<p>The difference is that ganglion neurons are responding directly to phenomena <em>in</em> their receptive field. That is, the on-center, off-surround ganglion cells are directly connected to the photoreceptors at the center and in the surround. The explanation for off-surround is that photoreceptors at the periphery will directly hyperpolarize the ganglion cell.</p>

<p>Extraclassical receptive field effects are about explaining how a neuron (e.g., in V1) responds to phenomena <em>outside</em> its receptive field. That is, it is possible to map the entire portion of the visual field that it is hooked up to, e.g., by passing a stimulus across the visual field and noting all regions where spike trains are evoked by the stimulus. This portion of the visual field is known as the classical receptive field. It turns out that V1 neurons can be influenced by stimuli <em>outside</em> their classical receptive field. Unlike "end-stopping" in retinal ganglion neurons, this cannot be explained by hyperpolarizing input at the periphery of the receptive field, because the stimulus causing the end stopping is <em>not</em> in its receptive field in the first place.</p>

CC BY-SA 4.0
2020-05-09T13:54:26.560Z
2020-05-09T13:54:26.560Z
Que
<p>Rao and Ballard (1999) start their <a href="https://www.nature.com/articles/nn0199_79" rel="nofollow noreferrer">paper</a> by stating that extra-classical receptive fields, which exhibit the phenomenon of end-stopping are difficult to explain. They show that in an idealized predictive coding model trained on natural images, the "neurons" at a higher level in the model have a receptive field that exhibits end-stopping; therefore, if neurons in the brain are implementing predictive coding, they would exhibit this phenomenon.</p>

<p>What I don't understand is this - why is it difficult to explain extra-classical receptive fields? After all, retinal ganglion neurons that are on-center will also exhibit "end-stopping" if a stimulus extends outside of the center, and the explanation for that receptive field is straightforward: the photoreceptors at the periphery hyperpolarize the ganglion cell, whereas those at the center depolarize it. Why can't a similar story be told about cortical neurons? Why was the predictive coding framework needed to explain end-stopping?</p>

<neuroscience><theoretical-neuroscience><computational-modeling>
Extra-classical receptive fields are surprising, but retinal ganglion receptive fields are not. Why?
Que
# Extra-classical receptive fields are surprising, but retinal ganglion receptive fields are not. Why?

(Asked by: username_0 on 2020-02-23)

Rao and Ballard (1999) start their [paper](https://www.nature.com/articles/nn0199_79) by stating that extra-classical receptive fields, which exhibit the phenomenon of end-stopping are difficult to explain. They show that in an idealized predictive coding model trained on natural images, the "neurons" at a higher level in the model have a receptive field that exhibits end-stopping; therefore, if neurons in the brain are implementing predictive coding, they would exhibit this phenomenon.

What I don't understand is this - why is it difficult to explain extra-classical receptive fields? After all, retinal ganglion neurons that are on-center will also exhibit "end-stopping" if a stimulus extends outside of the center, and the explanation for that receptive field is straightforward: the photoreceptors at the periphery hyperpolarize the ganglion cell, whereas those at the center depolarize it. Why can't a similar story be told about cortical neurons? Why was the predictive coding framework needed to explain end-stopping?

**Tags:** neuroscience, theoretical-neuroscience, computational-modeling


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## 1 answers

### Answer by username_0 on 2020-05-09. Score: 0 | Accepted answer

The difference is that ganglion neurons are responding directly to phenomena *in* their receptive field. That is, the on-center, off-surround ganglion cells are directly connected to the photoreceptors at the center and in the surround. The explanation for off-surround is that photoreceptors at the periphery will directly hyperpolarize the ganglion cell.

Extraclassical receptive field effects are about explaining how a neuron (e.g., in V1) responds to phenomena *outside* its receptive field. That is, it is possible to map the entire portion of the visual field that it is hooked up to, e.g., by passing a stimulus across the visual field and noting all regions where spike trains are evoked by the stimulus. This portion of the visual field is known as the classical receptive field. It turns out that V1 neurons can be influenced by stimuli *outside* their classical receptive field. Unlike "end-stopping" in retinal ganglion neurons, this cannot be explained by hyperpolarizing input at the periphery of the receptive field, because the stimulus causing the end stopping is *not* in its receptive field in the first place.


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