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While many researchers are focusing on finding a difference in brains of people with dyslexia, some new research suggests it might not just be in their brains, but in their eyes.

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[♩INTRO ].

Imagine trying to read alphabet soup. None of the letters really stay in place, ‘b's and ‘d's flip around, and you could've sworn there was another ‘e' here a second ago….

That would be confusing, right? Now, imagine the words in your favorite book doing something similar. For some people, this is kind of what dyslexia is like.

People with dyslexia find it difficult to turn written characters into meaningful language. In English, for instance, they might confuse similar letters, add or subtract letters from words, even swap words for similar ones without realizing it -- among many other symptoms. Clinically, dyslexia is considered a learning disability that has been documented in lots of cultures with written language.

Some researchers have estimated that somewhere between 5 and 12 percent of people worldwide have some degree of dyslexia, and it's not linked to any measure of intelligence. Thanks to giant leaps in brain imaging over the past couple of decades, with fMRI and other techniques, researchers have found differences in the brains of people with dyslexia. So many differences, in fact, that there's really not one unifying theory right now.

Reading uses a lot of different linguistic and visual systems in the brain, so weaknesses in different areas could all probably lead to trouble with reading. That being said, many researchers have reported that patients with dyslexia have shown evidence of problems with systems that handle information like phonology, or matching sounds to written characters. In typical, experienced readers, reading activates a few areas in the left hemisphere of the brain, along with what scientists call the Visual Word Form Area, or VWFA.

All these areas are connected by a white matter tract, which is like a highway for information. It's made of the thin fibers of brain cells called axons, surrounded by a fat-rich substance called myelin that helps signals travel. Scientists think that, when we read, this whole system plays a big part in converting the shapes of letters we see into sounds.

And then it stitches them all together and connects that to a meaning. But in fMRI studies with dyslexic patients, parts of these systems, like the temporal cortex, have shown lower levels of activation when they read. And different brain regions tend to show higher activation.

Like frontal areas, for example, which are usually involved in higher levels of thinking and problem solving. So this might be evidence that some brain regions of people with dyslexia are working overtime to try and compensate for a linguistic system that doesn't respond easily or automatically to written characters. They could be processing words in a fundamentally different way.

And many researchers are focusing on the amount of brain cells in certain regions or these connections between them to try and figure out what's different about people's brains who have this disability. However, one piece of new research was making headlines because it suggests that this condition might go beyond brain differences in some patients -- and involve eyes. In a study published in October 2017, two physicists from the University of Rennes compared the retinas of 30 students that were typical readers and 30 students with reported dyslexia.

When you look at something, light shines onto specialized cells at the back of your eye called photoreceptors, which then send signals to your brain. And usually people have a dominant and a non-dominant eye – it's just how we're built. The brain gets a stronger signal from one eye when it's processing visual information. bIn this study, the researchers looked at eye dominance by studying a region of the retina called Maxwell spot centroids.

Essentially, they found that typical readers' eyes were asymmetrical, while the participants with dyslexia had symmetrical centroids. And they proposed that dyslexic patients' eyes were sending conflicting, mirror images of the world to their brain. The example they gave was: the left eye might be saying “this is a b!”, while the right eye is like, “no way, man, that's obviously a ‘d'”.

And these researchers suggested that their discovery could lead to new treatments for dyslexia involving the eyes. But here's the thing: other scientists who specialize in dyslexia research have many critiques of this study. For instance, they mention that these physicists chose one of the symptoms of dyslexia to focus on -- the mirrored letters -- but that's not representative of the whole disability.

It's not even present in every language, like Chinese or Arabic. Dyslexia researchers have also brought up problems with the methodology of the study, like not testing participants for dyslexia as part of the experiment. And they mentioned that scientists have been looking into the relationship between eyes and dyslexia for decades without finding a solid link.

So to go against that general understanding, we need more evidence than just one paper involving 60 students. Now, they didn't voice concerns just to discredit this new research and be snarky. This kind of discussion is really valuable in science, because it can fight against sensationalized media reports.

So, basically, research on dyslexia is an ongoing process. We didn't find a miraculous new treatment overnight, and we're going to need a lot of replication to figure out if differences in eye biology play a role like differences in brain biology. And also, I have an exciting announcement!

Alright, here's the situation, you probably are maybe aware of, the SciShow team and I were talking about a problem that we have where people would be like “what do you want for Christmas” and we would be like, “I don't know man, this is…stressful! You are making me think about stuff!” Do I even need stuff!? This is 2017!

Aren't we like a post stuff world?. But then I was thinking, y'know, there are a few things that I would like to get, or that I've bought for myself, or that people have given me that I really love. And often, it's because like y'know it's emblematic of my love for the universe, the world, or like the existence of life.

So we, at SciShow, put together a collection of artifacts from this universe...we got a limited number of each of those things, and we have put them up at a store called SciShow. Finds. These SciShow Finds are curated mostly by me, there are things that I know that I would love to get in my stocking.

It's a very small list, with just a few things with varying price points. I did my best to only include one science book, it's the one I liked the most of all the ones I read this year, it's called "What is Life" and it makes a very compelling case that biology is like a chemical inevitability. It's like a physical effect of the universe.

It's really interesting. We're probably going to be adding new we find them...throughout the year, and the new ones will replace the current ones, so all of these products are only around for a limited time. You're bound to have friends or family who would love these Mars Socks, trilobite fossils, or this Space Shuttle lapel pin.

And, if not, you might want to get them for yourself or like tell your Mom's or other person in your life, “Hey, this is the place where anything from here would be something that I want.” And know that when you buy from, or other people do, you're also supporting SciShow. Just as you are doing by watching this video. So thank you for doing that. [♩OUTRO ].