How differences in brain wiring affect motor control and learning
It is now generally accepted that atypical development of connectivity between different brain regions underpins the sensory, motor, and communication difficulties experienced by individuals on the autistic spectrum.
The main finding is that local connectivity between adjacent areas of the brain is usually greater than in neurotypical individuals, but that connectivity between distant brain regions is underdeveloped.
Recent research into the possible causes of atypical development of brain connectivity has started to look closely at how differences in sensorimotor abilities, present from early infancy, may provide clues to the many difficulties experienced by autistic children. It is argued that basic sensorimotor abilities developed in the first year are the building blocks for later skilled motor actions and social communication.
How experience builds a library of internal models
Infants learn motor skills through experience. They are motivated to explore and try out new things. They try out different ways to achieve their goals. They persist until they succeed.
Each new experience contributes to a grwoing library of internal models that link the intended action to the sensory consequences. This experience is vital for developing connectivity between different brain regions.
Research has shown that infants at risk for autism (who are later diagnosed as being on the autistic spectrum) engage in less exploration and trial and error learning. Over time their actions become stereotyped and repetitive and this means that they do not build the myriad internal models that connect sensory information to motor output.
The consequence is poorly developed sensorimotor control of the basic repertoire of movements that underpin more skilled action.
How motor control is affected in autism
Poor prediction and anticipation
Each time a new action is learned, the movement brain creates a set of internal models that link the sensory information associated with the action with the motor plan. These internal models allow the individual to use information from the body and the environment to predict what will happen next. The more experience you have in a particular situation, the better you are at reading the situation, predicting what to expect and adapting your behavior to respond in an appropriate manner.
Walking in a busy shopping mall
Walking in a busy shopping mall I keep an eye on the movements of the people up ahead, and based on previous experience, am able to predict the direction they are moving and plan my path accordingly.
If, however, the fire alarm goes off, and people all start to move rapidly towards the exits, their behavior becomes unpredictable and I need make moment-to-moment decisions about my direction so as not to bump into people who move across my path.
Autism affect building internal models
Children with autism are less good at forming the internal models needed for predicting what happens next. This means that even in familiar situations, the child has difficulty knowing what will happen next and needs to pay attention to and respond to events on a moment-to-moment basis.
Catching a ball is based on prediction
A child with autism may be quite good at ball throwing skills, but have difficulties with ball catching. This is because catching a ball depends on predicting the flight path of the call and moving the hands to the right place at the right time to intercept the ball.
Control of simple movements is affected
Reaching forwards to touch a circle on a card with the forefinger is a simple action. The hand moves from its original position to the new position, usually in a straight line. If the circle is 5 cm in diameter the movement will be faster than if the circle is only 1 cm in diameter.
Children with autism do not make the adjustment in the speed of the movement to a smaller circle - which affects the accuracy of the pointing action.
Timing of movements and force production may be variable.
Using sensory information for motor planning
Autistic children are good at detecting sensory signals from the muscles and joints as well as from the touch, visual and auditory sensors. In fact, research has shown that autistic children are often very good at discriminating small differences in touch and simple sounds.
However they have difficulty interpreting and integrating the information from the different senses and in using this information for motor planning.
They have particular difficulty with activities that involve visual information from the environment, especially information about moving people and objects. This is why autistic children have poor ball skills; they have difficulty predicting the path and speed of the ball as it moves towards them and planning which makes it difficult to plan the movements needed to bring the hands to the right place at the right time to catch the ball.
Poor automatization of motor control
An important aspect of learning a new task is the shift from needing to pay attention to what you are doing to the stage when performance of the task is fairly automatic and requires less attention. This is referred to as automatization.
- Repeated practice of a tasks needed for automatization to happen. Children with autism who avoid tasks that are difficult or challenging, do not get the practice needed to make everyday tasks less attention demanding and easier to perform.
Balance control and postural stabilization may be a problem
Every time we move the body makes subtle shifts in the alignment of the different part of the body to maintain balance. At the same time there are adjustments in muscle activity to keep the trunk and head steady.
- The responses needed to maintain balance and keep the head and trunk steady are specific to a task - that is why task based training is the best way to improve a child's balance.
Throwing a ball from above the head requires a complex set of adjustments to maintain balance as the ball is lifted above the head, and then to keep the trunk and head steady as the ball is thrown.
These adjustments are specific to the task, and can be improved with repeated practice of throwing a ball from above the head.
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Joan, mother of 8 year old autistic Zak and SfA Training Club member
Your website is the only site I have found that has answered all my questions and provided practical solutions for my son's challenges with posture, muscle strength, hand writing and muscle tone.