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Restoring Hearing To The Deaf, Sight to the Blind

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It is great that rational thought can allow human beings to do things that were once considered possible only by "miracles". One such technology is the cochlear implant.

Some kinds of hearing loss can be overcome by hearing aids. However, sometimes the inner ear is damaged in a way that stops it from sending signals along the nerves. The idea behind a cochlea implant is this: every modern household already has devices that change sound into electrical signals. Suppose we can figure out what signals are usually transmitted along the nerve for various sounds. If we figure out how to send those signals along the nerve, we can restore hearing in many people who are considered deaf. (For some people, the nerve itself is damaged and this technique will not work.)

In the early 90's, this technology started to be used. Today, there are many thousands of people who have successfully received implants. (There are still issues: for instance, someone who has been deaf for years and gets an implant much later in life has to learn to hear; this is not automatic.)

The technology continues to improve. At the point where it is today, it seems that many people who get the implants (about 80%) can recognize sentences after a year or two. [An interesting aside: The same people have only about 50% success at recognizing monosyllabic words.] (Here is one ref. Google has more.)

When I first read about cochlear implants about 2 years ago, I was really quite shocked. I was not shocked that this was possible, but that the media had been so silent about it. I recommend the MIT Technology Review magazine for articles about such topics. (The free web version does not have full-content.)

The principle behind the cochlear implant (i.e. a device to sense reality and send signals down a nerve) can be used for other senses too. Experiments with black-and-white devices for the blind show that this is and area that can be addressed. It is just a question of time: and the blind will see! Alleluyia!

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...and of course there is a movement against cochlear implants, ...
Yes, I hesitated to mention those creeps in my original post. I'm glad to say that the National Association of the Deaf has "softened" its stance.

I will quote from their site.

In the 1990s, many people in the deaf community worried that cochlear implants might adversely affect deaf culture and the cohesiveness of the deaf community.  Today, the deaf community tends to regard cochlear implants as personal decisions.  Well-regarded members of the deaf community have received cochlear implants.  The NAD played a big role in quieting the controversy in 2000-2001 when it boldly took a balanced position on cochlear implants.
"Boldly" and "balanced", they say! It is bold to say that someone who wishes to cure their deafness is making a personal decision?

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...and of course there is a movement against cochlear implants, on the basis that people would rather be deaf. See, it's a "culture" and a lifestyle choice and... excuse me, I think I'm going to vomit.

Actually, that always made me wonder if they weren't trying to recruit other people into their "naturalist" movement and tell paralyzed people to give up wheelchairs and crawl around on the ground and let people with osteogeneses imperfecta to forgo the bone straightening and lengthening procedures and just stay in padded rooms for their much shorter lives.

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I am awaiting the day when super-senses will be available for non-disabled people like me. I spend way too much time in front of a computer screen, and something to send text directly to the brain would be awesome.

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We do indeed live in an age of wonders. I love news like this. It's so affirming of technology and the ability of man to control and indeed beat nature.

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I am awaiting the day when super-senses will be available for non-disabled people like me. I spend way too much time in front of a computer screen, and something to send text directly to the brain would be awesome.
And you might even use a machine that sends text dirtectly from your brain to your computer. We'll get there.

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I am awaiting the day when super-senses will be available for non-disabled people like me. I spend way too much time in front of a computer screen, and something to send text directly to the brain would be awesome.

There's something to be said for that. Me, I'd like to be able to see in other wavelenghts as well. There are ultraviolet and infrared films, true. But these are more like translations of these frequencies into ones we can see.

BTW the human retina could perceive some of the longer ultraviolet rays, were these not absorbed by the cornea.

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Honda just did a demonstration where a person inside an MRI machine moved his hand in various ways (spreading the fingers, making a "V" sign) and a robotic hand mimicked the movements, based on brain signals picked up by the MRI.

It's a testament to the cool times we live in that some of these experiments begin to seem unspectacular!

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Hey. if anyone wishes to know how the cochlea device (implant) works:

the cochlea is an organ that looks like a snail's shell, and it is the last part of the ear (called the inner ear). there is a membrane stretched throughout the organ, in the middle of it, with variable flexibility (according to the density of fibers in it).

sound that goes into our ear (eventually) passes through the cochlea. Higher frequencies cause the membrane to react most strongly where the membrane is tightest (not flexible) and lower frequencies cause the highest response in the parts of the membrane that are most flexible.

