The human cone electroretinogram (ERG) to a full field flash has been examined on a rod saturating background (17,000 photopic trolands). With strong stimuli, a negative wavelet appears in the falling phase of the a-wave. This response has a latency of 10–12 milliseconds, about 6–8 milliseconds after the start of the a-wave and just before the rising phase of the corneal positive b-wave begins. We suggest that it may represent a hyperpolarizing response of second order retinal neurons.
electroretinogram - cones - second order retinal neurons