In January Developing Intelligence ran an interesting study on how your pupils contract and dilate based on the amount of mental effort being used. Now they cover more research on how your blink rate correlates to dopamine levels.
However, a far more interesting determinant of spontaneous eye blink rate appears to be levels of cortical dopamine. If dopamine receptor 1 activity is enhanced (with D1 agonists), eye blink rate increases, and if it is blocked, eye blink rate decreases. Likewise, monkeys treated with MPTP (known to cause Parkinsonian type symptoms, a disorder associated with decreased dopaminergic activity) show reductions in eye blink rate, which is remediated by administration of D1 agonists (as are the Parkinsonian symptoms). This relationship is also robust in human populations, where people with schizophrenia show elevated blink rates and those with Parkinson’s show the opposite trend. Some research implicates the rostral ventromedial caudate nucleus in the dopaminergic modulation of eye blink rate; however, eye blink rate may be modulated only by D1 and not D2 activity.
See also: The Eyes Have It
Over the last few weeks this website has been attracting comments from various members and ex-members of staff of the Dore Achievement Centres. This has come to the attention of the CEO of UK branch, Bob Clarke, who has posted comments on Myomancy and also to Wynford Dore himself who has phoned me. Conversations with Wynford are always enjoyable but challenging because Wynford believes so passionately about what he does. So when Myomancy runs a negative story about the Dore Program he tends to forget all the places on Myomancy where I’ve said the Dore Program works and that it changes lives.
In light of all this I thought it wise to make a clear statement to all my readers about why I devote a considerable amount of time and money to running Myomancy.
- The goal of Myomancy is to provide independent information on treatments for dyslexia, ADHD and autism so that parents and sufferers can make an informed choice about what is the best approach for them.
- Myomancy is a blog, a personal web site. It represents my views and my views alone on all things connected with ADHD, dyslexia and Autism.
- These views are researched and expressed on Myomancy to the best of my abilities but I am not a scientist, teacher or a professional writer. I am just someone who’s life was changed by the Dore Program and felt a need to express myself.
- I believe in free speech which is why I allow anyone to post comments on the articles regardless of whether they are for or against my views. Only post that are illegal or purely offensive are removed.
- Myomancy generates a small amount of income for advertising. I would like it to be more so that I can afford to spend more time on Myomancy. It is up to the reader to decide what, if any, impact that has on the independence of Myomancy.
With reference to the above I have removed one comment from the website that is highly critical of the Dore Program and, based on additional evidence I have at my disposal, is completely false.
Nearly half of elementary school teachers surveyed about bullying in schools, admitted to bullying students, according to a study in the May issue of The International Journal of Social Psychiatry. The study surveyed 116 teachers from seven elementary schools. While more than 70 percent of teachers believed that bullying was isolated, an estimated 45 percent of teachers admitted to bullying a student themselves.
When I read this, my first question was ‘What do they mean by bullying?’. If you are being bullied by another kid, they steal your lunch money and stick your head down the toilet but what does a bullying teacher do?
Study Abstract: Teachers Who Bully Students: A Hidden Trauma
Does having dyslexia cause certain personality traits such as anxiety? This 2001 BDA conference paper thinks so:
…dyslexic people were the most likely to have been treated as less capable than was actually the case. One likely hypothesis is that these subjects therefore were at greater risk of feeling frustrated, believing that they were being unfairly treated and experiencing a degree of intellectual boredom. This latter arises where an individual is provided with a level of academic stimulation that is appropriate to the perceived level of ability, but is in fact at a more simplistic level than is actually required. Such a situation is likely to increase the high level of stress frequently produced by dyslexia. This can be sufficient to engender behaviour which is not only extravagant, but also out of context.
Personality measurement is always a slightly dubious area of psychology as they are based on self-reports. When self-reporting, how do we now that what I call highly stressed is what you call highly stressed? That said, the results are interesting the differences between the gender are notable.
The pattern of personality in dyslexic children and adults: the invisible symptoms and the effects they produce
Following a comment on the article Does Light Therapy Work? Some Real Evidence At Last I wanted to look into what effect the flickering of a TV screen has on the brain. As someone who watches too much TV and sits in front of computer monitor all day it is an issue close to my heart.
A TV screen refreshes the picture at 60 times a second (60hz) in the US and 50 times a second (50hz) in Europe. This refreshing happens to fast to consciously see but does it still have an effect?
The first information I found was related to photosensitive epilepsy, i.e. convulsions trigger by flickering lights. According to Professor Harding almost 50% of photosensitive epilepsy patients are sensitive to the european flicker rate where as on 15% are sensitive to the US rate.
Next is Entrainment to Video Displays in Primary Visual Cortex of Macaque and Humans [ PDF ]. This study found that cells in the V1 area of visual cortex did become entrained. Entrainment was greater when the display included strongly contrasted patterns.
This led me to a study on The effects of flicker on eye movement control. This wasn’t using a TV or monitor screen but involved reading printed matter whilst a light flickered at 50hz, 100hz or under a study light.
The results are consistent with the view that flicker has two distinct effects on reading, both of which are potentially disruptive. The first relates to an increase in the number of prematurely triggered saccades, which are, as a result, less accurate. The second is an increase in the number of saccades perturbed in flight, which land short of their intended target.
