Sunday, February 12, 2012
Sunday, February 5, 2012
Autism and Mirror Neurons
Before I get to the subject of autism, I first need to explain mirror neurons. From the name you can start to gather what these neurons are involved in: imitations, mimicking, and theory of mind (empathy/understanding other peoples feelings/actions). when we pick up a book for instance, certain neurons fire in our brain (motor cortex, etc.) Simple and straight to the point. This is expected. Well, we don't even have to directly be involved in this action to have these neurons fire. Just watching someone else pick up a book causes the same neurons to fire. These are mirror neurons. That is why when someone smiles we smile back without thinking about it. Mirror neurons allow us to imitate others and learn new skills from them. Growing up, we learn a lot of things by watching others - mirror neurons make this possible. One thing unique to humans is the theory of mind. Not only can we "look" into our own mind and try to understand why we do the things we do, we can also miraculously feel the pain of others, put ourselves in their shoes, and try to understand why they do things similar or different than us. We can do this with minimal conscious cognitive effort, but mirror neurons allow this functioning to take place that other animals are not capable of. As well as returning the niceties of a wave or smile, mirror neurons also fire when you see someone in pain. Now, if the same neurons are firing, why don't we feel the pain and only sympathize with what they are going through? Our brains take care of that for us. Our executive functioning skills tell ourselves that it is not happening to us and inhibit the brain from sending the message to our bodies saying that we're in pain. The visual feedback you get from your own body that you see is not hurt, inhibits the signal from actually experiencing pain. One other abstract area that mirror neurons are found to have a role in is understanding metaphors. This is derived from patients with left supramarginal gyrus damage who have apraxia - which is an inability to mime skilled voluntary actions. These patients also have a difficult time understanding action metaphors. This region also has mirror neurons, thus why this connection was made.
Now that you have got a sense of how mirror neurons operate, let me switch back to how this relates to autism.
For those who have autism, they experience difficulty with social skills and interacting with others. They have a hard time processing facial expressing and empathizing with others. Neuroscientists are learning towards a deficiency of mirror neurons as a part of the explanation of what abnormality is taking place in an autistic brain. Researchers have done tests that have supported this hypothesis. There was a study done using EEG (electroencephalography) which picks up brain waves from placing electrodes on the scalp. It is found that the mu wave is suppressed int he brain when you make a conscious movement. Similarly, the mu wave was found to also be suppressed when someone watches another person performing the same movement. When the EEG was done on a child with autism, they had the same suppression of the mu wave when they performed the movement themselves; however, the suppression did not occur normally normally when they were watching the other person. This study has been replicated and supported many times, increasing reliability of this hypothesis. A more recent study has found less connectivity between the visual cortex in the occipital lobe and the mirror neuron region in the prefrontal cortex in patients with autism using fMRI (functional magnetic resonance imaging). Other research has tested the mirror neuron hypothesis with another form of testing using transcranial magnetic stimulation (TMS). TMS creates electrical signals in the brain, creating activity. Researchers stimulated the motor cortex (right before the central sulcus, separating the frontal lobe from the parietal lobe) and then recorded the electromuscular activation in the participants while they watch other people perform movements. Usually, when people watch someone perform movement such as squeezing a ball, the activation in the participant's same hand will go up. The same muscles they would use if they were actually squeezing the ball become "ready" as if they were going to do it. Sustaining the mirror neuron deficiency hypothesis, participants with autism had no increased activation in their muscles when watching other people's movements.
This is some interesting insight to what things in the brain are what neuroscientists think to be linked to autism. This obviously does not explain the reason why their brains are like this in the first place, but it is a step in the direction of finding out in the future. I will continue in a future post on more about mirror neurons and its likely role in autism, but for now this is enough to get you all started. And to reiterate from other posts, these are none of my own personal thoughts or research, I have gotten most of my information from the Tell-Tale Brain by V.S. Ramachandran, which I had mentioned in a previous post on phantom limbs. I'm not trying to say any of this information is my own, I just would like to share what I'm learning :)
Now that you have got a sense of how mirror neurons operate, let me switch back to how this relates to autism.
