How the retina works

"Wil Hadden" <(E-Mail Removed)> wrote in news:(E-Mail Removed):

>
> It would seem odd that light has to pass thought all the other layers
> first, you would imagine that light is being muted going thought those
> other layers. Seeing as we a so extremely dependant on sight this
> would be a very evolutionary big disadvantage.
>
>

Hasn't done us in yet!

Scott

"Wil Hadden" <(E-Mail Removed)> wrote in news:(E-Mail Removed):

>
> "Mike Tyner" <(E-Mail Removed)> wrote in message
> news:0U%Ec.22141$(E-Mail Removed) hlink.net...
>>
>> "Wil Hadden" <(E-Mail Removed)> wrote
>>
>> > 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.
>>
>> It would be useful to review research into the various "entoptic"
>> phenomena like afterimages, color persistence, and edge detection, as
>> well as comparative animal physiology.
>>
>> Simpler models are preferred, as long as they explain the observed
>> phenomena.
>>
>> -MT
>>
>>
>
> That is exactly what I am trying to model, I have more of an interest
> in edge detection than in the make up of the retina in a physiological
> sense.
>
> Do you know of any models I could look at?
>
> Wil
>
>
>
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>

Definately pick up "Vision" by Marr. He uses "primitives" available at
the ganglion cell layer, and arranges them to detect more features, like
edges. Good stuff.

Scott

"Scott Seidman" <(E-Mail Removed)> wrote in message
news:Xns951AC115BB7EAscottseidmanmindspri@130.133. 1.4...
>
> Definately pick up "Vision" by Marr. He uses "primitives" available at
> the ganglion cell layer, and arranges them to detect more features, like
> edges. Good stuff.
>
> Scott


From who I've seen from the Silicon Retina this already happens in the horizontal layer,
I was guessing that ganglions refines what has been found. Is this possible?

Wil


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in article (E-Mail Removed), Wil Hadden at (E-Mail Removed) wrote on
7/2/04 11:05 AM:

>
> "r norman" <rsn_@_comcast.net> wrote in message
> news:(E-Mail Removed)...
>> On Thu, 1 Jul 2004 20:17:33 +0100, "Wil Hadden" <(E-Mail Removed)> wrote:
>> 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.
>>
>>
>>
>>
>
> You are correct, I am really after something more aligned to the silicon
> retina, but I
> also want to understand it's design in relation to a real retina and to try to
> understand
> the myriad of amacrine cells. To be honest though my research will not be
> going in to PhD
> detail!
>
> I have to say though I went though the site you suggested and it is extremely
> good, there
> is a pdf download that gives a fantastic overview of the retina and is exactly
> the sort of
> thing I was after.

So you probably already got:

Helga Kolb's overview "How the Retina Works"
available at:
http://webvision.med.utah.edu/index.html


A nice website on the evolution of the retina is:

http://www.pigeon.psy.tufts.edu/avc/husband/avc4eye.htm

As for the "upside down design", Stephen Palmer writes in the book "Vision
Science: Photons to Phenomenology":

====
The reason for this unusual arrangement is probably that the enzymes that
are needed for pigment regeneration are in the pigment epithelium, which is
opaque. Because the receptor disks must be adjacent to this vital
biochemical resource, they must also be at the back of the retina.
====

But then there is the head-foot molluscs retinal organization...(shrug).

>
> I also have a collection of papers about neurons on order it includes "The
> Functional
> Architecture of the Retina" in the Dec. 1986 Scientific American, though I
> just found out
> I think you can get those old papers from the sciam site, anyway definitely
> worth a read.
>
> All in all thanks for your responses, they have definitely helped me refine
> what I am
> looking for.
>
> Wil
>
>
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"Michael Olea" <(E-Mail Removed)> wrote in message
news:BD0B8241.A7FC%(E-Mail Removed)...
> So you probably already got:
>
> Helga Kolb's overview "How the Retina Works"
> available at:
> http://webvision.med.utah.edu/index.html
>
>

Yep that's the same one, it's not half bad.

