Will Light Pulses One Day Restore Hearing Loss?

[glynis]

Will Light Pulses One Day Restore Hearing Loss?

Science has discovered a lot about the healing power of light over the past century. Our bodies produce more Vitamin D when exposed to sunlight. Light treatments can be used to treat certain skin conditions. Some are using light to slow the appearance of aging. Light's even being used to treat mood disorders and depression.

Could light one day be used to treat hearing loss? Let's take a look at what researchers have found.

The Study
Scientists want to know whether light signals can be used to simulate the way sound waves interact with your inner ear. In other words, can they stimulate the nerve cells in the ears with light instead of sound in such a way that the test subject thinks they're hearing sound?

If this sounds far-fetched to you, consider the fact that a brain surgeon can make a sedated patient's arms and legs move by stimulating different parts of the brain. It's similar science but on a much more advanced level.

Scientists began by training the gerbils to jump over hurdles when they heard a certain sound. Once the gerbils were pros as their hurdle-jumping, they took the next steps.

They surgically implanted light-emitting fibers into their test subjects' ears with the intent to use light to impact the nerves in the same way a sound wave would.

The results? The gerbils jumped on cue just as they would have when hearing the sound.

Why This Study Is So Exciting
For decades now we've been using fiber optic cables to transmit information. The most common daily uses for fiber optics are Cable TV and Internet. Unlike sound waves and conventional radio waves that can get distorted with distance, light can carry audiovisual information very long distances with minimal if any interference.

Fiber optics can even produce the High Definition (HD) results that many of us have come to appreciate in our homes.

This light tells your speakers on a computer to produce a certain sound. You hear crystal clear music or voices because of this intricate information that they were able to store and transmit on beams of light.

Now, imagine we could skip the speakers and that light could communicate directly with the nerves in your ear or even directly with your brain. It sounds like science fiction but that's where this research could take us.

We're probably still some decades away from seeing this in use to treat human hearing loss. But it's going to be interesting seeing how these studies progress.

Hearing Technology: A Fast Advancing Science
This gerbil study is just one example of the way that hearing science is fast advancing. Researchers are constantly exploring new ways to improve hearing in those with hearing loss.

Cochlear Implants
Today, with cochlear implants, they use electricity to stimulate the nerve cells, simulating sounds. This mild electric current then travels to the brain. If the thought of electrifying your brain seems a little scary, know that your brain naturally transmits sound through electrical currents generated by your own body.

But cochlear implants have their drawbacks. Those who've had them implanted can't hear the nuances in music that can make a melody so sweet. Voices may not sound completely normal as the electrical signals can't transmit the complexity that is a human voice.

In the way that HD transformed how people watch television, transmitting signals via light may transform cochlear implants, creating a more consistent, natural hearing experience.

Hearing Aids
Hearing aids today use digital technology to receive sound from the environment. In a split second, it converts this sound into digital data. It can then enhance that to meet the hearing aid wearer's unique hearing needs.

If a person has trouble hearing certain frequencies, hearing aids can change those frequencies. It can raise the volume to a level that can be clearly heard. It can filter background or other unwanted noise so that you hear more clearly what you want to hear.

Hearing aids can adapt to various setting to optimize hearing in any environment, on the street, restaurant, phone, living room, concert and more.

Hearing aids today can even connect wirelessly to your TV, smartphone or a sound system to bring the sound straight to your ear.

Light technology may further improve how hearing aids process and transmit sounds to your inner ear and brain for a clearer and more natural hearing experience.

This is just one more way that advanced technologies are helping us hear better every day.

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Categories: Hearing Loss

 

[JohnAdams]

So basically the same concept as a cochlear implant except using fiber optics instead of metal conductors? Sounds over complicated. They use fiber because its imperveous to RF interference and doesnt attenuate as much over long distances. I dont see how this is practical.

I think the golden ticken here is the regeration technology currently being tested. That would make all this other stuff completely irrelevant.

