Re: Nerve cells in blind mice retain their visual function

Nov 29, 2024 Last reply: 1 year ago 4 Replies
L


Nerve cells of blind mice retain their visual function


> Nerve cells in the retina were analysed using microelectrodes
>
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Summary:
> Using microelectrodes, scientists could show that cells in the retina
> play different roles. The produce different signals, which is important
> for the processing of visual information. These differences are
> remarkably stable and still persist in the retina of blind animals. This
> is important for retinal implants.

I recently heard that the presence of a third type of photoreceptor cell has been detected in the human eye. As well as rods and cones, there is a more primitive light-sensitive mechanism for setting the body clock. People who are completely blind can still maintain a synchronous diurnal rhythm, but if they have had their eyes surgically removed, their rhythms no longer synchronise with daylight.


As far as I know, the extra cells have not yet been identified and their presence is only inferred from their apparent synchronising effect.

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C

I was recently in the room with a relative who was being tested with an unusual method. They were asked to look at a target, close their eyes, and then touch the target. They missed by several inches. Then the Dr. would put a colored filter in front of their eyes *after* the eyes were closed -- and certain colors would improve their ability to find the target. I would not have believed it if I had not watched it personally.

There's a video of the technique here:

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a ringing bell instead of a visual target. The video doesn't point out that the test is done with eyes closed, but it is.

It takes several weeks to adjust to wearing the special glasses that are prescribed; at first my relative could only wear them for two or three minutes lying down in a dark room with eyes closed, before feeling dizzy. After a month or so they had built up to the point of being able to wear them all day. And the glasses* were a big help in treating their symptoms.

I asked the Dr. how colored lenses could have any effect on closed eyes, and they said that there are pathways from eye to brain that are very sensitive to light but do not connect to the visual cortex. It's pretty amazing to see it in action.

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*BTW the colored filters are used only for diagnostic purposes. The glasses themselves are not colored.
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J

I can wake up and know what time it is, sometimes to the exact minute.

But lately, I'm exactly one hour off.

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J

I can sense hot objects in a room by skin feel, thermal IR receptors of some sort. Directionality is poor.

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J

I have pretty accurate time sensing at any time of the day - usually within a few minutes even if I haven't looked at a watch for a few hours. I have no idea why I can do this, but assume my brain has an internal clock somewhere. But why does it work in hours and minutes?

When did your clocks go back an hour?

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