Tuesday, 26 October 2010

Treating the Sensory Distortions of Autism

What do we mean when we say autism is a 'spectrum disorder?'

When the term, 'spectrum disorder' is used it means that there are a range of symptoms, which can be attributed to autism. Any one individual may display any combination of these symptoms, in differing degrees of severity. Therefore an individual at one end of the autistic spectrum may seem very different to an individual at the other end of the spectrum.


Who first discovered autism?

Autism was first recognised in the mid 1940’s by a psychiatrist called Leo Kanner. He described a group of children, whom he was treating, who presented with some very unusual symptoms such as; - atypical social development, irregular development of communication and language, and recurring / repetitive and obsessional behaviour with aversion to novelty and refusal to accept change. His first thoughts were that they were suffering some sort of childhood psychiatric disorder.

At around the same time that Kanner was grappling with the problems of these children, a German scientist, Hans Asperger was caring for a group of children whose behaviour also seemed irregular. Asperger suggested that these children were suffering from what he termed ‘autistic psychopathy.’ These children experienced remarkably similar symptoms to the children described by Kanner, with a single exception. – Their language development was normal! There is still an ongoing debate as to whether autism and Asperger’s syndrome are separable conditions, or whether Asperger’s syndrome is merely a mild form of autism.




What is the cause of autism?

In the 1960s and 1970s there arose a theory that autism was caused by abnormal family relationships. This led on to the ‘refrigerator mother’theory, which claimed that autism in the child was caused by cold, emotionless mothers! (Bettleheim, 1967). However the weight of evidence quickly put this theory to bed as evidence was found to support the idea that the real cause was to be found in abnormalities in the brain. This evidence was quickly followed by findings, which clearly demonstrated that the EEG's of children with autism were, in many cases, atypical and the fact that a large proportion of children also suffered from epilepsy. Recent findings also point to various neurological abnormailities, the most common finding seeming to be that the brains of children with autism have an abnormal wiring pattern, - a pattern of connectivity between brain cells which is not present in non - autistic individuals.

So, autism is now looked upon as a disorder, which develops as a consequence of abnormal brain development. Recently, evidence has shown that in some cases, the abnormal brain development may be caused by specific genes.

However, we should not forget that genes can only express themselves if the appropriate environmental conditions exist for them to do so and so, we should not rule out additional, environmental causes for autism. We should not forget that autism can also be caused by brain-injury, that an insult to the brain can produce the same effects as can abnormal development of the brain which may have been caused by genetic and other environmental factors. I have seen too many children who have suffered oxygen starvation at birth, who have gone on to display symptoms of autism. So, it is my view that autism can also be caused by brain-injury.

There are also other possibilities, which can ultimately produce the type of brain dysfunction, which we recognise as autism. There is a great deal of research being carried out at the moment in the area of 'oxidative stress' and 'methylation' and it's effects upon the integrity of neural networks. There is also the debate surrounding mercury levels in vaccines, which is as of yet, unresolved.

The fact is that 'many roads lead to Rome.' - There are likely to be several factors both genetic and environmental, which can ultimately lead to the type of brain abnormality, which we call autism.




So, how do we recognise autism?

On a descriptive level, autism involves a dysfunction of the brain's systems, which control communication, socialisation, imagination and sensory perception. My theory is that it is the distortions of sensory perception, which are so characteristic of autism, which exacerbates many (but not all) of the other difficulties. Imagine a child suffering from autism who suffers distortions of sensory perception. For instance, the child who suffers distortions of visual perception, might find situations which require eye -contact to be exceptionally threatening, or on the other end of the scale might become obsessive about specific visual stimuli. The child who suffers distortions of tactile perception, might at one end of the spectrum find any situation which requires physical contact to be terrifying, whilst at the other end of the spectrum, they might be a 'sensation seeker' to the point of becoming self -injurious. The child who suffers distortions of auditory perception might at one end of the spectrum, be terrified of sounds of a certain pitch or intensity, whereas at the other end of the spectrum, they might actively seek out, or become obsessive about certain sounds.





Treatment

The question is, what can we do to help redress these distortions of sensory perception. Well, we believe we can learn from the newborn baby. When baby is born, he sleeps for most of the time, only spending short periods of time interacting with this new environment in which he finds himself; - a new environment which bombards his senses with new sights, noises and smells. So he retreats into the safe, calm environment of sleep, which provides the sensory safe haven which up until recently was the sanctuary of the womb. Very gradually, as baby adjusts his sensory system to his new environment, he spends more and more time in the waking world, interacting and learning to communicate, - but he adjusts very gradually!