 

[Marlino]

So basically the same concept as a cochlear implant except using fiber optics instead of metal conductors? Sounds over complicated. They use fiber because its imperveous to RF interference and doesnt attenuate as much over long distances. I dont see how this is practical

The reason for the optical stimulation is, that they hope to give patients a better frequency resolution.
As you may know, electrical CIs have just a very limited frequency resolution, which is due to the fact that each electrode stimulates a whole region in the cochlea(the liquid in the cochlear is conductive).
More electrodes and better frequency resolution is not possible this way.

Optical stimulation can be directed better and allows far more channels.

Biggest hurdle is: you need to change the nerves in the cochlear genetically to respond to light pulses.

 

[JohnAdams]

The reason for the optical stimulation is, that it the hope to give patients a better frequency resolution.
As you may know, electrical CI have just a couple frequency channels, which is due to the fact that each electrode stimulates a whole region in the cochlea(the liquid in the cochlear is conductive).
More electrodes and better frequency resolution is not possible this way.

The idea is to use optical stimulation instead, which can be directed better and allows far more channels.
Problem is: you need to change the nerves in the cochlear genetically to respond to light pulses.

but wouldn't the fiber have to terminate in a device that would convert the signals back into electrical impulses? or are we talking about using actual light to try and stimulate nerves?

 

[Marlino]

but wouldn't the fiber have to terminate in a device that would convert the signals back into electrical impulses? or are we talking about using actual light to try and stimulate nerves?

My understanding of optical CIs is, that they shall directly stimulate the nerves attached to the cochlea. But for that they have to be modified to be light sensitive (like the retina maybe, you can "see" sounds then )

 

[GregCA]

My understanding of optical CIs is, that they shall directly stimulate the nerves attached to the cochlea. But for that they have to be modified to be light sensitive (like the retina maybe, you can "see" sounds then )

That doesn't seem to be what is described here: https://spectrum.ieee.org/the-human...urning-light-into-a-tool-against-hearing-loss - which is supposed to generate a signal through the "standard" (unmodified, natural) nerve.

Do you have a source that elaborates on the approach you are describing (which requires modified nerves)?

 

[Contrast]

This is very interesting, but they said decades away.
More like an extremely advance cochlear implant

my bet will be on hair cell regeneration though

 

[Marlino]

That doesn't seem to be what is described here: https://spectrum.ieee.org/the-human...urning-light-into-a-tool-against-hearing-loss - which is supposed to generate a signal through the "standard" (unmodified, natural) nerve.

Do you have a source that elaborates on the approach you are describing (which requires modified nerves)?

Sure, but its in German:

https://www.deutschlandfunk.de/opti...-mit-licht.676.de.html?dram:article_id=422761

In short:
- It' unsure if its technically possible and if so many years away.
- The hope is to go from ~10 frequency channels to >80 frequency channels

 

[dingaling]

Cochlear hair cells are biomechanical transducers and sound waves are physical pressure variations in the air

How can light be substituted when none of the ear or auditory pathway is sensitive to light?

 

[GregCA]

Cochlear hair cells are biomechanical transducers and sound waves are physical pressure variations in the air

How can light be substituted when none of the ear or auditory pathway is sensitive to light?

It is somewhat described in the article I linked to a couple of posts before this one: light exposure, especially focused, can heat up the fluid in the cochlea in specific areas, which expands (from heat): from that expansion you get the mechanical sound wave.

 

[GregCA]

Sure, but its in German:

https://www.deutschlandfunk.de/opti...-mit-licht.676.de.html?dram:article_id=422761

In short:
- It' unsure if its technically possible and if so many years away.
- The hope is to go from ~10 frequency channels to >80 frequency channels

No problem thanks. It's indeed a pretty novel approach! Right now they use a virus to deliver specially crafted genes that encode proteins that enable the nerves to react when they get excited with light.

This is probably quite a few decades away... but very interesting!

 

[Samir]

I will try to clear up some of the confusion. The recent experiment done in Germany was part of a larger study and is based on a different principle than the one that Greg linked to above. One is based on Optogenetics (OG), the other is based on Optoacoustics (OA).

