Mirror Neuron System in Autism Spectrum Disorder

Statistical research across several states in the United States reported that in 2009, 1 in every 150 children was identified with Autism Spectrum Disorder (ASD). This number increased by 2014 to 1 in every 59 children (CDC, April 26, 2018). This increase in only five years presents the urgency for the scientific community to find accurate diagnosis techniques and develop a full understanding of the reason behind Autism Spectrum Disorder. Researchers have shown that typically developed children learn through observing actions and communicating them through imitation. Children at preschool ages imitate even unnecessary steps to reach a goal of a skill if they observed an adult performing these steps (Ben Kenward et al, 2010). That is to say that children develop socially and learn skills through observing and imitating other actions. However, children with ASD had been reported to have uninterest on people around them. Children with ASD tend to avoid eye contact with others and to not to respond to pointing, waving, or the calling of their names (American Psychiatric Association, 2013). Scientists are currently arguing the possibility of a biological abnormality in the brain, specifically a dysfunction in the Mirror Neuron System. The Mirror Neuron System dysfunction may be causing people with autism to behave abnormally, delaying their development. This paper will work on reviewing original literature from the past decade to identify the differences between the functioning of Mirror Neuron System in typically and atypically developed brains.

The biological mechanism that enables imitation was first located in macaque monkeys, particularly, in the F5 area or the premotor cortex that is responsible for comprehending and imitating actions. The neurons in this area activate each time a monkey would perform or observe a meaningful action (Gallese V et al, 1996). Those neurons were then called the Mirror Neuron System and were noticed, using the Functional magnetic resonance fMRI, in the human brain. Similar to macaque monkeys, these neurons in human brain activates in the premotor cortex during action observation (Iacoboni, M et al, 1999). This was reported again in 2010, where typically developed adults were reported to experience brain activations in the premotor cortex while observing meaningful actions. Adults with autism spectrum disorder were found to experience the same activations. However, these activations were not only in the premotor cortex but also in the ipsilateral cerebellum. This finding argues that there is no dysfunction in the Mirror Neuron System in people with autism. Nevertheless, the autistic brain encounter difficulties in interpreting or proccing the stimulus and the information presented, especially that there were no differences reported between the activation of both typically Developed and Autism Spectrum Disorder groups when they were performing the actions they observed (Martineau, J et al, 2010). Though the interpretation of this findings explained a relevant reasoning behind the atypical activation in the autistic brain, using a sample of adults only in this experiment makes it inaccurate to make a statement based on this research about the whole Autism Spectrum Disorder community. Also, because of the sampling, this experiment does not narrow the question of whether or not people who suffer from autism experience dysfunction in the Mirror Neuron System.

Other research teams took into account the details of the brain proccing of the “other” biological actions versus the brain processing of the “other” states of mind, basing their investigation on the differences between the Mirror Neuron and the Theory of Mind processing, indicating that there is a difference between both systems. The theory of mind is the process of determining other intentions and feelings, while the Mirror Neurons work for the brain to be able to interpret and assume the reasons behind the physical actions. From that, they detected the blood flow between the areas in the brain that are responsible for Theory of Mind and those that are responsible for the Mirror Neuron System. The blood flow between these areas was found in both autistic and typically developed adolescents. Nevertheless, when comparing the highly functioning autistic brain or people who experience less severe autism traits with those who experience highly severe symptoms, there was more communication between the Theory of Mind and the Mirror Neuron System areas in adolescents with severe autism than those with high functioning autism (Fishman, I. et al, 2014) This opened a new window of several questions, where it added into the discussion the possibility that the Mirror Neuron System activation could differ based on the severity of the autistic symptoms, referring to the importance of taking into account that the Mirror neuron System in people with autism functions in various ways.

Concluding that there are no differences in the mirror neuron system activation between typically developed and high functioning autism was investigated earlier than 2014, particularly in 2009. However, it was reported that there are no differences between Typically Developed and highly functioning participants. In fact, both groups showed the same activation in all the experimental conditions. Either observing meaningful, non-meaningful or performing an action the activation of Mirror Neuron System indicated no differences between the groups (Raymaekers R, 2010). This made it clear that the Mirror Neuron System has no role in the communication difficulties that adolescents with high functioning autism experience. A study to evaluate this judgment considered comparing the Mirror Neuron System activation of adults and adolescent participants. A measurement of the activation, using EEG or Electroencephalography, was performed when the participants were observing as well as imitating the actions presented to them. Based on that no significant differences in the Mirror Neuron System activation were found between typically developed and severe Autism Spectrum Disorder participants. However, participants with severe Autism Spectrum Disorder failed to imitate the action presented to them. It was then, suggested that the activation level of the mirror neuron system does not indicate accurate information to diagnose Autism. Nevertheless, the activation of the mirror neuron system could provide us with information to indicate the severity of autism in a particular person. Even though no vital differences in the activation of the mirror neuron system between the groups was found, individuals with less mirror neuron system activation were associated with more communication severity (Fan, Y.-T. et al, 2014). In summary, these studies convey that a measurement of the mirror neuron system activation could lead to misdiagnosis because it is indicating different activations depending on the group or the individual statue.