Beneath this membrane there are lots of cells with tiny hairs on their "heads", that sense movement of those hairs and change the voltage of the cell in response (by opening membrane channels that lead certain positive ions into the cell). The voltage change only happen if all the hair of the cells are moving in the same direction (which means only when the vibration of the membrane is the strongest and is typical of the frequency of the sound (BTW, the frequency of the sound is how fast the density of the air/medium the sound passes through changes). The change of voltage is then transfered to neurons, so that each location in the cochlea encodes different frequency (and what the cochlea does, actually is to seperate the sound we hear into all the different frequencies that it's composed of. amazing isn't it).

The frequency of the sound is encoded by the location and the intensity of the sound (how loud that frequency is) is encoded in the firing rate of the neurons that recieve information from the receptors on that location. (Firing rate is the rate at whice the cell produces Action potential).

Sometimes the receptor cells are unable to sense the virbations (I wont go into why), but the neurons are still intact and active. The purpose of the device is to sense vibrations of the membrane and to create electrical pulses that the neurons of that location can relate to (basically to replace the function of the receptors). However, there is the problem of compatibility of the device to the environment of our body, which I'm not sure how it was resolved...

As for devices for the blind, and devices for the cripple, and devices that can read our minds and write text to the screen in response: There is still a LONG way before we can do the last thing. To do that physics must develope, and not neuroscience. The reason is that the information in our brain is encoded by the cells that are active and by the pattern of their activity. To know what you think we need to monitor the cells of your brain. There are 10^11 cells, in layers. it is virtually impossible to connect every cell with an electrode and to sense the voltage changes (unless you want to spend your life without your skull, in a room without jerms of any kind, and you get the picture...) There is no way to know the location of the cell that caused the change of electric field that our device, located outside the skull can receive. There are just too many variables to the problem. The changes in the electrical field that our brain produces are very tiny, and the tiny electrical field that a single neuron produces when it fires an action potential is quickly swalloed in the tissue of the rest of the brain before it travels out.

EEG is a method in which there are electrodes connected directly to the scalp, with a special jell that improves conductivity. In this method we can record patterns of brain activity. These are good to know in general what regions of the brain are active, but not good enough to be able to know the words a person is thinking of, the exact type of movement he plans to do (but it is capable of knowing the direction of it, as I was told).

There are a great deal of research done with electrodes inserted into the brain (of monkeys) that recieve information from aprx. 3 cells at a time, to record the behavior of the cells when the monkey performs different movements and from that information to try to figure our and predict the exact movement the monkey wants to do. This task has not been established yet, because the patterns of the brain as not very simple. sometimes a single cell encodes several things, and it's hard to figure out what is the purpose of each cell (bunch of 3 cells). This method is good for stretching one's arm to a specific direction, but it is not good enough to allow a percise movement of the fingers and to do high percision movements such as holding a fork, and lifting things with it.

As for blind people... in case that the receptors on the retina are damaged, the idea was to insert a tiny chip into the retina, which will communicate with the neurons through electrical signals in response to light (in short it replaces the receptors). However, the device is very far from being usefull... it only allows a person to see a dot of light, or a stain of light. the person cannot identify the form, see colors, etc, and on top of that the device has a problem of being in a biological environment (our body doesnt like strangers and it starts attacking them. covering them up with a scar tissue, or the device can undergo corosion, which is also bad. In short, things are not so pinkish as all of you made it sound (today, a hearing device for the deff, tomorrow, a super human with the ability to jump to the moon and back while reporting the journy straight into a computer using a device that reads his mind)... Especially not in the sight sense.

There is more to talk about in this subject of devices to overcome blindness and about blindness, but some other time...

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Interesting info, Ifat. I now have a better understanding of why it's difficult to figure out the right voltages to send across nerves. In time, someone will figure out a way to figure it out.

