Critical Development Theory of Autism

We have come across a new neurological explanation of autism, which is actually able to explain the huge range of different presentations of autism. This theory is from Dr. Michael Merzenich. Dr. Michael Merzenich has been a leading pioneer in brain plasticity research and has applied his research in this area to create computer systems to help children and adults. His commercially available system, BrianHQ, is designed to prevent and improve cognitive decline due to aging.

When babies are born, their brains have very little structure. A lot of development needs to occur throughout childhood to create an adult brain. In early development, babies soak up stimuli and learning with ease. This is because there are critical periods of development where the brain just needs to be exposed to stimuli to learn. This stimulates the neurons to create brain maps for movement, different sounds, vision etc. Over time, the brain maps become more differentiated. So initially a movement may stimulate a large number of neurons, but as the movement, such as walking, becomes more established and efficient, fewer neurons fire for this activity.

Once these critical periods are over, it takes effort to learn. This is why children learn a second language in the same way that they learn their mother tongue if they are exposed to it before the critical period for language learning ends. After that time, it takes more effort to learn another language.

This theory suggests that in autism the critical periods get cut short, resulting in the brain not fully differentiating for different stimuli. If this affects sound processing, for example, then many neurons will fire for a particular sound rather than just a few, or even one. This explains difficulties with sound discrimination and also explains why too much sound stimulation creates overload. It may also explain why at least some autistic brains ‘light up’ more when doing tasks in scientific studies.

This is consistent with Olga Bogdashina’s sensory framework. A key part of this framework is gestalt processing when stimuli (such as a scene) are perceived as a whole and processing for separating everything out is fragmented or delayed. Olga Bogdashina explains that this is because there is insufficient filtering of irrelevant stimuli and the person is trying to process everything, which is impossible for anyone. Hyper-sensitivity, fragmented and/or delayed processing and overload are the result. This also means that if just a small part of the scene changes, it is noticed immediately because it no longer makes the same pattern as it did.

Re-phrased in this theory, this would become more neurons in the brain are activated in response to seeing a scene. This means that the scene is perceived as a whole pattern. If the scene is familiar, such as a room at home, then the person will immediately know if something is out of place. But what is not happening, or happening in a fragmented or delayed way, is identification of different objects in an unfamiliar place. So, for example, a person may not be able to carry out a request to open the window because he or she has not managed to identify the handles. The handles have remained as part of the background pattern.

In more efficient processing, less of the scene is processed and changes in areas that are not important are filtered out and not noticed. Instead only important changes are noticed, such as changes in position of the furniture or a new object on the floor.

Some people are more observant than others, meaning that they notice more changes and less is filtered out. Could this be as a result of a not fully differentiated visual map? That is, they retain some aspects of gestalt processing?

This shortening of the critical period of development can apply to any part of the brain. When it is cut off prematurely, it will create a milder or greater deficit. In addition, the more areas of the brain that are involved, the worse the symptoms of autism will be.

I suspect that we could add to this. In autism some parts of the brain have a longer period of critical development than would be expected. In some autistic people, learning seems to be less effortful for longer. The stereotypical autistic memory may be part of this.

However, I don’t think that this explains autism completely. For example, it does not explain Temple Grandin’s super-highway from her frontal cortex to her visual cortext that enables her to think in pictures, and create videos in her head. It appears that in autism, there is compensation for these less differentiated parts of the brain and sometimes this results in unusual skills that the autistic person does not want to lose. Some autistic people have very interesting and effective learning methodologies, for example.

This theory does show a lot of promise for helping autistic people and it has helped a lot of autistic people. The software Fast ForWord, also developed by Michael Merzenich’s team, has been shown to help children who are struggling at school. It can move them from being behind to being within the top 25% within a few months.

This theory explains why sound therapy methods such as Tomatis and Berard Auditory Integration Training do help. They help with sound discrimination and this in turn helps with language understanding. When applied to autistic people, because hearing and vision are linked, sound therapy has helped with vision processing, which in turn has helped with proprioception (sensing where the parts of the body are). The effects can be profound.

However, I would be hesitant to apply this kind of technique to all autistic people without a full understanding of what is going on with the autistic individual and how all the different facets are interacting. The last thing I would want is to improve functioning in one area but that then causes the whole edifice of compensation and alternative development to collapse. That would be incredibly distressing and disabling for the autistic person and there is no guarantee it could be put back. Instead, the person would have to work hard to rebuild functioning.

In addition, many autistic people have issues with food intolerance which affect brain functioning. Gut issues may mean that important nutrients are not being absorbed in sufficient quantities and supplementation may be helpful. Heavy metal poisoning is also known to cause brain functioning issues, as do certain infections. All these factors should ideally be dealt with first. Not dealing with them may reduce the effectiveness of brain plasticity therapies.

Autism can be incredibly complex.