There are two facts that you need to know in order to understand just what dyslexia is and what it is not.
1. Dyslexia is not a defined disease, illness or malady but a unique collection of symptoms. Unique, because no two sufferers will have exactly the same symptoms or underlying causative factors.
2. Every person with “dyslexia” will have their own presentation of the dis-ease based on co-morbidity factors. Therefore, someone primarily labelled as “dyslexic” will have aspects of other developmental problems with a unique presentation for that individual.
To read case studies detailing dyslexia click here
These other developmental problems include Dyspraxia, Attention Deficit Disorder (ADD), Attention Deficit Hyperactivity Disorder (ADHD), Tic disorders and Obsessive Compulsive Disorder (OCD). What this means is that a child primarily diagnosed as being “dyslexic” may well be 40% dyslexic, 15% dyspraxic, 30% ADD, 10% ADHD and 5% OCD.
We can therefore now view dyslexia as a unique collection of learning difficulties which are specific to the individual and in itself due to varying degrees of immaturity or under functioning of specific areas of the nervous system.
Recent research would suggest that more than 30% of children diagnosed as suffering from dyslexia may in fact have convergence insufficiency – an inability to bring the eyes in towards the nose – a condition that can be diagnosed in minutes and effectively treated in weeks. See the Meridian video on the research page.
So where are these areas of the nervous system and how do they produce the learning difficulties so commonly seen? A big clue came from NASA when they discovered to their cost that highly intelligent astronauts suddenly became “dyslexic” when subjected to the weightlessness of space travel. When big companies have paid big dollars to have complex experiments carried out in conditions of weightlessness, the last thing you want is to have the experiments carried out by a severe “dyslexic”. NASA had to find an answer and find it fast.
The solution to the problem was in itself both simple and effective. The astronauts were given specific exercises to perform on a regular basis that would afferentate (send messages along specific nerves into the central nervous system) the vestibular system (balance centres) and thereby the cerebellum. The cerebellum is the little brain that occupies the back of the skull and which up to recently had received very little attention.
It is now known that the cerebellum works in partnership with certain brainstem nuclei and is critical in the timing of movements. Now you may think that this has nothing to do with “thought” but you would be wrong. The “Theory of the Discontinuous Nature of Movement” states simply that the motor systems of the body are turned on and off at a regular 8-12 Hz. This timing, plus the notion that “thought” is at its most basic level the internalisation of movement, itself relies upon the thalamus (nuclei at the base of the brain) oscillating at a steady 40 Hz.
The cerebellum also has to work very specifically with the cerebral hemisphere on the opposite side of the brain. If either partner in this arrangement is working below par it will bring down the level of functioning of its co-worker. This situation, where one part of the brain affects a remote yet functionally related area is called diaschisis. This is a truly chicken and egg situation.
However, although the cerebellum does play a role in the generation of learning/behavioural issues, it is not the prime cause and we must look to the cerebral hemispheres themselves to find the primary locations.
The prefrontal lobes (the very front part of the brain) naturally go through a process of maturation which is why small children do not have bladder control and are also emotionally incontinent with tantrums bursting forth following the most trivial of stimuli. The prefrontal cortex and in particular the medial (inside) wall of the right hemisphere is the home to some little known neurons which are essential to our development as fully functional humans. For further information see the section below on von Economo neurons (VENs), gigantopyramidal cells and Calcium Binding Calretinin cells.
The prefrontal lobes are an integral part of what is called the neo-cortex (new brain) and function in subduing the older more primitive brain which is primarily concerned with surviving and breeding. They also provide the concept of time, error correction, the ability to concentrate, humour, etc. etc.
The orbital frontal area (above the eyes) functions in what might be termed “the social graces “. That is, fitting into the behavioural confines of a modern society and controlling the more primitive urges we all possess within a time frame to when it is more appropriate or suppressing them completely if such behaviour would breach the laws of society.
The insular – a tiny area to the back of the orbitofrontal area – is divided into 3 primary areas and ultimately provides us with what we are at any given moment of time. You reading this word is the ultimate function of the insular.
The dorso-lateral area (side) is one of the areas of the prefrontal cortex that has to develop to provide what has been termed executive function. An example of this would be delayed gratification. We have all experienced the situation when a small child wants something and they want it “now”. No matter what you say or how you try to explain the situation there is going to be tears if gratification is not immediate.
The anterior cingulate gyrus is thought to be essential to the ability to 1) keep still, 2) concentrate and 3) have error correction. As with the areas of the prefrontal cortex mentioned above they contain von Economo neurons (VENs). Only 15% of these cells are present at birth, the remaining 85% develop and migrate to these sites in a window which has been called Bpoptosis occurring between 4 months and 4 years after birth.
It has been suggested that this postnatal development may make these essential neurons vulnerable to stressors including maternal stress, foetal distress, birth interventions, food additives and the environment.
So is there a reason why some children develop dyslexic traits and others do not? Research has shown that there is a genetic link. If on the mothers side there is a history of any of the developmental disorders then one or more of the off-spring have a 37% chance of manifesting dyslexic traits. And now for the bad news, if the history on the fathers side on the family the likelihood of the dyslexic trait rockets up to 70%.
