Notes on Autism
Quantitative Electroencephalogram (QEEG) Findings & Neurofeedback Training
Lynda Thompson, Ph.D. & Michael Thompson, M.D.
ADD Centre, Biofeedback Institute of Toronto
In the recent research literature on autistic spectrum disorders, five areas of the brain are repeatedly found to differ when compared to people with normal development. Most of these areas are connected to what is called the mirror-neuron system. Mirror neurons are groups of neurons that fire when a person is watching and mentally mirroring the actions of another person. Young children learn to mirror and reflect the behaviour and feelings of others, starting with their mother. Think of how intently a baby watches its mother’s face. This mirroring system is crucial for the young child in order to understand the intentions and meanings of other people, as expressed through nonverbal communication. In children with autism, this mirror neuron system is not functioning normally (See “Broken Mirrors” in Scientific American, by V. S. Ramachandran & L. M. Oberman, 2006).
What is now of great interest is that the lack of normal functioning in these critical areas of the brain can be easily seen using a completely side-effect free and non-invasive procedure called an electroencephalogram or EEG. The child sits wearing a cap that has built-in sensors that pick up electrical activity from the brain and the EEG is recorded. Later it can be analyzed and one can see what differs in that child’s patterns in terms of over-activation (or lack of activation) at various sites on the scalp and it is also possible to see if communication between different areas of the cortex is disrupted (coherence between two sites that is either too high or two low).
Six main areas of dysfunction in Autism that can be seen using the EEG are: (1)Amygdala with connections to the Orbital and Medial Frontal areas of the brain, (2) the Fusiform gyrus,(3) Superior Temporal Gyrus with the auditory cortex in the Temporal lobe, (4) the anterior Insula and the Anterior Cingulate (both part of the limbic system (the emotional brain), (5) frontal and parietal-temporal Mirror Neuron areas, and (6) the prefrontal cortex .
What is of even more interest is that, once irregularities in functioning are identified, the child can do training using a brain-computer interface that seeks to normalize the brain wave patterns. The child watches a game-like display that only moves when they produce the correct patterns. With enough practice, the brain learns these healthy patterns and, as the new, more normal patterns become established the child’s behaviour also changes.
One of the pictures that can be generated from the EEG assessment is called a ‘brain map’ and it may look like the following. This was a nine-year-old boy diagnosed as autistic. His language development was at a three-year-old’s level and he made little eye contact. He would draw a stick figure if requested, but preferred to draw a repeating pattern he called a train.
Each of the circles (labeled 1 – 20 Hz) shows how much electrical activity there is at a particular frequency. (Hertz means cycles per second – the EEG is an alternating current made up of a mixture of various frequencies. The equipment used for analysis can separate out how much power there is in each frequency, or in a range of frequencies, such as 8 – 12 Hz, which is called alpha.) The red colour means a very high level of activity. It is in the right parietal area for the frequencies from 8 -12 Hz, and this area plays an important role in processing sensory information and reading social cues. This is an important mirror neuron area at the junction of the parietal and temporal lobes. Injury in this area from any cause, even a small bleed (stroke) as might occur in an adult, may result in the affected person having great difficulty understanding emotions and innuendo, such as the hidden meanings in the other person’s tone of voice or in their gestures. At 6 Hz on the left side there is a red spot in the centre between the two frontal lobes, a site called FZ. Using mathematical calculations to locate the source of this activity (a program called LORETA) this slow, 6 cycles per second activity was discovered to come from a very important area involved with emotional feelings called the anterior cingulate. Too much slow wave activity suggests underactivation and, in an autistic child, this parallels the symptom of not appropriately understanding or showing emotion.
In other brain maps that were done on this child other frequencies and sites showed up and some of these findings are discussed below. The next three pictures are LORETA images. They look like slices through the brain. It looks very like the pictures you might expect to see with and fMRI (functional magnetic resonance imagery) but these pictures are derived from a mathematical process developed in Switzerland by Roberto Pasqual-Marqui at the KEY Institute, Zurich, called Low Resolution Electromagnetic Tomography – LORETA for short. Each one shows the area that was the source of some of the abnormal activity seen on the surface of the cortex in various brain maps. The anterior cingulate gyrus is often involved when there are problems with emotional understanding and /or emotional regulation. (This not specific to autism but is also seen in other conditions such as anxiety disorders.) In the case shown below, the bright red colour indicates that this child has far too much fast wave activity (17 cycles per second) in this area.