> A nice website on the evolution of the retina is:
>
> http://www.pigeon.psy.tufts.edu/avc/husband/avc4eye.htm
>

That seems food as well, thanks!

> As for the "upside down design", Stephen Palmer writes in the book "Vision
> Science: Photons to Phenomenology":
>
> ====
> The reason for this unusual arrangement is probably that the enzymes that
> are needed for pigment regeneration are in the pigment epithelium, which is
> opaque. Because the receptor disks must be adjacent to this vital
> biochemical resource, they must also be at the back of the retina.
> ====
>
> But then there is the head-foot molluscs retinal organization...(shrug).
>

Do I want to know ?

Wil


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"MZ" <(E-Mail Removed)> wrote in message
news:tpudnQhUY_kMYmPdRVn-(E-Mail Removed)...
> > Lateral inhibition looks promising I must say. It resembles a self
> organising map in
> > neural networks and seems to be very useful!
> > I'm presuming that the horizontal and amacrine cells exhibit lateral
> inhibition, so
> > there's no getting away from it!
>
> It may be worthwhile to start with Hartline's work on limulus and advance
> into the many subsequent modelling (etc) papers. Passaglia and Barlow '98
> is an interesting one.
>
> Relevance to mammalian retina? Sure, why not?
>
>

Excellent, I've had a look at a website detailing Harline's work and it states that
lateral inhibition is only used for edge detection, though I know it's also used for
motion detection.

Is that all it's used for or are there other applications.

My research since that posting has pointed me at Adaptive Resonance Theory, which looks to
formalise an implemntation of lateral inhibition in a biologocally plausable manner.

Can someone remind me of the method which is basically the same as ART 1 and ART 2 put
together? I can't remember it off the top of my head.

Wil


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"Wil Hadden" <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...

>
> Excellent, I've had a look at a website detailing Harline's work and it states that
> lateral inhibition is only used for edge detection, though I know it's also used for
> motion detection.
>
> Is that all it's used for or are there other applications.
>
> My research since that posting has pointed me at Adaptive Resonance Theory, which looks to
> formalise an implemntation of lateral inhibition in a biologocally plausable manner.
>
> Can someone remind me of the method which is basically the same as ART 1 and ART 2 put
> together? I can't remember it off the top of my head.
>
> Wil


Hi Wil, I just happened upon this thread. Here are some thoughts and
suggestions .....

1 - take a look at Werblin's site. He got his PhD with John Dowling,
and was the first to record intracellularly from all cell types in the
retina. He's spent the intervening years trying to work out the
details of interactions between various cell types. He has some
"retina movies" - [always a showman].

http://mcb.berkeley.edu/faculty/NEU/werblinf.html
http://mcb.berkeley.edu/labs/werblin/RetinaVideos.htm

2 - regards how horizontal interactions within the retina affect
sensitivity, take a look at old papers by Werblin and Larry Thibos -
about 1977-ish [???]. Lateral inhibition from horizontal cells to
bipolars and back to photoreceptors is responsible for both adjusting
gain/sensitivity, and also for forming the center-surround receptive
fields of bipolar cells.

3 - regards why the vertebrate retina is "upside-down", IIRC, it's
possibly because ... of all cells in the retina, the photoreceptors
have the most severe metabolic requirements and are adjacent to tissue
that can help nourish them. But you might check this. Even so, tiny
cells are basically transparent, so their being physically located
between the cornea and photoreceptors is not as important as one might
imagine.

4 - old ideas were that the amacrine cells were highly
motion-sensitive [Werblin again] and factored into the responses of
motion-detection outputs from the retina. IIRC, Barlow and Levick
[1950s or 60s or so] had a model for for how motion-oriented cells in
rabbit retina might work - basically time-dependent feedforward
signals in the amacrine cell layer.

5 - you might also be interested in one of the all-time great
classical papers about retinal and tectal cell responses - "What the
Frog's Eye Tells the Frog's Brain":

http://www.ai.mit.edu/people/phw/6xxx/lettvin.html

- hope this helps a little ....