Here is speculation that probably belongs to science fiction more than it does to science. Suppose we cannot reproduce the correct voltages, but can reproduce voltages of sufficient variation, and that have a consistent relationship with the external stimuli (i.e. there is a simple relationship between the pitch of the sound and the impulse sent down the neuron; and a simple relationship between the volume of the sound and the impulse sent down the neuron, etc.). In other words, suppose we can translate the sound into a "encoding" that neurons can transmit. If this "encoding" has the level of consistency of the normal human "encoding" but is different from the normal one, then it would be analogous to speaking a different "neuron language". It is possible that the human brain can deal with this, and learn this new "language of sound". [it is also possible that the brain does some of this learning at a certain stage -- before one is 3 years old (say).] Could be that it won't work, but I wonder if there have been experiments that would indicate if it would or would not.

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Here is speculation that probably belongs to science fiction more than it does to science. Suppose we cannot reproduce the correct voltages, but can reproduce voltages of sufficient variation, and that have a consistent relationship with the external stimuli (i.e. there is a simple relationship between the pitch of the sound and the impulse sent down the neuron; and a simple relationship between the volume of the sound and the impulse sent down the neuron, etc.). In other words, suppose we can translate the sound into a "encoding" that neurons can transmit. If this "encoding" has the level of consistency of the normal human "encoding" but is different from the normal one, then it would be analogous to speaking a different "neuron language". It is possible that the human brain can deal with this, and learn this new "language of sound". [it is also possible that the brain does some of this learning at a certain stage -- before one is 3 years old (say).] Could be that it won't work, but I wonder if there have been experiments that would indicate if it would or would not.

Very smart, what you said. It's not so "science fiction" as you think it is.

For example, blind-from-birth people get no stimuli to the visual cortex. Instead neighboring neurons invade into that space, and form meaningful connections with those neurons to encode other types of information, like information about shapes that are attained using touch. So the region that uses normal people to process visual information, uses blind from birth people to understand Braille.

This characteristic of the brain is called "plasticity", and it refers to the brain's ability to change it's architecture in response to stimuli.

In the case of neurons that are responsible for sight: suppose you would use special glasses that would divert the real image a meter to your left, and you would be forced to wear those glasses for, say, 3 months. At first, for someone looking at you from the side, you would turn your head a meter too left to look at an object. But since you still have your hearing sense, your brain would be able to correct this problem, and with time you would start looking at the right direction to see an object again. The wiring in your brain has changed: It has been changed (probably) in the connection between the retina and the brain. So after the glasses are taken off, you would think that objects are not really located where they are located, and using your sense of hearing your brain will re-adjust itself.

However, if you had no reference, you would have no way to correct the mistake.

If someone started to excite the neurons in your cochlea in the opposite order to the actual frequencies, you would simple hear things in a distorted way, I don't know if your brain will be able to correct the mistake, because I'm not sure if the information of frequencies is compared with information from other senses.

An experiment with a frog suggests that you would simply hear distorted sounds but your brain will interpret them as the real ones: A frog's retina has been surgically turned up-side-down. The neurons from the retina connect to the cortex by markers that are determined genetically. The result was that the frog saw the world up-side down. When a fly was above it's head it would leap down to catch it. I think this suggests that since the brain is not counting on light rays to change direction, or on high frequency sounds to appear in the location of the low frequency sounds, that it has no flexibility in interpreting those images/sounds. But the brain does have tremendous plasticity.

Edited by ifatart

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Here's a news story about the using "output" from nerves, rather than providing input.

Claudia Mitchell lost her left arm at the shoulder in a motorbike accident. Her new arm works by detecting movements of a chest muscle that has been connected to the remains of nerves that once went to her real arm.
1. Claudia Mitchell simply thinks to make the arm move 2. Chest muscle movement is picked up by nerves, once attached to the real arm, but now re-wired to its replacement 3. Motors control its movement 4. Unfortunately the 11 pound (5kg) arm and hand do not feel touch

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Here's a news story about the using "output" from nerves, rather than providing input.

Interesting story. I don't understand though how they were able to know which neurons encode what - this has been the major problem in this field. Usually a single neuron in the cortex is used to encode more than just one bit of information. What researchers in this field were trying to achieve for people paralyzed from the neck down was to "read their mind" - literally: to plant electrodes and by a computer, equipped with the program to interpret the electric signal, activate the patient's muscles. However, even after many experiments with monkeys, they were still not able to hack the exact code of the neurons. I suppose going to a lower level (nerve endings) should produce better results, because it is more simple, while the neurons in the cortex process information, the nerve endings that are connected to the muscles represent the result.

