What Blindness Does to the Brain

What Blindness Does to the Brain

Human beings are visual creatures having Our eyes on the front of our heads Provides us with a great amount of depth Perception which is essential for Accurately judging distances our visual Cortex which processes incoming Information from the eyes is much bigger Comparatively speaking to other mammals And even those that also have their eyes On the front of their heads but what Happens to the visual areas of the brain When someone is blind do these areas go To waste or do they come Under New Management so to speak The answer is ridiculously cool let's do This Let's start this video with a real quick Activity that you can do right here and Now and that's understanding your fields Of view so if you're looking straight Ahead you have a left field of view and A right field of view now what's Important to understand is that they are Going to hit different aspects of your Eye so your right field of view is Actually going to come at an angle and Hit the left side of your left eye and The left side of your right eye and then The exact opposite happens with the left Field of view it hits the right side of Your left eye and the right side of your Right eye now they're going to overlap In the center and we call that area Binocular vision now this is where you

Get that greater sense of depth Perception but it's not like it's all of Your depth perception if you go ahead And cover one of your eyes you're still Going to be able to determine distance But as soon as you remove that hand You're going to be able to do that with Just greater accuracy now what's going To happen is photons within the visual Light spectrum are going to hit the back Of your eye in a photoreceptive area Called the retina the retina is loaded With different types of cells but the Two that are most important to us are Going to be rods and cones rods detect Low light sensitivity while cones detect Color and what they're going to do is Work with various other cells inside the Retina to change the photon information Into a language that the brain can Understand I often do this thought Experiment with my students if I was Super rude and I removed part of the Skull and then Shine the flashlight on Someone's brain I ask would they be able To see the light now the answer is an Obvious no and that's because the brain Doesn't have the tools necessary to Process photons as they are instead it Needs to be transduced it needs to be Changed so what will happen in the Retina is it'll work with other cells to Change that information into sodium Potassium neurotransmitters the language

Of the brain then what will happen is Though that signal will leave the retina And go through the optic nerves you're Going to have a right and a left optic Nerve kind of interesting to think about That your eyes are actual extensions of Your brain right the brain grew out These neurological tissues and then Surrounded it in fluids and muscle and Connective tissue and then attached Muscles to it so they can move around And it does that so the brain can see What's around it So the information is going to go from That right and left optic nerve and then Those are going to combine into what's Known as the optic chiasm from there It's going to once again split into the Optic tracts you're going to have a Right and a left optic tract and that is Then going to go deeper into the brain To an area called the thalamus but Specifically inside of there is Something called the lateral geniculate Nucleus or the lgm now this is a Multiple layered area that very specific Tract ways of neurons coming from the Retina will attach into and there is Some visual processing here but not that Much that information will then leave The lgn and go to the back of the brain In the occipital lobe to what's known as The visual cortex now the visual cortex Has five different sub-layers to it we

Call it V1 V2 V3 all the way up to V5 Now V1 is also known as the primary Visual cortex or the striate area and This is the only area that's actually Identifiable with the naked eye the Others need to be understood through a Microscope but what's going to happen is There's a like a gap in the brain tissue Called a sulcus this is called the Calcarine sulcus or calcrine fissure and Bordering that fissure is going to be The primary visual cortex so when the Information gets to that V1 V1 will then Speak to V2 which will speak to V3 to V4 To V5 and all of these will work Together to put and process all that Information together so that you are Then seeing information so what I want To do now is discuss what happens when Blindness starts to interfere with this Visual pathway and how the brain will Respond real quick I want to thank the Sponsor of today's video athletic greens Athletic greens is a nutritional company That makes a nutritional drink ag1 Which Is far more than just a green string and Has become a morning staple for me ag-1 Has 75 different ingredients which Includes vitamins minerals superfoods Probiotics and adaptogens it's Completely replaced my daily Multivitamin but the thing I'm most Excited about are the phytonutrients That are essential to help maintain a

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Neuroplasticity is the brain's ability To reorganize itself both structurally And functionally meaning that it can do One of two things you can either Increase or decrease the amount of Receptors on neurons that bind to Neurotransmitters so like dopamine or Serotonin or you can either strengthen Or weaken the physical synapse itself Now a synapse is the connection between Two different neurons and it's where They communicate so an example I like to Give about this is let's say you learned An instrument as a child but then you Stopped playing that instrument and Never played it for the rest of your Life your brain isn't going to Prioritize that synaptic pathway so What's going to happen over time is They're going to be less receptors to Binaural transmitters on it and then Eventually physically the synapse is Going to weaken and possibly detach or Just start to convey different Information but if you were to continue Playing that instrument then you're Going to see an increase of receptors in The neurons at that synaptic location And the synapse itself is going to Physically become a stronger connection Now it's important to understand that Not all blindness is the same so for Instance maybe you have cortical Blindness which is where there's some

Kind of damage or issue with the visual Cortex and its ability to process visual Information but the rest of the visual Pathway is intact or maybe you had let's Say a brain tumor that affected some Part of the retina or an optic nerve or Maybe the optic chiasm or one of the Optic tracts and depending on where it Is that's going to manifest different Types of blindness meaning that the Brain would have to reorganize itself Differently depending on the type of Lines and in my understanding we don't Yet quite understand it well enough to Say oh you have this type of blindness This is how the brain reorganizes itself Instead we just have a more General Understanding of how the brain Reorganizes itself in response to all Types of blindness now it's also Important to understand that the age That someone goes blind matters Tremendously so if you're a full-grown Adult when the blindness occurs well You're we're probably not going to see Many neuroplastic changes in the brain Now that doesn't mean that they don't Happen it just means that we don't Really have the technology to easily Detect those changes and understand them But if the blindness occurs at Birth or Within the first few years of life we Can definitely detect those changes with Brain Imaging such as an fmri now we've

All heard that when someone loses one Sense that their other senses become Heightened but the question that Researchers had is is this an actual Improvement or is there just less Distractions right if I lose one sense Well there's less to focus on maybe It's not that things improved it's just Easier to focus on the remaining senses Well researchers studying those who've Gone blind early on in life have Realized that there are two plastic Changes that occur inside of the brain In the visual cortex the first is called Cross modal plasticity and this is where Actual structural changes occur in the Visual cortex to better process hearing And tactile Sensations so they're Literally hearing better and literally Feeling better right the brain is not Just wasting that space now the second Type of plastic change is called Multimodal and this one's more subtle It's not that a new structural change Has occurred there was a pre-existing Pathway inside of the visual cortex that Just wasn't being used because Vision Was being prioritized but now that the Visual processing has gone away the Underlying pathway becomes activated so Again we didn't create anything new but Now we're utilizing something that was Already there in a new way way again Heightening both hearing and tactile

Sensations right this makes a ton of Sense again the brain is not just going To go oh we don't we can't see anymore We'll just have a vacant empty space Called the visual cortex and nothing's Going to happen no of course it's going To find a new way to use that space the Body is very much if you don't use it You lose it and the same goes for the Brain but since the brain is such an Important aspect of who we are the body Is gonna find a way to make that work no Doubt thanks for watching everybody I Hope you enjoyed today's episode be sure To click the link in the description Below and that way you can supercharge Your day just like I do with ag1 as Always be sure to like comment subscribe If you feel so inclined and I'll see you In the next video Foreign [Music]

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