The name is absent

By studying the retina, we can characterize responses of its neurons to its normal physi-
ologic stimuli— light. We can also examine how these physiologic signals are transformed
as they are relayed from one set of neurons in the retina to another, and back through neg-
ative feedback loops. By studying the retina, neurophysiologists hope not only to discover
the basis of vision, but to find basic principles that underly systems of neurons that are ap-
plicable to the rest of the CNS. One such principle that is applicable to visual information
processing in both the visual cortex and the retina, is center-surround receptive field antag-
onism (CSRFA). This phenomenon, which enhances contrast around edges in visual scenes,
comes from negative feedback from downsteam neurons with wide receptive fields back to
upstream neurons. It leads to counteracting receptive field areas for a neuron called the cen-
ter and surround. This basic feature has been found in sections of the visual system from its
first stage, in the photoreceptors, all the way up to the visual cortex.

Another interesting feature of the retina as an image detector that is unmatched by any
conventional camera is that it is able to respond to light over a billion fold difference in in-
tensity without saturating. In the retina this feature is called adaptation, and while there
appear to be many mechanisms that underly this response, the basic principle of adaptation
is important in other neural circuits in the CNS, where it is often referred to as gain mod-
ulation [106]. In turn, gain modulation is also similar to the concepts of facilitation and
inhibition.

A logical place to start studying the retina is with the photoreceptors— the neurons
which first transform light stimuli into electrical signals. If we are able to say that we have

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