By Sarah Friedman
When a five year old child is learning to tie their shoe, or a two year old is learning to hold a fork, or a sixth month old is learning that a smile relates to being happy, they require input from the outside world to understand what these things mean. The child learns the meaning of the action by watching other people and incorporating the knowledge into their own frame of reference. So what happens when something blocks this passage of information? According to the Mirror Neuron theory of autism, it can have devastating effects on a child’s ability to learn and relate.
Our brain cells, or neurons, communicate by releasing chemicals called neurotransmitters. Measuring when, where, and how much neurotransmitter is released can demonstrate, in essence, how we think. Mirror neurons are neurons that respond both when a person is doing something, as well as when a person watches the same act being done by another person. For example, the mirror neurons of a normal person will fire when they clap their hands, as well as when they watch someone else clap their hands. Disruptions in this mirroring system may be a cause of the social ineptness and deficits in learning through imitation seen in the autistic population.
To say that most autistic individuals lack general social skills is somewhat of an understatement. For anyone who has raised or worked with an autistic person, the idea of socialization is one of the biggest aspects of dealing with the condition. The concept of being able to empathize, or simply register another person’s significance, as well as the ability to use the wealth of information in life learned through other people are often missing.
The mirror neuron system was discovered in the 1990s’s when neuroscientist Giacomo Rizzolatti found that a monkey’s neurons fired in equal amounts when it picked up peanuts, as when it watched a human pick up peanuts (Ramachandran & Oberman, 2007). The thought was that these neurons, by acting like mirrors, provided understanding of the intent behind the action of someone else thereby producing a duplicate reaction in the monkey watching (Ramachandran & Oberman). The same was found to be true for humans according to several studies.
A couple years ago a study came out led by Mirella Dapretto (2006) which compared the brains of autistic children to non-autistic children. They measured blood flow to certain areas of the brain using an MRI machine as the children watched or imitated different facial expressions. It was found that every autistic child, when watching the expressions, showed far less activity in the pars opercularis of the inferior frontal gyrus, a part of the brain which provides humans the ability to understand each other’s intentions by observing others’ actions or imitating their behavior. The non-autistic children had equal amounts of activity whether doing or watching. The intensity of each child’s autism was rated as well and it was found that children with more severe autism had even less activity.
Another study by Oberman et. al. (2005) used an electroencephalogram (EEG) to measure brain activity in certain regions by looking at mu waves, which are brain-wave patterns which are suppressed or blocked when the brain is busy doing, seeing or imagining an action. When a person does something voluntarily or watches this same action being done by another person, the waves are suppressed. The children in the study were measured as they watched and performed different acts. In the autistic children though there was suppression of mu waves when they themselves performed the action, there was little to none when watching others. The non-autistic children showed suppression during both.
Yet another study, led by Luigi Cattaneo (2007), used an Electromyograph (EMG) to measure muscle activity in a muscle used to open the mouth called the mylohyoid. Both autistic and non-autistic children were measured as they watched someone else reach for and grab food, and then as they did it themselves. The non-autistic children had muscle activity while watching and performing the action, whereas the autistic children had no activity while watching, or while grabbing for food themselves. Their muscles only showed activity when it came time to eat. The implication being that autistic children not only had an issue with the intention behind someone else grabbing the food, but also failed to make the connection between their own motor actions.
The term ‘broken mirror’ is often used to describe this theory because of the idea that the system in the brain that allows a person to understand another person, to mirror their actions or feelings, is broken. It’s like a two way street with an obstruction blocking one lane making incoming information about the world much more difficult to obtain and understand. Think about how much in life we learn from other people simply from watching and through imitation. Imagine the many deficits a person with an impeded ability to do this would have. The impact of not being able to relate to or understand others can have a shattering effect on human comprehension and emotionality. Common aspects of autism like issues with language development and speech, inability to communicate non-verbally, the inability to recognize and understand emotions and intentions in others, the general lack of desire for social relationships, and the inability to think abstractly are all things that could be a result of this faulty system (Ramachandran & Oberman, 2007).
This is not to say that the Mirror Neuron theory explains all aspects of autism. Scientists like Helen Tager-Flusberg, Ph.D contend it does not explain aspects like the repetitive ‘stimming’ behavior, hypersensitivity to sound and touch, poor motor coordination, or the high rate of mental retardation often co morbid (Dingfelder, 2005). Along with that, most of the research comes with the limitation of being done solely on higher functioning subjects with an inability to say whether the results can be generalized to the entire autistic population (Dapretto, 2006).
If, however, the theory can be confirmed through further research it could open a new door in the diagnosis and treatment of autism. Children could be diagnosed as early as infancy by looking at mu wave suppression, allowing for behavioral treatment to begin earlier (Ramachandran & Oberman 2007). If a chemical imbalance causes the disability then perhaps compounds can be found that either stimulate under working neurons or mimic what they do (Ramachandran & Oberman). It even opens the door for biofeedback to be used as it teaches a person to control their own responses to stimuli (Ramachandran & Oberman). Studies on this topic are underway and it will be interesting to see how effective a method it is.
In the end there might not be one decisive answer to autism. Deficits in the mirror neuron system could themselves be a side effect of some greater problem not yet identified. Or perhaps the research going on right now will expand our understanding of the system to include the aspects that don’t seem relevant now. Whatever the next round of research shows, there is no denying that a connection exists between social understanding and deficits in particular brain function. And though the science itself is still new, hopefully it will provide for better ways of dealing with one of life’s biggest mysteries.
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