There is possibly a neurological explanation for this. There are structures within the brain, which act to 'tune' sensory attention. These three structures, which allow us to tune our attention are structures, which enables us to ‘tune out’ background interference when we wish to selectively attend to something in particular. They also enables us to ‘tune in’ to another stimulus when we are attending to something completely different. They are the same mechanisms of the brain, which allows us to listen to what our friend is saying to us, even when we are standing in the midst of heavy traffic on a busy road. It is these mechanisms that allow us, even though we are in conversation in a crowded room, to hear our name being spoken by someone else across that room. It is these mechanisms, which allow a mother to sleep though various loud, night-time noises such as her husband snoring, or an aeroplane passing overhead and yet the instant her new baby stirs, she is woken. It is a remarkable feature of the human brain and it is the responsibility of three structures operating cooperatively; - these are theascending reticular activating formation, the thalamus and the limbic system.

Having made such a bold claim, allow me to furnish you with the evidence to support it. The three structures just mentioned receive sensory information from the sense organs and relay the information to specific areas of the cortex. The thalamus in particular is responsible for controlling the general excitability of the cortex (whether that excitability tunes the cortex up to be overexcited, tunes it down to be under excited, or tunes it inwardly to selectively attend to it’s own internal sensory world.) (Carlson, 2007). The performance of these neurological structures, or in the case of our children, their distorted performance seems to be at the root of the sensory problems faced not only by newborn babies, but the sensory difficulties our children face and yes, as the newborn shows, their performance CAN be influenced, - they can be re-tuned.

I believe the sensory system of some children with autism is experiencing similar difficulties to that of a newborn, - at one end of the autistic spectrum, the cortex is being over-excited by these structures and the person is overwhelmed and has difficulty accommodating the mass of sensory stimulation within the environment. At the other end of the autistic spectrum, the cortex is being under-excited and the person has trouble in perceiving sensory stimulation from the environment. The question is; - How do we facilitate the re-tuning of this neurological system in individuals who have autism

The newborn retreats into sleep, a self imposed dampening of incoming sensory information. Whilst the child with autism does not do this, many children with autism attempt to withdraw from their environment because they find it so threatening.

We believe at Snowdrop that for the child at the end of the autistic spectrum who is suffering an amplification of sensory stimulation, we should create a setting where he can retreat from a world, which is overwhelming his immature sensory system. This 'adapted environment,' which should be as free as possible from all visual, auditory, tactile and olfactory stimulation will serve as a milieu where his sensory system can re-tune itself. Of course it may just be a single sense like vision, or hearing, or tactility, or any combination of senses, which are causing the difficulties and the environment may be adapted appropriately. The child suffering these difficulties will usually welcome this adapted environment, which is in effect a 'safe haven' for his immature sensory system. He should be given free access to, or placed within the adapted environment as needed and you will notice hopefully that he will relax and begin to enjoy being within its safe confines, where there are no sensory surprises.

This procedure should be continued for as long as necessary, - for several weeks or months. Indeed, some children might always need periods of time within the 'safe haven.' As the child begins to accept and be at ease in his safe haven, stimulation in whatever sensory modality is causing the difficulties, should begin to be introduced at a very low level, so low in fact that it is hardly noticeable. If the child tolerates this, then it can be used more frequently until it becomes an accepted part of the sensory environment. If the child reacts negatively in any way, then the stimulus is withdrawn and reintroduced at a later date. In this way, we can very gradually begin to build the level of tolerance, which the child has towards the stimulus.

For the child at the other end of the autistic spectrum, the child whose sensory attentional system is not exciting the cortex enough, with the consequence that he is not noticing enough of the stimulation in his sensory environment, the approach needs to be the exact opposite. These are the children who we see producing self-stimulatory behaviour. I believe that this behaviour is an attempt by the nervous system to provide itself with what it needs from the environment, - a sensory message of greater intensity! We see many children with autism 'flapping' their hands in front of their eyes, or becoming visually obsessed by certain toys, movements, colours etc. I propose that this is a reaction by the nervous system to attempt to increase the intensity, frequency and duration of the sensory stimulus due to a problem with perceiving visual stimuli from the environment.