The language of the brain is electricity. Means by which neurons generate action potentials (nerve impulses) is electrochemical. The chemical part of it is absent or not working properly when you have hearing loss due to damaged sensory hair cells. With a regular cochlear implant (CI) you overcome this by directly stimulating the nerves with electricity which polarizes and depolarizes nerve cells and thereby generates action potentials as if the hair cells were intact. So the means by which neurons generate action potentils in a CI patient is exclusively electrical (for sake of simplicity I ignore any stimulation coming in naturally through the ear canal).

OG requires that you genetically modify the neurons to respond to light. You stimulate such neurons by shining light directly on them. So the transmission is optoelectronic. In contrast, OG does not require neurons to be genetically modified. The idea is to generate heat in the cochlear duct, causing the fluid inside to expand and contract by controlling the heat, and thereby generating mechanical waves in the fluid. These waves would still need to move sensory hair cells (assuming some of them have survived) which then stimulates the nerves by electrochemical means just like you have in normal, healthy ears.

The main benefit of both of OA and OG over electric stimulation with regular CI is immensly improved frequency resolution. Thechnically OG would have a great advantage over OA for two reasons. 1. because you can directly stimulate individual neurons, 2. it works even if all hair cells are dead. With OA you are still relying on remaining hair cells, and just like with regular CI you are stimulating a dozen of neurons at once. In short term, OA based approach may become available before OG and it will be better than regular CI. OG requires genetically modifying a person's neurons and this is something unacceptable... for now. More research is needed for sure, but also laws need to be passed that allow such approach. Innovation is usually faster than regulation.

 

[Jim51042]

More research is needed for sure, but also laws need to be passed that allow such approach

Depending on which country the research is taking place. I think China is more amenable to experimenting with human gene modification.

 

[vttbx]

How about a device that shines a light directly into your ear?

https://humancharger.com/

I may have to purchase it after reading this article. It's not cheap.

 

[Contrast]

How about a device that shines a light directly into your ear?

https://humancharger.com/

I may have to purchase it after reading this article. It's not cheap.

omg, this device is full of crap

shining a light into your ear is not going to stimulate your brain.

 

[CricketEars]

Interesting, but wouldn't call this restoring hearing. More of a hearing aid, which is great during the time being until there is a real cure

 

[Spiral]

omg, this device is full of crap

shining a light into your ear is not going to stimulate your brain.

Perhaps regeneration of hair cells will make this kind of cochlear implant irrelevant by the time this would actually be proven or disproven.

 

[Flamingo1]

Yu have a better chance of getting your hearing back practicing voodoo.

 

[85dB T]

Yu have a better chance of getting your hearing back practicing voodoo.

Haha, I agree. I became Catholic and practice Catholicism.

 

[Silvio Sabo]

Perhaps regeneration of hair cells will make this kind of cochlear implant irrelevant by the time this would actually be proven or disproven.

Given the chance of fixing the issue with regrowing hair cells or having an advanced implant that would give me the same kind of hearing as now, I'd choose the implant. Implants don't die when exposed to loud noise and can be swapped and repaired more easily in the future.

 

[Spiral]

Given the chance of fixing the issue with regrowing hair cells or having an advanced implant that would give me the same kind of hearing as now, I'd choose the implant. Implants don't die when exposed to loud noise and can be swapped and repaired more easily in the future.

I guess you'd be in the small minority that would prefer invasive surgery to a quick injection then.

 

[Silvio Sabo]

I guess you'd be in the small minority that would prefer invasive surgery to a quick injection then.

Well, that would depend, among other things, on how invasive the procedure is, the method by which regeneration of hair cells is achieved (gene therapy or a drug) and what the success rate for the two alternatives are respectively. I would imagine that if we were to make an implant that would be able to perfectly mimic the human cochlea we would also have found a way to make putting in such implants less invasive then what inserting cochlear implants are today.

But if you look at it long term the implant solution would be better. An invasive surgery, as bad as it seems, is a temporary inconvenience. But it could be worth it not to ever have to worry about getting tinnitus ever again. This would of course also be true if we were to do regeneration using gene therapy as it would also give one the ability to regenerate hair cells for life.

So it's not as clear cut. The answer simply is: it depends. But the most important thing for me would be if I would have to worry about tinnitus coming back again in the future.