Before blaming yourself, remember you didn’t order the genes and it is only a trait. In order for the gene to become active something else has to trigger it off, e.g. foetal distress, trauma or dietary factors. It is the old story of nurture and nature interacting. Fortunately, it is not all bad news as we now know that in the majority of situations DNA is no longer destiny. What this means is that our genes and whether or not they express themselves is down to the Epigenome.
The Epigenome can be thought of as a series of switches which potentially can switch on or off the genes they control. A great many of our genes are concerned with our development – morphogenesis – not only while we are in the womb but also as we continue to grow and develop. It is suggested that stressors may prevent development, while a good diet and a stress free passage through early life may help the brain to develop and mature.
The “typical” child with dyslexia will be a boy with an under active left cerebellum, a right prefrontal diaschisis, a left eye that cannot converge accurately or hold that convergence and a right eye that fails to constrict and hold that constriction when directly illuminated.
Put into plain English this means that dyslexia is a variety of learning difficulties which are simply the manifestations of problems with the maturation and functioning of areas of the central nervous system.
Now that we have a better understanding of what causes dyslexia, is there anything that can be done to help? Fortunately, there are a few people working in the field of functional neurology who have set up specialist clinics designed to tackle the problems of the “Developmental Delay Syndromes”. The first and most critical aspect of the treatment regime is to identify the specific areas of the nervous system that are under functioning and then, and only then, targeting the treatments to the sites that are struggling to keep up with the rest of this most complex system.
The treatments per se will be directed to the malfunctions identified during the thorough neurological examination. The eye that fails to follow an object that is brought close to the nose will be treated by a computer generated programme that itself can be adjusted to address the specific unique needs of the child. A random dot stereogram (3D picture) will gradually exercise the neural control centres and muscles involved in convergence (bringing the eyes towards the mid-line) and bring both eyes to focus on the page as well as keeping them in sync as they track across the page.
The vestibular (balance) system can be challenged by simple physical exercises which can then be refined to specifically afferentate specific areas of weakness. The timing nuclei of the brainstem can be re-set by the use of an ingenious computer generated treatment regime that encourages the child to re-educate and thereby restore the temporal sequencing of events within the motor systems and thereby the brain by attempting to anticipate the precise timing of a metronome.
As these individual areas are treated the effects of the diaschisis must also be addressed and this requires both an awareness of the sites that are compromised, based on the history and examination, but also an in depth knowledge of the functions of these areas and precisely how they can be effectively treated. Failure to address the phenomenon of diaschisis inevitably leads to failure, the loss of vital time (the younger the child the easier it is to treat) and often an unhealthy bank balance.
Can all children be accepted for this type of therapy? The answer is unfortunately no. Children who are truly autistic are not currently accepted for treatment as they require one-to-one treatment on a daily basis for long periods of time. Also, at the initial assessment a parent or the parents are also interviewed to rule out lack of parental control and to ensure parental compliance during the course of treatment. Put simply, if the parents fail the interview the child is not accepted and alternative measures directed at improving parenting skills are suggested.
This initial meeting lasts about 1.5 hours.
Little known neurons
Von Economo Neurons (VENs)
Von Economo Neurons (VENs) were described in detail by von Economo in 1925. They then disappeared into obscurity until Esther Nimchinsky et al described them again in 1995 at which time they were known as spindle cells. Since that time a number of papers have been published on the limited number of species that have them – great apes, certain whales and dolphins, elephants and humans – their structure and their possible functions.
VENs have been implicated as having a possible role in a number of neuropsychiatric / neurodevelopmental disorders including learning and behavioural issues in children. For further information see the Research page or books by Robin Pauc.
In 1976 H Braak described a field of gigantopyramidal cells (big motor neurons) in the mid cingulate gyrus (middle section of the inside wall of the brain) which had not previously been known of. Imaging studies have shown that this mid-cingulate area becomes active when the subject performs a precision grip opposing the thumb and index finger but also when the subject imagines such an activity. For years it had been thought that in a right-handed individual the right arm and hand were controlled by the left side of the brain but now following the work of Braak and others we know that the right arm is controlled by the left side of the brain but the right hand is also controlled by the right side of the brain.
It has been suggested that if these cells are late to develop, the child will employ a fist-grip when writing as the motor areas of the brain that are functioning correctly employ a power-grip as opposed to the precision grip necessary for fine motor control.
Calcium Binding Calretinin cells
In 2001 Hof et al described a previously unknown group of pyramidal (motor) neurons restricted to the anterior cingulate cortex of humans. The precise function of these cells is not known but it has been suggested that they may play an important role in the control of the autonomic nervous system (controlling digestion, heart rate and the fight-or-flight response, etc.) and/or be projection neurons to motor centres involved in the production of facial expression and vocalisation. It has been suggested that immaturity of the anterior cingulate gyrus or unparalleled development with other areas of the brain might provide the underlying cause of certain tic disorders.
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