But for paralyzed people those neurons are not active.

Here is something interesting from the article:

At present, if Ms Mitchell is touched on the patch of skin on her chest where the nerves to the hand have been re-routed, she feels that her hand is being touched.

People with a limb often experience sensation in their none-existing arm upon touching their face. This is because the conscious sensation of the arm is represented in a deep region inside the brain, but the region receives it's stimuli from the cortex. Now what happens in the cortex is that the activity of neurons that stop being electrically active (because they are not stimulated, because the arm is gone) is overtaken by other neurons, that encode something else. If the neighboring neurons in the cortex are responsible for processing information from the face then eventually touching the face would make that person feel like their arm has been touched.

The intriguing thing in this, for me, though, is what makes certain neurons' activity a conscious experience for us, while others process information that we are not conscious of?

Another puzzle is: well suppose you do find these neurons that are responsible for a conscious sensation, and you explore their biochemistry, and find that what makes them unique is a certain molecule. Why the heck will this molecule, and not any other, be the cause for our experience? Why would the inflow of certain ions produce an experience at all?

When the final outcome of a neuron activity is contraction of muscle - I can understand that. But when the final outcome is movement of ions, nothing more - why would it produce a "consciousness"?

This is a real riddle, a great mystery.

Just thinking aloud here...

Edited by ifatart

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Here is a news-story that indicates we're on the way to sight for the blind.

This story about Jens Naumann who lost both eyes and subsequently regained some vision through artificial eyes is amazing.

*** Mod's note: If link above does not work, here's a link that has some info on the topic. ***

Edited by softwareNerd
Added fresh link

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Here's an interesting article on the subject of vision. It seems that if the nerves of some other organ are provided signals, based on light (e.g. from a camera), the brain is able to learn how to see, using these sensation. This is not to imply that one can see just as well with the tongue as with the eye, but the brain's ability to adapt is quite interesting.

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Here's an interesting article on the subject of vision. It seems that if the nerves of some other organ are provided signals, based on light (e.g. from a camera), the brain is able to learn how to see, using these sensation. This is not to imply that one can see just as well with the tongue as with the eye, but the brain's ability to adapt is quite interesting.

Very interesting, thanks for posting. It seems like the awareness in some sense is determined by the type of object perceived rather by some type of awareness ("type of awareness" like auditory awareness, visual awareness etc'). Fascinating.

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A recent article reports more progress in this area:

Two successful operations to implant the artificial electronic device into the eyes of two blind patients were conducted last week at Moorfields Eye Hospital in London, it emerged today. The device — the first of its kind in the world — incorporates a video camera and transmitter mounted on a pair of glasses.
How cool is that! Edited by softwareNerd
Fixed link

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Miles O’Brien lost most of his left arm in an accident last year. In this link to PBS Newshour (2/12/15), he visits the Johns Hopkins Applied Physics Laboratory and begins to learn how to control the world’s most sophisticated artificial hand by thinking the stuff by which we move our hands: Inspiring.

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Miles O’Brien lost most of his left arm in an accident last year. In this link to PBS Newshour (2/12/15), he visits the Johns Hopkins Applied Physics Laboratory and begins to learn how to control the world’s most sophisticated artificial hand by thinking the stuff by which we move our hands: Inspiring.

That's some cool stuff: particularly seeing how he can manipulate that arm.

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On July 15, 2005 at 11:24 PM, softwareNerd said:

It is great that rational thought can allow human beings to do things that were once considered possible only by "miracles".

This reminds me of some of the extraordinary senses that blind people have that compensate for their lack of sight.

For one, a blind woman I know, once made a comment on my brothers new footwear. She could smell the new leather once he had walked in her home.

Another case was of a young African boy. If I remember correctly, he was born with no eyes, or had them removed at a very young age, for reasons of health complications.

As this boy grew older, he developed his own way of recognizing physical obstacles in his environment. He would let out a chirp like clicking sound with his mouth, which would reflect off of hard objects, and he would literally hear where the sound had echoed back from.

This allowed him to ride bikes, play basketball, and walk around inside or outside, without bumping in to anything.

 

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