Autistic have changes in the amygdala

autism

Nerve bridge between you and me

In the human brain, too, researchers subsequently found mirror cells in all centers of the brain that control experience and behavior. Their central function seems to be to reflect what is going on in our fellow human beings. We share everything that our counterpart is doing by starting a simulation program in our own head.

Nerve cells in the brain could therefore be responsible for the fact that we intuitively anticipate actions even before they happen. The sight of someone else ramming a splinter under their fingernail makes us feel the pain too.

It is probably due to the mirror neurons that we imitate the behavior we see: whether as a baby the mother's smile, whether as an adult, mostly unconsciously, the facial features, moods and postures of our counterpart.

Mirror neurons in autism research

For a long time, scientists like Vilayanur Ramachandran saw mirror neurons as a key to many open questions in autism research. The researcher tried to explain why nothing moves inside a person with autism when, for example, he sees someone laughing. Is that perhaps because, Ramachandran concluded, that his brain does not reflect his fellow human beings?

To measure brain activity in people with autism, Ramachandran used electroencephalography (EEG). The EEG records the brain waves using external sensors. In his studies, the researcher paid special attention to the so-called "My waves" (pronounced mü, after the Greek letter µ), a special component of the EEG.

It has long been known that the My wave is suppressed every time a person performs a muscle movement - for example, opens and closes their hand. Interestingly, this component is also blocked when the person watches the other person doing the same thing.

Ramachandran found that in people with autism, the My wave is only suppressed when they are doing their own movement, but not when they are watching someone else do the movement. The researcher concluded that people with autism have defective mirror cells.

Faces as the key to understanding

Imaging methods initially supported the hypothesis. Magnetic resonance tomography, for example, uses electromagnetic fields to depict the condition of tissue and organs. This enables researchers to visualize which areas of our thinking organ are particularly active during a task.

For example, if we see a person, the "face recognition area" in the brain is activated. If, on the other hand, a person with autism looks at a face, this area remains silent.

Instead, another area switches on, which healthy people use for general object recognition. This would explain why many people with autism have difficulty interpreting and recognizing faces.

Overstimulation and extreme emotions

However, not all aspects of autism can be explained with the help of the mirror cells, such as the typical avoidance of eye contact, the stereotypical repetition of movements or a general hypersensitivity, especially to certain noises. A sophisticated filter system in the brain protects non-autistic people from overstimulation.

A kind of scale is stored in the nerve cells, which indicates which processes are dangerous and how a person reacts to them appropriately. At the sight of a threat, for example, the body is put on high alert: the heart beats faster, the muscles work harder, the skin sweats.

Autistic people often react to insignificant events or objects with extreme emotions. Researchers suspect that this is due to incorrect processing of sensory data in the brain, incorrect communication between nerve cells.

This would explain why people with autism avoid eye contact, insist on the same procedures, or perform stereotypical movements. You want to prevent emotional turmoil and calm yourself down.

Evaluation of brain research on autism

The developmental disorder autism is very complex and complex. In addition, patients often have very different brain regions affected. The researchers are therefore still a long way from an explanation.

The initial euphoria to be able to explain the autism spectrum disorders with the help of the mirror neurons has now disappeared. Over the years researchers have come up with conflicting results. Some studies have found that people with autism have healthy mirror neurons.

A 2018 study by an international team of researchers from Germany, France and Australia concluded that there is insufficient evidence to make mirror neurons the sole culprit for autism disorders.

According to the researchers, it is rather a whole network of nerve cells that are responsible for autism. The mirror neurons make up only one layer of many. A 2020 study by British researchers also supports this extended mirror neuron hypothesis.

But: Even if the new hypothesis explains the cause of autism, researchers do not yet know which risk factors lead to it.

Various studies suggest that autism is genetic. If the father or mother has an autism disorder, the probability is high that the child is also affected.However, different studies identify different sections of the genome as suspicious of autism - for example the absence or duplication of certain sections of the chromosomes.

A well-known and well-researched change is what is known as fragile X syndrome. A section of the X chromosome is changed. However, not all people with fragile X syndrome also have autism disorder. Researchers therefore suspect that only a complex interplay of genetic and environmental factors leads to autism. Which factors these are and how they are to be weighted still has to be deciphered.