The LORETA image below shows bright red at a very important ‘mirror neuron site in the left frontal lobe. This indicates the 20 cycle per second activity is far too high compared to the normal data base.
Parents of children with a diagnosis of autism have probably heard of the fusiform gyrus. It is an area of great importance in understanding facial expressions and it generally is not functioning normally in these children. The LORETA image below picks this up very clearly showing an abnormality at 18 Hz.
Recent literature has emphasized dysfunction in a small central nucleus of neurons called the amygdala. Dysfunction here can mean that the child cannot correctly interpret the emotions of other people and it may also mean that they cannot control their own emotional responses. They may ignore things or, on the other hand, they may over-react.
In the LORETA view below, the amygdale is shown to have far too much of a very slow wave called delta.
In the brain map shown below is a picture we frequently see. Here 7 cycles per second is far above the data base for normals. The area is nearer to the back of the brain in an important area for the synthesis and integration of all sensory (hearing and vision) information. (Normal would be a solid green colour rather like the colouring seen at 6, 8 and 9 Hz.) In this brain map, the red colour means that this child is more than 3 standard deviations outside the normal average (95 % of the children his age would have less 7 Hz activity at this ‘Pz’ site).
In each case shown above it is NOT the frequency (number of waves per second) of the wave that is most important. What is crucial is the area of the brain where the electrical activity differs from normal, the function of that area, and whether the functions of that area correspond to the difficulties that particular child is having.
Another critical factor is the way different areas of the brain communicate with each other and this is called ‘coherence’. In autistic children it can be too much or too little communication between areas, as compared to normal children of the same age and sex.
In the coherence patterns below (from the same nine-year-old boy whose brain map was shown first above) the red lines in the far left circle of the second diagram (after 40 sessions) show far too many sites near the back of the brain on the left side are doing the same kind of activity at the same time as areas in the frontal lobes (faulty parietal-frontal connections, especially in the left hemisphere, which handles most language functions). In the second circle from the right there is a light blue line between the left and the right hemispheres of the brain, meaning too little communication. Coherence is calculated for different frequency ranges. Again, a professional trained in EEG biofeedback can help the child to normalize this kind of brain activity using special computer games as feedback, through a learning process called neurofeedback.
Progress Testing after 40 sessions:
Work had been done mainly on beta and theta and he is now more focused and much less anxious.
Now training will focus on decreasing delta coherence in the left brain while also teaching language comprehension.
The second coherence diagram shown above was based on EEG measurements done after 40 sessions of training. Coherence is beginning to normalize in this nine-year-old boy. Childhood Autism Rating Scale (CARS) ratings done by parents have moved from the ‘severely autistic’ range into the ‘mild to moderately autistic’ range. He receives special direct instruction in academic areas and is now doing oral reading at a second grade level, up from a preprimer (Kindergarten) level. His training was twice a week for his first 40 sessions, and he now does training once a week and continues to improve.
Research on Autism is taking place on many fronts. The experience to date using neurofeedback is encouraging. The application of the findings of neuroscience research, including recent work on the mirror neuron system, is perhaps a most exciting front as it seems to empower the child to make changes in the way they pay attention and perceive the world, thus allowing them to get more from other behavioural and educational approaches. More research is needed since, to date, it is case outcomes that have been reported rather than controlled studies. Those case outcomes are promising. Training the brain – bringing inactive areas online and improving communication between different areas of the cortex using Neurofeedback - will likely become an important tool in the tool-kit of interventions for Autistic Spectrum Disorders.
Further information may be found in:
Lynda Thompson, Michael Thompson and Andrea Reid (2010), Functional Neuroanatomy and the Rationale for Using EEG Biofeedback for Clients with Asperger’s Syndrome. Applied Pyschophysiology and Biofeedback, Volume 35, Number 1, March 2010, pp 39-61