For those who have autism, they experience difficulty with social skills and interacting with others. They have a hard time processing facial expressing and empathizing with others. Neuroscientists are learning towards a deficiency of mirror neurons as a part of the explanation of what abnormality is taking place in an autistic brain. Researchers have done tests that have supported this hypothesis. There was a study done using EEG (electroencephalography) which picks up brain waves from placing electrodes on the scalp. It is found that the mu wave is suppressed int he brain when you make a conscious movement. Similarly, the mu wave was found to also be suppressed when someone watches another person performing the same movement. When the EEG was done on a child with autism, they had the same suppression of the mu wave when they performed the movement themselves; however, the suppression did not occur normally normally when they were watching the other person. This study has been replicated and supported many times, increasing reliability of this hypothesis. A more recent study has found less connectivity between the visual cortex in the occipital lobe and the mirror neuron region in the prefrontal cortex in patients with autism using fMRI (functional magnetic resonance imaging). Other research has tested the mirror neuron hypothesis with another form of testing using transcranial magnetic stimulation (TMS). TMS creates electrical signals in the brain, creating activity. Researchers stimulated the motor cortex (right before the central sulcus, separating the frontal lobe from the parietal lobe) and then recorded the electromuscular activation in the participants while they watch other people perform movements. Usually, when people watch someone perform movement such as squeezing a ball, the activation in the participant's same hand will go up. The same muscles they would use if they were actually squeezing the ball become "ready" as if they were going to do it. Sustaining the mirror neuron deficiency hypothesis, participants with autism had no increased activation in their muscles when watching other people's movements.
This is some interesting insight to what things in the brain are what neuroscientists think to be linked to autism. This obviously does not explain the reason why their brains are like this in the first place, but it is a step in the direction of finding out in the future. I will continue in a future post on more about mirror neurons and its likely role in autism, but for now this is enough to get you all started. And to reiterate from other posts, these are none of my own personal thoughts or research, I have gotten most of my information from the Tell-Tale Brain by V.S. Ramachandran, which I had mentioned in a previous post on phantom limbs. I'm not trying to say any of this information is my own, I just would like to share what I'm learning :)
Sunday, January 29, 2012
Fun facts
This isn't going to be a long post, but I just wanted to make a few quick points that you might not know about that is something interesting and possibly useful to know:
1. Being in sunlight increases serotonin in the brain. That is why we feel happier when the sun is out compared to when it's dark and rainy.
2. The brain size of someone who is overweight has four percent less volume than those not overweight (from BMI numbers) and looks eight years older. For those who are obese, the brain has eight times less volume and looks sixteen years older. Wow.
3. Someone with an extremely low BMI (such as someone with anorexia) also has a smaller brain than someone with a regular BMI.
BMI = body mass index
If you're interested in figuring out your BMI, you can go here. It's quick and easy!
4. The brain is 60 percent fat! Much of our gray matter, which are the dendrites and cell bodies in the brain, contain large portions of the omega-3 fatty acid DHA (or the more confusing docosahexaenoic acid. Neurons are rich in omega-3 fatty acids, which is why it is important to eat foods with healthy fats, or take a supplement.
For more tips on the health of your brain, check out the book The Amen Solution: The brain healthy way to get thinner, smarter, happier, by Daniel G. Amen.
1. Being in sunlight increases serotonin in the brain. That is why we feel happier when the sun is out compared to when it's dark and rainy.
2. The brain size of someone who is overweight has four percent less volume than those not overweight (from BMI numbers) and looks eight years older. For those who are obese, the brain has eight times less volume and looks sixteen years older. Wow.
3. Someone with an extremely low BMI (such as someone with anorexia) also has a smaller brain than someone with a regular BMI.
BMI = body mass index
If you're interested in figuring out your BMI, you can go here. It's quick and easy!
4. The brain is 60 percent fat! Much of our gray matter, which are the dendrites and cell bodies in the brain, contain large portions of the omega-3 fatty acid DHA (or the more confusing docosahexaenoic acid. Neurons are rich in omega-3 fatty acids, which is why it is important to eat foods with healthy fats, or take a supplement.
For more tips on the health of your brain, check out the book The Amen Solution: The brain healthy way to get thinner, smarter, happier, by Daniel G. Amen.
Friday, January 27, 2012
Phantom Limbs
Something I find fascinating and shows just how truly powerful our brain is compared to our body, is the issues associated with phantom limbs. Some people still have "feelings" where their arm or leg used to be. This does not seem possible because there is no longer anything there to have a feeling, so why does this happen?
