How the retina works

Hi,

Sorry for the bit of cross-posting, I've had a couple of problems working out the best
place for this post.

I've done quite a lot of googling to find out how the retina works in simplistic terms
but
to no avail.

I have been working at Carver Mead's Silicon Retina in May 91's Scientific American and
have worked out so far:

Light hits the cones and rods, and passed on to the horizonal cells.
The horizontal cells smooths or spacially averages the signal from the rods and cones,
there is also some feedback to them.
The rods and cones along with the horizontal cells send a signal to the bipolar cells
through the triad synapse, which basically takes the difference between them.

So far the effect of this basically detects edges and motion from the original image. Is
this correct so far?

Now I can't find much information on the amacrine and ganglion cells, except that the
amacrine cells perform a similar role to the horizontal cells and the ganglion act as a
conduit to the lateral geniculate in the thalamus.

Could someone kindly expand on that a bit or point me to a site that can explain it in
layman terms?

Any help appreciated.

Wil



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I suggest a decent med school textbook like Kandel and Schwartz. It
may help you beyond a simplistic understanding.

Kal

On Thu, 1 Jul 2004 17:53:47 +0100, "Wil Hadden" <(E-Mail Removed)> wrote:

>
> Hi,
>
>Sorry for the bit of cross-posting, I've had a couple of problems working out the best
>place for this post.
>
> I've done quite a lot of googling to find out how the retina works in simplistic terms
>but
>to no avail.
>
>I have been working at Carver Mead's Silicon Retina in May 91's Scientific American and
>have worked out so far:
>
>Light hits the cones and rods, and passed on to the horizonal cells.
>The horizontal cells smooths or spacially averages the signal from the rods and cones,
>there is also some feedback to them.
>The rods and cones along with the horizontal cells send a signal to the bipolar cells
>through the triad synapse, which basically takes the difference between them.
>
>So far the effect of this basically detects edges and motion from the original image. Is
>this correct so far?
>
>Now I can't find much information on the amacrine and ganglion cells, except that the
>amacrine cells perform a similar role to the horizontal cells and the ganglion act as a
>conduit to the lateral geniculate in the thalamus.
>
> Could someone kindly expand on that a bit or point me to a site that can explain it in
>layman terms?
>
>Any help appreciated.
>
>Wil
>
>
>
>---
>Outgoing mail is certified Virus Free.
>Checked by AVG anti-virus system (http://www.grisoft.com).
>Version: 6.0.712 / Virus Database: 468 - Release Date: 27/06/2004
>

"Kalman Rubinson" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> I suggest a decent med school textbook like Kandel and Schwartz. It
> may help you beyond a simplistic understanding.
>
> Kal

I probably should get a book like that.

What I'm trying to do is make a simulation of essentially the essence of how the various
layers work, and then to later build on the output of that work.

I'm currently at the stage of researching whether my plans make ant sense!
Basically I don't want to be spiralling off doing research on retinas at least until I
know there's merit in building a simplistic model.
To that end I currently need an overview of the various layers.

Wil


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
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On Thu, 1 Jul 2004 17:53:47 +0100, "Wil Hadden" <(E-Mail Removed)> wrote:

>
> Hi,
>
>Sorry for the bit of cross-posting, I've had a couple of problems working out the best
>place for this post.
>
> I've done quite a lot of googling to find out how the retina works in simplistic terms
>but
>to no avail.
>
>I have been working at Carver Mead's Silicon Retina in May 91's Scientific American and
>have worked out so far:
>
>Light hits the cones and rods, and passed on to the horizonal cells.
>The horizontal cells smooths or spacially averages the signal from the rods and cones,
>there is also some feedback to them.
>The rods and cones along with the horizontal cells send a signal to the bipolar cells
>through the triad synapse, which basically takes the difference between them.
>
>So far the effect of this basically detects edges and motion from the original image. Is
>this correct so far?
>
>Now I can't find much information on the amacrine and ganglion cells, except that the
>amacrine cells perform a similar role to the horizontal cells and the ganglion act as a
>conduit to the lateral geniculate in the thalamus.
>
> Could someone kindly expand on that a bit or point me to a site that can explain it in
>layman terms?
>

What you really need is a book like "The Retina: An Approachable Part
of the Brain" by John Dowling, Harvard U Press, 1987. That work is,
in fact, referenced in Mahowald and Mead's "Silicon Retina" paper.
(Incidentally, it is not polite to ignore coauthors when citing work!"

R. Masland has a brief introduction to "The Functional Architecture of
the Retina" in the Dec. 1986 Scientific American.

Just about every book you can find on neurobiology or neurophysiology
or neuroscience or physiological psychology should have a large
section, perhaps a whole chapter, on retinal information processing.
these books are really essential to get a firm understanding of the
anatomy and physiology behind the information processing.

This seems to be a nice web site on the retina
http://retina.umh.es/Webvision/

"r norman" <rsn_@_comcast.net> wrote in message
news:(E-Mail Removed)...
> On Thu, 1 Jul 2004 17:53:47 +0100, "Wil Hadden" <(E-Mail Removed)> wrote:
>
> What you really need is a book like "The Retina: An Approachable Part
> of the Brain" by John Dowling, Harvard U Press, 1987. That work is,
> in fact, referenced in Mahowald and Mead's "Silicon Retina" paper.
> (Incidentally, it is not polite to ignore coauthors when citing work!"

*blush* sorry, was being lazy!

