AUTISM IN THE LIGHT OF MIRROR-NEURONS
The best description of autism I have found relies on defining the condition by its symptoms, divided into two categories: social-cognitive and sensorimotor.
Mental aloneness, lack of contact with the world, absence of emotional empathy for others, no outward sense of play, no make-believe, no playfulness, hightened interest in their inanimate surroundings which may even become obsessive, difficulty miming, learning a language, using the prepositions "I" and "you".
Specific sensory stimuli can be found to be highly distressing, fear of novelty and change, obsessive insistence on sameness, routine, monotony, to-and-fro rocking of the body, repetitive hand movements; flapping and self-slapping, sometimes elaborate, repetitive rituals.
In the frontal lobe of our brain there are neurons that fire when we perform a specific action: for example raising our hand. These same neurons however, fire also when we simply observe someone performing the same action: raising the same hand, even when we are immobile. These mirror-neurons, allow us to predict simple goal-directed actions of others .
Mirror-neurons are one of the important mechanisms that allowed human beings to develop language and culturally evolve: they in a way create a mental-simulation of what we see, allowing us to copy other people's actions, a baby can stick its tongue out hours after birth if it observes it's mother doing the same .
The ability to observe someone performing an action, has been suggested to have been the first step towards the birth of our own self-consciousness. Turning this observation inwards, towards ourselves, may have been the start of self-awareness.
Mirror-neurons allow us to develop a Theory of Mind: the ability to attribute intelligent mental beingness to other people: to understand that fellow human beings behave the way they do because they too have thoughts, emotions, ideas, motivations of more or less the kind you yourself have. 
OBSERVATION: HOW MIRROR NEURONS MAY RELATE TO AUTISM
Many autistic children have difficulty miming and imitating other people's actions. Empathy, intention-reading, mimicry, pretend play, language learning are all affected in autism, and are all closely related to the function of mirror-neurons.
Many of the social-cognitive symptoms in autism, may be seen as the result of a deficient Theory of other Minds: a seeming lack of self-awareness, the absence of understanding of others and lack of social empathy for them, the difficulty in understanding and properly using the prepositions "I" and "you" may also suggest that they lack fully-mature self-representation to understand the true distinction between them.
This connection lead to the hypothesis that autism may be due to mirror-neuron malfunction.
SOME STUDIES THAT EXPLORED THIS HYPOTHESIS
1. MU WAVE SUPPRESSION
Mu-waves are brain waves that are suppressed when a person makes a volitional movement, and also when a person sees someone else performing the same movement, they are closely linked to the mirror-neuron system .
In the study, medium-functioning autistic children had their mu-wave brain waves observed while performing a simple task, and when observing the task being performed. Unlike non-autistic children, who had suppressed mu-waves when both performing and observing the task, the autistic children had suppressed mu-waves when performing the task themselves, but not suppressed mu-waves when watching some else. This supports the hypothesis that their mirror-neuron system is faulty. 
When a non-autistic individual watches someone squeeze a ball, there is a tiny but measurable increase in the action-readiness of the muscles that would contract they were themselves performing it . This is because the motor system simulates the perceived action and at the same time suppresses the spinal motor signal, but there is a tiny trickle that still reaches the muscles. Autistic subjects show no increased muscle potentials in the same circumstances.
HOW CAN THIS HELP
The most important result from these studies and this theory for explaining autism in the terms of mirror-neurons is how it can benefit individuals with ASD. These are some mechanisms:
1. EARLIER DIAGNOSIS
One of the major problems with autism is that it usually takes a very long time to diagnose, yet the earlier therapy starts, the better the chance for minimising the symptoms. Measuring the amount of mu-wave suppression can be a early diagnostic tool for screening the disorder in early infancy.
Biofeedback is a therapeutic tool which uses a physiological signal from a subject's body or brain which is tracked by a machine and then represented back to the subject through some sort of external display . The goal is for the subject to concentrate on trying to nudge the signal up or down, gaining some conscious control over it. For example, the heart rate may be expressed in the form of a candle flame which the subject tries to make smaller by lowering their heart rate. It has been used for pain control, heart rate control, and it is suggested to be used for mu-wave suppression too.
3. DANCE THERAPY
Although dance therapy has been used to try to help individuals with ASD, it can be modified in a way that is targeted at improving the mirror-neutron system, and therefore, can be predicted to help with symptoms of autism. If the individuals not only danced to a rhythm, but tried to imitate model dancers moving in a room of mirrors with multiple reflections of them and the dancers, it may help in increasing the impact on the mirror neuron system. 
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