What does the ERG record in the retina?

The electroretinogram (ERG) is a test that measures the electrical responses of cells in the retina when exposed to light stimuli. Primarily, the ERG records the graded potentials generated by photoreceptors (rods and cones) and their subsequent signaling pathways, which include bipolar and amacrine cells. This means that the responses recorded are proportional to the intensity of the light stimulus and reflect the underlying processes of phototransduction and synaptic transmission occurring within the retina.

The graded potentials captured by the ERG indicate how effectively the retinal cells respond to visual stimuli, which is crucial for assessing retinal function. This response is distinct from action potentials, which are all-or-nothing signals typically found in ganglion cells and other neural tissues, as the ERG focuses specifically on the graded potentials that suggest how the retina processes visual information. Therefore, in the context of the provided options, the correct answer accurately captures the essence of what the ERG measures.