The Neurobiology of Autism

Most people who know me know that I love working with people with special needs. I have always had a specific interest in autism spectrum disorders (ASD), since so much about it is still unknown. As I’ve been working toward my certification in neurofeedback, I’ve been learning more about the brain and how it functions. I wanted to share some things that I learned about which brain abnormalities are present in ASD. For those who may not be as familiar with the diagnosis, ASD is typically described as lack of normative social and emotional skills, issues with executive function, and deficits in language and communication.

First, I have learned that there is evidence that the skulls of people with autism are larger than average. Recent studies show that the enlarged heads correlate with larger brains. The white matter (neural connections) of the brain is increased, contributing to the increase in the size of the brain. The white matter is shown to be increased in all lobes, but with a majority in the frontal lobe. The frontal lobe is where social and emotional skills and executive function stem from.  Evidence also supports that ASD is a disorder rooted in the dysfunction of neurons and their projections. In other words, there are more neurons than average, but they don’t communicate properly.

I’ve also learned that there are abnormalities in minicolumns, which are neural structures used in information processing. Evidence shows that there are more minicolumns, but they have smaller cell bodies and nucleoli, and are narrower. Due to the smaller size of the minicolumns, there is less space taken up by GABA (a neurotransmitter that inhibits excitability throughout the nervous system). It is hypothesized that this deficit in cortical inhibition is the related to the sensory sensitivities experienced by those with autism.

The last piece of information I’ve learned is that there is abnormal function of mirror neurons. A mirror neuron is what fires when a person acts and when a person observes the same action performed by another. For example, when a mom smiles at her baby, the mom’s mirror neuron is firing, and the baby’s mirror neuron is also firing by observing mom smiling. The abnormal function of mirror neurons in ASD correlate with the deficits in social and emotional skills. In the study I read, no mirror neurons were activated during observation and imitation of emotional facial expressions.

Keep in mind that Autism Spectrum Disorder is just that- a spectrum. This means that these brain abnormalities are not going to be present in all people with autism, and the severity of the abnormalities are going to be different as well. There is much more research that needs to be done to gain a better understanding of autism and the brain. However, the information I have learned so far has been very helpful in increasing my understanding of autism, so I am able to provide the best care for the people that I work with.

Written by: Olivia Clark, MA, LPC