> R. Masland has a brief introduction to "The Functional Architecture of
> the Retina" in the Dec. 1986 Scientific American.
>
> Just about every book you can find on neurobiology or neurophysiology
> or neuroscience or physiological psychology should have a large
> section, perhaps a whole chapter, on retinal information processing.
> these books are really essential to get a firm understanding of the
> anatomy and physiology behind the information processing.
>
> This seems to be a nice web site on the retina
> http://retina.umh.es/Webvision/
>

Thanks for the leads, off down to the library for me then!

Wil


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On Thu, 1 Jul 2004 19:06:46 +0100, "Wil Hadden" <(E-Mail Removed)> wrote:

>
>"Kalman Rubinson" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed).. .
>> I suggest a decent med school textbook like Kandel and Schwartz. It
>> may help you beyond a simplistic understanding.
>>
>> Kal
>
>I probably should get a book like that.
>
>What I'm trying to do is make a simulation of essentially the essence of how the various
>layers work, and then to later build on the output of that work.
>
>I'm currently at the stage of researching whether my plans make ant sense!
>Basically I don't want to be spiralling off doing research on retinas at least until I
>know there's merit in building a simplistic model.
>To that end I currently need an overview of the various layers.
>
In that case, what you need is far more than the introductory type
things I outlined in another response.

If you want your model to be anything other than simplistic, you need
to understand what real neurons do, as opposed to "cartoon" neurons
used in most "neural" models. These are quite fine for research in
information processing, even for research in visual information or
image processing. They are not at all suitable for research in how
the eye actually works.

You need to understand the details of signal conduction down branching
dendrites, about transmitter release by graded signals, about synaptic
plasticity. You need to understand the details of microcircuit
anatomy of the retina. You need to understand the details of
neurophysiology of the retina derived from electrophysiological
studies.

In short, you need to go through some hefty neuroscience text as just
a start and then work your way into the primary literature. I
strongly recommend
Kandel, Schwartz, and Jessel,
Principles of Neural Science
McGraw-Hill, 2000

Squire et al.
Fundamental Neuroscience, 2nd ed
Academic Press 2002

Shepherd
Synaptic Organization of the Brain, 5th Ed
Oxford U. Press, 2003

You also must read
Koch
Biophysics of Computation: Information Processing in Single Neurons
Oxford U Press, 1999

On Thu, 1 Jul 2004 19:06:46 +0100, "Wil Hadden" <(E-Mail Removed)> wrote:

>
>"Kalman Rubinson" <(E-Mail Removed)> wrote in message
>news:(E-Mail Removed).. .
>> I suggest a decent med school textbook like Kandel and Schwartz. It
>> may help you beyond a simplistic understanding.
>>
>> Kal
>
>I probably should get a book like that.
>
>What I'm trying to do is make a simulation of essentially the essence of how the various
>layers work, and then to later build on the output of that work.
>
>I'm currently at the stage of researching whether my plans make ant sense!
>Basically I don't want to be spiralling off doing research on retinas at least until I
>know there's merit in building a simplistic model.
>To that end I currently need an overview of the various layers.

I think you need more than an overview; you need an intimate
understanding of the processing of each of the interacting components.
By this, I mean that a 'simplistic' definition by cell or by layer
will not permit you to design a useful model.

Kal
>
>Wil
>
>
>---
>Outgoing mail is certified Virus Free.
>Checked by AVG anti-virus system (http://www.grisoft.com).
>Version: 6.0.712 / Virus Database: 468 - Release Date: 27/06/2004
>

"r norman" <rsn_@_comcast.net> wrote in message
news:(E-Mail Removed)...
> On Thu, 1 Jul 2004 19:06:46 +0100, "Wil Hadden" <(E-Mail Removed)> wrote:
>
> >
> In that case, what you need is far more than the introductory type
> things I outlined in another response.
>
> If you want your model to be anything other than simplistic, you need
> to understand what real neurons do, as opposed to "cartoon" neurons
> used in most "neural" models. These are quite fine for research in
> information processing, even for research in visual information or
> image processing. They are not at all suitable for research in how
> the eye actually works.
>


Eeek!

What I'm after is something a lot more akin to Mahowald and Mead's Silicon Retina except
done in software.
Would I still need to do into such detail?

Wil


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.712 / Virus Database: 468 - Release Date: 27/06/2004

"Kalman Rubinson" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...

> I think you need more than an overview; you need an intimate
> understanding of the processing of each of the interacting components.
> By this, I mean that a 'simplistic' definition by cell or by layer
> will not permit you to design a useful model.
>

I think you could be right, it might be time to have a rethink!

Wil


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Checked by AVG anti-virus system (http://www.grisoft.com).
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On Thu, 1 Jul 2004 20:17:33 +0100, "Wil Hadden" <(E-Mail Removed)> wrote:

>
>"r norman" <rsn_@_comcast.net> wrote in message
>news:(E-Mail Removed).. .
>> On Thu, 1 Jul 2004 19:06:46 +0100, "Wil Hadden" <(E-Mail Removed)> wrote:
>>
>> >
>> In that case, what you need is far more than the introductory type
>> things I outlined in another response.
>>
>> If you want your model to be anything other than simplistic, you need
>> to understand what real neurons do, as opposed to "cartoon" neurons
>> used in most "neural" models. These are quite fine for research in
>> information processing, even for research in visual information or
>> image processing. They are not at all suitable for research in how
>> the eye actually works.
>>
>
>
>Eeek!
>
>What I'm after is something a lot more akin to Mahowald and Mead's Silicon Retina except
>done in software.
>Would I still need to do into such detail?
>
That seems to be different from what you described earlier.

Do you want to model the real retina or the "Silicon retina"? There
is a big difference. To model the real retina, you must know really
how the cells work. To model the silicon retina, all you have to know
is how that works. And there, I can't help you.