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Disabilities and abilities: A neurological Cause
By Marja Blom

People who educate our children are supposed to be objective. That is sometimes difficult. People base their beliefs on what they know or what they expect to be there. Because certain problems among children are not generally understood, some children suffer more than they should. These are the children with neurological deficiencies.

People studying developmental psychology encounter case studies about a boy who is well co-ordinated, intelligent and socially competent. When explaining his success according to the theories of developmental psychology we could attribute his success to factors such as parenting style, social class,temperament and genes. But even if a child is intelligent and all the factors in the environment are positive it is rare for a child to excel in all areas. This is because none of us have perfect sensory integration.

Piaget’s theory of cognitive development explains that in the first two years a child develops by adapting his responses to the sensations he experiences. In this sensory motor stage the child is integrating sensations. The integration starts before birth. The construction and organisation of the sensory information system takes until about year seven. By this time most interconnections between the neurons in the brain have been made. Our higher functions, like academic skills are based upon the system of sensory integration. Without sensory integration higher functions are not possible.

When sensory integration is successful at about seven the mature brain will show lateralisation. Different parts of the brain become specialised in different functions. For example in the left hemisphere, which directs the right hand, a part becomes specialised in handling tools. Children with bad sensory integration don’t have a preferred site for handling tools. Both sides of the brain direct this function but neither side becomes good at it. When complex functions have to be established the two sides of the brain have to work perfectly together. This is the case with language, speech and spatial ability.

The brain receives information which comes from the receptors. Receptors are the receiving organs of the sensory input. They sent a wave of energy through our nervous system to the brain. In the brain this information about our environment and our body gets integrated and interpretated. The brain receives information from the following senses:

The vestibular system is our most basic and important sense. It is located in the inner ear and gives information about the pull of gravity. This is needed to help straighten our body and strengthen our muscles to resist the pull of gravity.
The proprioception or muscle and joint sensations tell us if our head is turned for example and to adjust our eye muscles when our head moves.
Through the tactile system or touch sensations we learn for example where our body begins and ends. It is also important for our emotional development.
The eyes are sensitive to sight and receive basic information about our environment.
Our ears receive sound waves. A lot of integration with other senses is necessary to make sense out of sound.
Visceral input gives information about internal organs and the blood.

The average brain consists of 12 billion neurons. These neurons consist of a celbody and twigs. These twigs are connected to other neurons. The neurons receive electrical impulses sent from our different receptors. In the brainstem all this information comes together. They meet each other in the rectular formation in the brainstem. This is a netlike centre of neurons. Here the basic information gets integrated and a rough perception gets sent to the higher parts of the brain. In the cerebral hemisphere more information is added and the message gets more refined and accurate.

Let us look at a few examples how this sensory integration works. At a certain point a child achieves object permanency. The child is now able to understand that an object continues to exist even if he can’t see it. This is because the child can symbolise the object. This means he has a perception of it in its mind. For example to get the whole picture of an orange we need our eyes to give us information about the colour and the shape. The brain integrates this with the touch sensations of the fingers and the smell sensations of the nose.

Another example is when the child learns to bike: When he bikes he must sense the pull of gravity and the movement of his body. “When he moves off the centre and begins to fall his brain integrates the sensations of falling and it forms an adaptive response.” He must now balance his body and he sent information to his muscles and joints. If he integrated the information well he made the right response. This response is than stored in the neural memory. This will be used next time he rides a bike.

The brain has a neural memory of every movement the body made. It has a body perception. The brain knows exactly what the body can do and where all his body parts are. A child with bad sensory integration doesn’t have a good body perception. He doesn’t know what his body can do and where all his body parts are. Without a good body perception the child doesn’t have a good sense of self. This makes him very insecure and this result in bad self-esteem. When you ask a child with a bad body perception to close his eyes and to identify the finger you touch, he is not able to. Therefore when he has to do handwriting he has to press very hard to “feel” what he is doing.

There are a lot of things in the neurological system that can go wrong and often it isn’t know where it goes wrong. There might be a traffic jam of the neurological information stream in the brain. Sometimes only one kind of sensory information doesn’t come through or is too slow which might be caused by a deficiency of specific neurotransmitters. The problem however is that every person is affected in a different way.

When the dysfunction is severe and when it affects a specific learning area, we know the dysfunction as a specific learning disability. It is called specific to differentiate it from general learning disabilities like mental retardation. It is a disability because it affects the child for his whole life. Some of these learning disabilities are dyslexia, ADHD and dyspraxia.

A factor which often causes dyslexia is that the child has a problem with a part of auditory perception. This part is called phonological awareness. In this case the child is unable to distinguish between the different sounds of a word. When he has to read a word he is therefore also unable to blend these sounds together.

When the vestibular input isn’t right the child can’t keep his eyes and head steady. This can cause dyslexia as well. There can also be deficiencies in the memory system. When decoding the last part of a word some children already forgot about the first part. In this case there is a problem with the active working memory.

When a child can’t modulate all the sensory input he gets a sensory overload. He becomes hyperactive when trying to react to all the different input at the same time.Girls often react to sensory overload by slowing down. That a person can’t focus his attention is often caused by a dysfunction in the vestibular formation. This part of the brain is responsible for the organisation of the cerebral hemispheres.

When a child is unable to plan his actions and when his muscles don’t get the right information than the child can have dyspraxia. This can happen for example because of bad sensory input of the vestibular system or bad sensory input of the muscles and joints. Because this affects the foundation of sensory integration, higher functions in the brain also show deficiencies. It is for example not unusual that dyspraxic children are dyslexic as well.

I have only show a fraction of what sensory integration is and what sensory integrative dysfunction can mean for a child. Sensory information gives us the building blocks for coordination, emotion and academic learning. It is therefore very important for our development. It is like the hardware in a computer. Even when you have the best software, without good hardware a computer doesn’t work properly.

The working of the brain is very complex. It takes some time to understand it. When we learn to understand the brain we know more about how people learn. We also learn why some people have troubles with reading, writing and coordination. People can adjust their expectations and give the right help. When children with sensory integrative dysfunction don’t get the right help they will eventually drop out of school and maybe even end up in crime when they are very frustrated.

We also learn to understand that everybody has some disabilities. Some people can practise endlessly to learn a musical instrument without mastering it. We don’t say however that he has a music disability. Music isn’t important in our education. Reading is however needed to access the curriculum. A person with a reading disability can however be very strong at music. If somebody plays an instrument perfectly and has a good verbal ability he could excel in life. But this depends on him being resistant enough and not losing his self-esteem when going through our education system with a severe reading disability.

In conclusion we need to understand how our brain works to understand why some children have problems and how to help them. To do this we have to increase our awareness and our knowledge. Neuroscience should therefore be a part of the study of child development. The more we understand the brain the more we understand people.

Note: The theory about sensory integration in this article is based on the book Sensory Integration and the Child, by Jean Ayres, Ph.D. 2000, 14th printing. Meanwhile the tactile system plays an increasingly important role in the system of sensory integration. This article is however pure to give lay people an idea of what sensory integration is all about.

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