There are different brain maps in the brain for different parts of the body. Say, for instance, when part of the arm is removed, there are no longer any nerves for that part of the body, and the brain map in the brain is no longer needed for that particular area. Instead of leaving an empty space in the brain for no activity, the brain wants to utilize any space it does have, so adjacent brain maps start to take over the free space. It is found that brain maps for the face are close to those of the arm, so the brain map for the face starts to infuse into the brain map for the part of the arm removed. Some people will feel an itch and they cannot scratch it because obviously their arm is not there. Well, if they scratch their cheek, they find that it alleviates their itch. Also, if a drop of water is falling down your cheek, it will feel like there is a drop of water going down the phantom arm as well. It's miraculous that you can still have feeling in a part of the body that is no longer there. But it's all in the brain.
There are some people who have paralysis in their phantom limb. Even though the limb is no longer there, they feel as if it is stuck and cannot move. Usually the reason for this is because before the limb was removed, it was in a sling or was not able to move, so the brain becomes accustomed to it. Plasticity makes it so your brain will learn that behavior and neurons have stopped firing to be able to move it, since it is so used to not moving. Well, once the limb has been removed, the brain doesn't automatically shift and say there is no longer a limb there so it is no longer paralyzed. Plasticity allows the brain to change, but it also accounts for us to form habits. The brain is so used to that arm being paralyzed, that it continues to be "stuck" in that way in the brain. A way to change this is through mirror visual feedback (MVF). This sounds crazy and doesn't seem like it would work, but there has been improvement for people with phantom limbs, and also stroke victims. What happens during this type of therapy, is a mirror is placed in a box, while the patient places his real arm in front of the mirror and the phantom arm behind the mirror. If the patient looks at the side of the mirror with his intact arm and moves it, it will appear as if his phantom arm is moving as well. The visual feedback provides feedback necessary for the brain to change and allow the phantom arm to move again because without the arm there, there is no negative feedback to the brain to tell it to stop firing the same way it has always been. So the learned paralysis carries over to the phantom limb because the brain doesn't know any better. Through mirror therapy, the brain "sees" the phantom limb moving, and so the brain can change to start firing again and "move" the limb, unlearning the paralysis it had before. The mirror re-teaches the brain and therefore reshapes it, and alleviates the pain or cramps suffered from the paralysis. It's amazing how our brain can function the same way as if there was still a limb there even though it's not. But it's also amazing, how something so simple as presenting a limb as "moving" even though it's not there can trick the brain into believing it can move again.
A lot of this information I gathered from The Tell-Tale Brain by V.S. Ramachandran. These ideas are not my own; I'm only relaying the information. Also, Ramachandran actually pioneered this type of mirror therapy, and is a highly esteemed neuroscientist and professor at the University of California, San Diego. His work is fascinating, so you should check out some of his books!
There are different brain maps in the brain for different parts of the body. Say, for instance, when part of the arm is removed, there are no longer any nerves for that part of the body, and the brain map in the brain is no longer needed for that particular area. Instead of leaving an empty space in the brain for no activity, the brain wants to utilize any space it does have, so adjacent brain maps start to take over the free space. It is found that brain maps for the face are close to those of the arm, so the brain map for the face starts to infuse into the brain map for the part of the arm removed. Some people will feel an itch and they cannot scratch it because obviously their arm is not there. Well, if they scratch their cheek, they find that it alleviates their itch. Also, if a drop of water is falling down your cheek, it will feel like there is a drop of water going down the phantom arm as well. It's miraculous that you can still have feeling in a part of the body that is no longer there. But it's all in the brain.