Of course, children with autism display a far greater range of difficulties than a theory, focused upon a malfunctioning sensory – attentional system could explain. I am not attempting to claim that sensory problems on their own are an adequate explanation for every facet of autism, - that would be ridiculous! This is merely a possible explanation of a range of issues experienced by some children who have autism, which could be produced or exacerbated by the child suffering distortions of sensory perception. For instance, the following symptoms within the autistic spectrum could possibly be explained at the sensory level.
  • Failure to make eye contact.
  • Difficulty in sharing attention with anyone.
  • Avoiding interaction with others
  • Avoiding physical contact
  • Seeming disconnected from the environment.
  • Appearing not to notice anything visually.
  • Visual distraction, as though the child is looking at something which you cannot see.
  • Visual obsession with particular features of the environment.
  • Inability to 'switch' visual attention from one feature of the environment to another.
  • General discomfort with the visual environment.
  • Appearing not to hear anything.
  • Auditory distraction, as though listening to something which you cannot hear.
  • Auditory obsession with particular sounds within the environment.
  • Inability to 'switch' auditory attention from one sound within the environment to another.
  • Inability to 'tune out' extraneous sounds in the environment.
  • General discomfort with the auditory environment.
  • Appearing not to feel much sensation.
  • Appearing to bee distracted by tactile stimuli of which you are not aware.
  • Obsession with particular tactile sensations within the environment.
  • Appears unable to 'switch' tactile attention from one sensation to another.
  • General discomfort with the tactile environment.
  • Difficulty in communicating with others.
We believe at Snowdrop, that our sensory re-tuning environments offer the best chance for children to overcome such distortions of sensory perception. For more information contact us at info@snowdrop.cc or read our book 'Autism. - A Guide to Understanding and Helping Your Child.

Monday, 25 October 2010

Spastic Cerebral Palsy.

This is the most common form of cerebral palsy, comprising almost 80% of cases of CP.  Children who have this have tight muscle groups which limit movement.  Essentially, ‘spastic’ merely means ‘stiff,’ which makes it a good, descriptive word.  However in more recent times the word has taken on an emotive slant and has been used as a term of abuse, which is unjustified and unacceptable.

Spasticity is caused by injury to the cerebral cortex, or the cortico-spinal, or cortico-thalamic nerve fibres  and is easily distinguishable from stiffness of the muscles caused by injury to other areas of the brain because of the ‘clasp knife’ effect.  When you push against a stiff muscle which is produced by midbrain, or basal ganglia injury for instance, there is total resistance to the force you are applying and the affected limb will be difficult to bend.  However, when we push against a muscle which has spasticity, we meet initial resistance, but then the affected limb suddenly ‘gives’ and the limb bends.

Normally, muscles work in pairs. When one group contracts the other group relaxes, allowing free movement in the desired direction. Due to complications in brain-to-nerve-to-muscle communication, the normal ebb and flow of muscle tension is disrupted. Muscles affected by spastic cerebral palsy become active together and block effective movement. This causes the muscles in spastic cerebral palsy patients to be constantly tense.

There is also a range of severity within the condition, as with all neurological problems.  Children who have spastic cerebral palsy may have only mild cases that affect only a few movements, or severe cases that can affect the whole body.   Although spastic cerebral palsy is not  a progressive disorder, as brain damage does not get worse over time, spasticity in muscles can increase over time. This increased muscle tone and stiffness in spastic cerebral palsy can limit the range of movement in the joints. The effects of spastic cerebral palsy may increase with anxiety or exerted effort, leading to excessive fatigue.

This type of cerebral palsy also negatively affects a child’s joints, and can cause contractures, dislocations and deformities  and can disrupt normal growth in children. Spastic cerebral palsy can inhibit several things such as normal motions in body movement, longitudinal muscle growth, and protein synthesis in muscle cells.

What can be done to treat spasticity?

There is no quick fix unfortunately and no guaranteed cure, but Snowdrop have developed programmes of developmental stimulation which are designed to influence brain function and neuroplasticity, so that the pattern of neural activity which is producing the spasticity is overlaid with a pattern of activity which encourages normal neuromuscular control.  This takes time, patience and work.

If you would like more information about Snowdrop programmes of developmental stimulation simply email snowdrop_cdc@btinternet.com or visit our website at http://www.snowdropcerebralpalsyandautism.com

Tuesday, 12 October 2010

Athetoid Cerebral Palsy.