An attempt to explain the reason behind the difficulty that people with severe autism encounter when attempting to imitate an action, found that students with high autistic traits, in participants from the standard students’ population, experienced the same mirror neuron system activations when observing a static hand as when observing a meaningful hand movement. This finding was not the same when measuring mirror neuron system activation in less severe autistic students. It was determined that the mirror neuron system activation in less severe autistic students was more when they were observing meaningful actions than when observing the static hand. The interpretation of this finding suggested that the autistic brain may be encountering difficulty in processing information. Therefore, when presented with a single stimulus it was easier for the brain to process what is being seen. Nevertheless, presenting a hand movement, we are exposing the students into more than one stimulus which is difficult for the autistic mind to perceive (Puzzo, I., 2010). This conclusion was made without accounting for the argument that there may be differences between the way females and males with ASD communicate. Reporting such a result could be for the reason that the sample included females and males participants. Females who experience ASD are estimated to have stronger action perception than males. Therefore, females may encounter fewer communication difficulties than males (Mandy W et al, 2012, Lai MC et al, 2011). Accordingly, the results may have been affected by females extremely high or low mirror neuron system activation, which lead to exaggerated results. Other researchers suggested that children with autism show difficulty in imitating if they could not identify with the presenter of the actions, indicating that the mirror neuron system would activate in the same way as the typically developed group if the actions presented by familiar people (Oberman, L. M. et al, 2008)

The literature that this paper present is for the purpose of contributing to improvements in conducting future research that will test the effect of mirror neuron system on people with Autism Spectrum Disorder. By presenting the different results and findings, each literature was documented because of inconsistency or disregarding of factors like Autism Spectrum Disorder severity, age gaps, and sex, which cause huge differences in the results if were not accounted for in the sampling process. Those factors should be accounted for when making a statement as well as when comparing results. Not taking them into consideration results in arbitrary not effective findings which delay the development of influential strategies to diagnose Autism Spectrum Disorder, as well as delaying the process of explaining strategies to parents and therapists to interact with people experiencing Autism Spectrum Disorder.

 

References:

Centers for Disease Control and Prevention. (2018) Autism and Developmental Disabilities Monitoring (ADDM) Network. Retrieved from https://www.cdc.gov/ncbddd/autism/addm.htm

Kenward, B. (2012). Over-imitating preschoolers believe unnecessary actions are normative and enforce their performance by a third party. Journal of experimental child psychology, 112(2), 195-207.

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders. Arlington: American Psychiatric Publishing.

Gallese, V., Fadiga, L., Fogassi, L., & Rizzolatti, G. (1996). Action recognition in the premotor cortex. Brain, 119(2), 593-609.

Iacoboni, M., Woods, R. P., Brass, M., Bekkering, H., Mazziotta, J. C., & Rizzolatti, G. (1999). Cortical mechanisms of human imitation. science, 286(5449), 2526-2528.

Martineau, J., Andersson, F., Barthélémy, C., Cottier, J. P., & Destrieux, C. (2010). Atypical activation of the mirror neuron system during perception of hand motion in autism. Brain research, 1320, 168-175.

Fishman, I., Keown, C. L., Lincoln, A. J., Pineda, J. A., & Müller, R. A. (2014). Atypical cross talk between mentalizing and mirror neuron networks in autism spectrum disorder. JAMA psychiatry, 71(7), 751-760.

Raymaekers, R., Wiersema, J. R., & Roeyers, H. (2009). EEG study of the mirror neuron system in children with high functioning autism. Brain research, 1304, 113-121.

Fan, Y. T., Decety, J., Yang, C. Y., Liu, J. L., & Cheng, Y. (2010). Unbroken mirror neurons in autism spectrum disorders. Journal of Child Psychology and Psychiatry, 51(9), 981-988.

Puzzo, I., Cooper, N. R., Vetter, P., & Russo, R. (2010). EEG activation differences in the pre-motor cortex and supplementary motor area between normal individuals with high and low traits of autism. Brain research, 1342, 104-110.

Mandy, W., Chilvers, R., Chowdhury, U., Salter, G., Seigal, A., & Skuse, D. (2012). Sex differences in autism spectrum disorder: evidence from a large sample of children and adolescents. Journal of autism and developmental disorders, 42(7), 1304-1313.

Lai, M. C., Lombardo, M. V., Pasco, G., Ruigrok, A. N., Wheelwright, S. J., Sadek, S. A., … & MRC AIMS Consortium. (2011). A behavioral comparison of male and female adults with high functioning autism spectrum conditions. PloS one, 6(6), e20835.

Oberman, L. M., Ramachandran, V. S., & Pineda, J. A. (2008). Modulation of mu suppression in children with autism spectrum disorders in response to familiar or unfamiliar stimuli: the mirror neuron hypothesis. Neuropsychologia, 46(5), 1558-1565.