There are some people who have paralysis in their phantom limb. Even though the limb is no longer there, they feel as if it is stuck and cannot move. Usually the reason for this is because before the limb was removed, it was in a sling or was not able to move, so the brain becomes accustomed to it. Plasticity makes it so your brain will learn that behavior and neurons have stopped firing to be able to move it, since it is so used to not moving. Well, once the limb has been removed, the brain doesn't automatically shift and say there is no longer a limb there so it is no longer paralyzed. Plasticity allows the brain to change, but it also accounts for us to form habits. The brain is so used to that arm being paralyzed, that it continues to be "stuck" in that way in the brain. A way to change this is through mirror visual feedback (MVF). This sounds crazy and doesn't seem like it would work, but there has been improvement for people with phantom limbs, and also stroke victims. What happens during this type of therapy, is a mirror is placed in a box, while the patient places his real arm in front of the mirror and the phantom arm behind the mirror. If the patient looks at the side of the mirror with his intact arm and moves it, it will appear as if his phantom arm is moving as well. The visual feedback provides feedback necessary for the brain to change and allow the phantom arm to move again because without the arm there, there is no negative feedback to the brain to tell it to stop firing the same way it has always been. So the learned paralysis carries over to the phantom limb because the brain doesn't know any better. Through mirror therapy, the brain "sees" the phantom limb moving, and so the brain can change to start firing again and "move" the limb, unlearning the paralysis it had before. The mirror re-teaches the brain and therefore reshapes it, and alleviates the pain or cramps suffered from the paralysis. It's amazing how our brain can function the same way as if there was still a limb there even though it's not. But it's also amazing, how something so simple as presenting a limb as "moving" even though it's not there can trick the brain into believing it can move again.
A lot of this information I gathered from The Tell-Tale Brain by V.S. Ramachandran. These ideas are not my own; I'm only relaying the information. Also, Ramachandran actually pioneered this type of mirror therapy, and is a highly esteemed neuroscientist and professor at the University of California, San Diego. His work is fascinating, so you should check out some of his books!
Monday, January 9, 2012
Filling in the blanks
Something I find fascinating about the brain is how efficiently it can function and account for missing information. Take for instance vision and our blind spot. There is a sizable blind spot in the retina of your eye where there is an absence of photoreceptors. Well if there aren't any photoreceptors, why can we see things clearly without random things missing? One reason for that is we have two eyes, and the blind spots are in different, non-overlapping locations and can assist each other to get full coverage of the scene in front of you. Now that isn't really the interesting part. What is amazing is that when you close one eye so that you don't have help from your other eye, you obviously experience your blind spot at some point in time, but we never realize this because our brain "fills in" the missing piece to make a continuous coherent image. Crazy right? And don't believe me? Go here and try the test yourself (http://www.ophtasurf.com/en/blindspot.htm). It's freaky, but where an object once was, at a certain distance the object will be in your blind spot so you can no longer see it, but instead of there being an empty hole, the brain patches the hole with the background pattern, so we don't even realize when something is in our blind spot.
This to me sounds crazy because we're seeing something that we're not really seeing. But that is the truth about everything we "see." We don't see anything with our eyes, we see with our brain. Visual stimulation comes in through our eyes, but the brain takes that information and forms a picture for us. Ever wonder why our eyes deceive us? Our brain makes inferences about visual stimulation from previous experiences and knowledge, so it infers a lot of the things we see. If you ever see those sentences that say it twice in a row but you don't notice it, it's not because you're dumb or blind, your brain automatically files that out because it wants to make everything as coherent as possible. You just glaze over it and don't realize that it's there because it would interfere with the overall meaning. No need for the confusion, so just pretend like you didn't see it. Or take for instance sentences that have words with the letter jumbled up, but the first and last letters are the same. We are able to read them fine, with a little slower reaction time, but not much considering the letters are in different positions. The brain automatically gets rid of the clutter and confusion it sees. The brain is smarter than what we imagine. It does it without any conscious effort. Amazing, right?
This to me sounds crazy because we're seeing something that we're not really seeing. But that is the truth about everything we "see." We don't see anything with our eyes, we see with our brain. Visual stimulation comes in through our eyes, but the brain takes that information and forms a picture for us. Ever wonder why our eyes deceive us? Our brain makes inferences about visual stimulation from previous experiences and knowledge, so it infers a lot of the things we see. If you ever see those sentences that say it twice in a row but you don't notice it, it's not because you're dumb or blind, your brain automatically files that out because it wants to make everything as coherent as possible. You just glaze over it and don't realize that it's there because it would interfere with the overall meaning. No need for the confusion, so just pretend like you didn't see it. Or take for instance sentences that have words with the letter jumbled up, but the first and last letters are the same. We are able to read them fine, with a little slower reaction time, but not much considering the letters are in different positions. The brain automatically gets rid of the clutter and confusion it sees. The brain is smarter than what we imagine. It does it without any conscious effort. Amazing, right?
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