What is ‘Athetosis.’
Athetoid cerebral palsy, which is also often referred to as dyskinetic cerebral palsy is, like the other two major types of cerebral palsy, (spastic and ataxic ), a type of brain injury.  It typically involves injury to a structure just below the cerebral cortex, called the basal ganglia.   Approximately 10% of children with cerebral palsy have this type.
Children with athetosis experience variations in muscle tone, where sometimes it can be too high and other times it can be too low.  When the muscle tone is too low, children can have immense difficulty in maintaining posture for sitting and walking.  This mixed muscle tone also causes difficulties with hand function and the child might experience great difficulty in holding onto a pen, pencil or eating utensil, or indeed in completing any movement which requires smooth coordination.
Athetosis is characterised by the involuntary, purposeless movements which it causes, especially in the arms, trunk and face.  These movements become worse when the child is under stress, but in most cases, disappear completely when the child is asleep.  The unwanted movements caused by athetosis might be small or big, rapid, irregularly repetitive, random or jerky.
The basal ganglia also acts as a 'braking system' for movement, which enables us for instance, to sit still. In order to sit still a 'brake' has to be placed on all other movements. Consequently injury at this level hampers the 'braking system' and we see children who cannot sit still and are in constant movement (athetosis, or athetoid cerebral palsy, or Parkinson's disease or Huntingdon's Chorea). Injury to this part of the brain also exhibits itself in many children, by retention of the primitive postural reflexes, as it is the role of the basal ganglia to suppress these in order to enable the child to move.
The basal ganglia also plays a role in cognitive processes, emotional processes and our ability to learn. It also provides inhibition to the thalamus, a part of the brain which mediates our sensory experiences. So, without this inhibitory role, one can imagine a thalamus in effect operating without its 'braking system' which might produce many of the sensory distortions we see in children who have brain injuries.
Where can we get treatment?
Snowdrop provides treatment programmes for children who have all types of cerebral palsy, including athetoid cerebral palsy.  Anyone wanting more information should email snowdrop_cdc@btinternet.com or visit the Snowdrop website.

Saturday, 9 October 2010

Autism Vs Sensory Processing Disorder.

This is a variant on a question I am frequently asked.


Question.  I am going to have my 6 year old son tested for Autism and Sensory Processing Disorder. His teachers thought that would be a good idea. What i'm concerned about, is the fact that a lot of doctors won't acknowledge that SPD is different from Autism and treat it. They treat SPD as autism and thus the treatments don't work. Of course, this is all what I have discovered, and not experienced first hand. My question I guess, would be how do they know the difference in Autism and SPD since they have such similar signs? Also, if he has SPD and is treated for Autism, or visa versa will the treatments still work since they are different. Does anyone have any insight on this subject? Thanks in advance!




Answer. - Hi. You are quite correct to distinguish the fact that it is possible to have SPD whilst not having autism. I see many children who have 'stand alone' SPD, also children who have dyspraxia and cerebral palsy who also have SPD. I also agree with you that it is very important to treat the SPD as an individual problem, - but I believe this to be the case whether it is found alone, in Autism or in CP or dyspraxia.

The brain operates on a series of sensory - motor loops, for instance if we have distorted visual perception, - because language, hand function, socialisation and motor systems are dependent upon good visual development for their own good development, - we can expect to see these systems suffer.

If we have distorted auditory perception then we will see the dependent 'output systems,' of language and social development being adversely affected. - These are primary systems which are affected in autism, so you can see why so many professionals automatically link the SPD with autism.

If we have distorted tactile development, then the dependent motor systems of mobility, hand function and socialisation will be affected, so we again see the connection with autism.

What I am clumsily trying to say, is that the pattern of brain injury which causes SPD, displays itself many times in output terms in what we like to call 'autism.' 

Now for treatment. Personally, I don't go along with the treatment methods employed by the establishment at all. They are usually symptom oriented and I prefer to address treatment to the cause, - the injured brain which is producing SPD, or what I prefer to term 'distortions of sensory processing.' These distortions are produced primarily by the malfunctioning of two systems within the brain. The first is the 'Ascending Reticular Activating System,' which is partly responsible for directing our attention towards incoming stimuli from the environment. Second is the Thalamus, which has been shown to be a relay station for sensory information, directing it to the appropriate part of the cortex for further processing. The thalamus also 'excites' the appropriate region of cortex, to enable it to process and analyse that information.

So what goes wrong? When these two structures malfunction, it results in either the attentional systems not being directed to pay attention to incoming stimuli, - so we see a child who simply does not seem to perceive the outside world sufficiently in terms of vision, hearing, or touch. We can also see a situation where a child's attention is mis-directed so that he pays too much attention to a particular stimuli. As I said, the thalamus is also responsible for exciting the cortex and it can under-excite it, or over-excite it. This results in either undersensitivity in a sensory modality or oversensitivity.

