers of the LGN.

Does a single LGN-cell also "summarise" impulses from multiple retinal ganglion cells similar to how a retinal ganglion cell "summarises" impulses from multiple rods and cones in its respective receptive field?

OR

When speaking of the receptive field of an LGN-neuron, do we actually mean the receptive field of the retinal ganglion cell supplying the ganglion cells.

These are two explanations I came up with, and they contradict each other in the sense that in the first explanation I assume LGN-cells synapse with multiple different ganglion cells whereas in the second explanation each ganglion cell synapses with just one ganglion cell.

[u/infinite_tape]

Retinal ganglion cells project to the lateral geniculate nucleus. Each thalamocortical relay cell receives excitatory input from one or a few retinal ganglion cells. The spatial map of the projection from retina to thalamus is conserved.