The good news is that these two structures can be re-tuned by the provision of an appropriately adapted sensory environment. In this way the brain can be taught to modulate incoming sensory stimulation at a more natural level.

This is only a brief description of some of the many distortions of sensory processing which can occur, in order to give you an example. Hope this helps.

If you need more information, visit the Snowdrop website, or contact me at snowdrop_cdc@btinternet.com

Thursday, 7 October 2010

Question about Dysgraphia?

This is a question I was asked a few weeks back.

 

Question

Ok so I have Dysgraphia and I was wondering if it goes away when your older? I have to take notes in school and I want to I just don't think I can stick with it. Writing just takes allot of focus and it makes me tired and eventually I get distracted. I don't know if i'm being silly or whatever and dont want to take notes? Is there something I can use to take notes? I don't like the idea of a tape recorder cuz you cant get to where you want to immediately, like you can if its right there on paper...
Answer.
Hi. I also have dysgraphia so I identify very strongly with what you say. I am 48 and it hasn't gone away! Strangely I'm ok on a keyboard, - that seems to 'gel' nicely, but when I start to try to write things down, it's just a mass of confusion. You seem ok on a keyboard too, which is often the case with people who have dysgraphia. Have you considered asking if you can take a small notebook, or laptop computer into class with you, so you could take notes on that? Alternatively, if your school understand your problems, couldn't your teachers produce 'handouts' of their lessons, listing the major points, which you could add to later?
 


Dysgraphia is produced by 'phonological processing problems' and whilst I have learned to live with it and find ways around it, what I usually do with children who have dysgraphia is to introduce a programme of 'phonological awareness.'  (A phoneme is an individual speech sound belonging to a particular language, - there are 43 of them in the English language).  This seems to improve the difficulties the child is experiencing

Anyone wanting more information on dysgraphia, or on Snowdrop programmes should visit the Snowdrop website.
or email snowdrop_cdc@btinternet.com

Hope this helps.

Wednesday, 6 October 2010

Question. - Why is my almost 4 year old not talking yet?

I get asked many questions by parents.  It is part of the service we provide to try to provide answers to those questions.  I thought I would write a series of posts containing the more interesting of those questions, so that other people who are experiencing similar difficulties can refer to them.

This is a question I was asked by a mother this morning.  -

Question

" Why is my almost 4 year old not talking yet? He makes allot of sounds and trys to say some words, but for the most part he does not any true words.  He has been in speech therapy for almost a year but has not showed much improvement.  He is a very happy and smart child.  He just want talk.  I am beginning to think something medical may be the cause.  He has seen doctors and has passed hearing screenings.  I was wondering if there are any other medical reason that impairs speech."

Answer. -


What you need is to be able to place this problem in the context of a global developmental assessment. Only then will you truly be able to ascertain if there is a problem and what might be causing it. There are many reasons for lack of language development and impaired hearing is only one of these, so the fact that he has passed hearing tests, merely eliminates one factor.  For instance, there are several vital precursor stages to language development, which you would not think were even connected to it and if he has missed one or more of these stages, well then the stage could very well be set for language and communication problems.

For example, some children do not develop the ability to make eye - contact or become attracted to looking at faces. Some children for various reasons do not develop a good level of phonological awareness (a grasp of the sound system of spoken language). There are many more reasons why a child might have difficulties.
 

If you are worried and you clearly are I would suggest you consult the Snowdrop website and book an initial consultation so that we can begin to identify what is causing this problem and how we might successfully address it.


Hope this helps..

Potty Training.

One of the most frequent questions which arises and it arises with both brain injured children and uninjured children concerns potty training.  Parents drive themselves to distraction over this issue, to the extent where potty training is one of the major factors in child homicide in the Western world.  So, how can we defuse this situation?


 It has estimated that the average child goes through 6,000 nappy, (diaper) changes before he finally progresses  to sole use of the potty or toilet.  For most overstressed, frustrated parents, that's a few thousand too many.  The frustration many parents experience when attempting to inspire their child's switch from nappy to potty or toilet can be similar to the stress levels they may face at work, moving house, or when a loved one is ill. 

Here are some valuable guidelines and ideas to deliberate over. -
Many parents connect potty training to house training a puppy and expect many trials and slips before finally succeeding.  What certainly doesn’t help is to give the child the impression that there is any pressure or disapproval.  We have to remember that there are a whole sequence of events, which have to occur before a child is ready and no amount of pressure, persuasion, or coercion will bring that day a moment closer.
Many so called experts promote strategies which essentially convey to the child that toilet training is something you do TO him.   This should not be the case, he should gain the impression that toilet training is a learning process and is something you do WITH him, together.  Some parents rush headlong  into the potty training arena and are then upset and worried because things don't go as planned.   This should be done at the right time, for the right reasons.
Many parents try to accelerate the process because many nurseries and child minders  won't accept -- or charge more for -- children in nappies.  When this is the motivation for getting a youngster out of nappies, the attempt is usually doomed to failure and a lot of confused tears -- and that’s just the parents’ reaction!  We have to understand that asking a child to do something for which he is not physically or developmentally ready can cause him to feel inadequate if as he sees it, he fails to live up to a parent's expectations, and that's  a great deal of stress for any little one to have to deal with.
So what do we do, I hear you ask.  My belief is that we should let the child lead the way, - it is the surest way to success.
Toddlers are not known for their level of cooperation.  Also, in many cases, their minds might be willing to move on to the concept of “bathroom skills,” but their bodies are not.  Until about 18 months of age, a child's neuromuscular development is still too immature to master “command performance” toileting.  Excretory functions up to this point are controlled by an automatic mechanism.
While each child is different, it is almost certainly a safe bet that by age two and a half, toilet teaching can efficiently begin.  There will be some indicators along the way:  a child may wake up dry from a nap, and stay dry for longer periods of time.  He may pause during playtime -- or even look surprised -- when urinating.  He may grumble about being wet or dirty and indicate by gestures or words that it is time to change him.  It is not far from this conscious awareness, to appreciating that he will feel better dry and clean by using the potty or toilet instead of his nappy.  For some children, this discovery combined with the encouragement to do something else just "like the grown-ups" sets them firmly on the road to making the transition.

Once your child seems to be physically and emotionally ready to begin toilet training, be sure your toddler can follow simple directions; walk to the bathroom without assistance; pull trousers, shorts and underpants down and back up without aid and understand what the potty or toilet is for.
What to do next.
Decide whether you will purchase a potty, or if you will teach them to use the toilet from the start.  I personally prefer those special little seats you fit onto a normal toilet.  I think getting them to use the toilet from the start saves parents going through the entire process again when the child transitions from potty to toilet.
What we now need to do is to break things down into a simple sequence, which can be taught a step at a time.  One of the first milestones in toilet training is getting your youngster to tell you when he has to go.  This is the first thing we focus on.  Don’t worry about getting him to the toilet at this stage, just focus upon developing the communication.  Remember to heap lavish verbal praise on him when he tells you, because what the brain does when it receives praise is to produce a neurotransmitter called dopamine.  Dopamine is very important in brain plasticity and learning and ensures that new connections between brain cells are formed to support the function from which the dopamine was produced; - in this case, communicating toilet needs.
The next stage to add on, when your child is successfully and regularly communicating their toilet needs is getting the child to hold it until you can get him to the toilet.  Tell him to wait, - that we only do toilet things in the bathroom.  There are bound to be mishaps on the way and don’t show disappointment when a mistake is made, just shrug it off and say, “oh well, - next time” and give him a hug.  When he does make it to the bathroom before relieving himself this should again be met with praise.
The next step is to get him used to sitting bare bottomed on the potty or toilet when he doesn’t want to go, just to get him used to it.  Talk about it whilst you are doing this and say that this is where everyone goes wee – wee or pooh!  Sometimes it helps if you add a little ‘auto-suggestion.’  Run the water in the sink while he is sitting there, and perhaps he'll feel the need to urinate, turning a practice run into a direct hit!  When this happens, celebrate it like he has just scored the winning goal of a world cup final, - get that dopamine moving!
Don’t forget to take away the fear factor too.  Many children are frightened of the toilet.  They don’t like the noise it makes, they don’t like the look of it, they don’t like the accoustices of the bathroom.  Show them how the entire thing works, how the toilet lid goes up and down and how the handles makes the water flush the contents of the bowl away.  Explain from the start, however, that the toilet is not a plaything and that one of the most important bathroom "rules" is to wash your hands after going potty.
Most of all, remember the three ‘Ps’ – Patience, patience and patience. Remember, when he's out with his mates at 18 years of age, he won't be in nappies then! - The situation will resolve itself ultimately.