It is interesting to note that fluorescent lights flicker at 100hz or 120hz depending whether you are in Europe or the US. This suggests that reading under fluorescent lights is harder than reading under steady light. The author of the study, Alan Kennedy, did a second study examining eye movements (Eye Movement Control During the Inspection of Words Under Conditions of Pulsating Illumination), this time reading from a screen flickering at between 50hz and 125hz. This found similar evidence of an effect.
None of this gives a clear message on television flicker and the brain but it does tell us that flicker too fast to be consciously detected does have some effects.
In the nine years from 1993 to 2002, the number of prescriptions to children for anti-psychotic drugs increased from 210,000 to 1,224,000. Most of these 2nd generation drugs have not been approved for use on children are being used not to treat psychosis but for disruptive behavior disorders (37.8%), mood disorders (31.8%) and pervasive developmental disorders or mental retardation (17.3%). Only 14.2% were for psychotic disorders.
Medical professionals often criticise non-drug based, alternative treatments for their lack of scientific evidence and overreaching claims. Yet here are the same doctors prescribing unproved drugs to children for problems they were never designed to treat. Is it any wonder that parents are losing their faith in scientists, panicking at scare stories like MMR & Autism and turning to treatments of dubious benefit and safety such as chelation.
Abstract: National Trends in the Outpatient Treatment of Children and Adolescents With Antipsychotic Drugs
See Also: More antipsychotics being prescribed for children
Light therapy for ADHD, dyslexia and autism is a contentious area. How could spending twenty minutes sitting in front of a flashing light help children learn to read or control themselves? I was highly skeptical until I tried it myself (see Light Therapy Follow Up). Even having tried it I could only speculate on why it had the effect it did. Now some researchers have shown that light can effect your memory.
By exposing participants to a flashing light for one second, researchers in Oxford found that participants were better able to recall a list of trigrams (semi-random groups of three letters). Most importantly the improvements only happened when the lights were flashed at frequencies on or around 10.2 Hz. A frequency related to the brain’s alpha waves and believed to be relevant to memory functions.
Alpha waves normally span the 8 to 12 Hz range but this study was looking at older people with a mean age of 78. As the brain gets older its brain waves shift slightly and 10.2 Hz is the peak frequency for those aged 80 or above. The researchers tested flicker frequencies of 9.0 Hz, 9.5 Hz, 10.0 Hz, 10.2 Hz, 10.5 Hz, 11.0 Hz, 11.5 Hz and 500 Hz. Only those frequencies in the 9.5 – 10.5 Hz range improved participants recall.
This well designed study shows a clear link between flickering visual stimulus (sometimes called photic driving) and memory performance with strong evidence that the mechanism relates to brain wave activity. However this was a test of short exposure to flicker very quickly followed by the memory test. It provides no evidence as to what happens if the exposure to the flicker is longer or to how long the effects last. Both of these points are vital to understand what, if any, effect light therapy can have on people with learning disorders
Here we move into the field of speculation. It is clear that brain wave patterns do relate to cognitive abilities and behaviour. It also changes as we age, notably during childhood. Is it possible that children with learning problems that are related to poor short-term memory are stuck with the alpha wave patterns of a young child? If this is the case, could repeated exposure to photic driving train the brain to have strong, more consistent alpha waves? It is possible but much more research is needed.
10 Hz flicker improves recognition memory in older people [ PDF ]. Originally spotted on the excellent Developing Intelligence who have their own informative write-up.
Developing Intelligence has a great post on why we may be missing the point of Mirror Neurons.
A recent review paper by Adele Diamond suggests that research on mirror neurons and research on the developmental time course of abstract thinking may be ‘missing the forest for the trees.’ In other words, the important feature of premotor and iVLPFC is not that they contain mirror neurons, or that fMRI shows them to be active during generalization tasks. Instead, the important feature of this region is that it is fundamentally responsible for associating things that are not physically connected.
Conceptual Thinking: Just Out of Touch
Inspired by this letter I’ve been researching links between methylphenidate (Ritalin) and cocaine addiction.
First I dug out the study mentioned in the letter. ‘A choice procedure for drug reinforcers: cocaine and methylphenidate in the rhesus monkey‘ used Rhesus Monkeys to examine if, when given a choice, the monkeys preferred cocaine, methylphenidate or saline solution. The monkeys ignored the saline solution but showed no preference between cocaine and methylphenidate. One interpretation of this data is that both cocaine and methylphenidate offer the same rewards to the user.
In the 2003 study ‘Adolescent Exposure to Methylphenidate Alters the Activity of Rat Midbrain Dopamine Neurons’ [ PDF ] they found that rats given low doses of methylphenidate where more likely to self-administer cocaine as adults.
In another 2003 study, ‘Methylphenidate and MDMA adolescent exposure in mice: Long-lasting consequences on cocaine-induced reward and psychomotor stimulation in adulthood‘, mice where found to be more susceptible to cocaine and to be more likely to relapse in to drug use if they had been given Methylphenidate.
Its not all bad news for Ritalin. In a detail analysis of how cocaine and methylphenidate effect the brain, ‘Is methylphenidate like cocaine? Studies on their pharmacokinetics and distribution in the human brain‘, the study concluded that Ritalin and cocaine were very similar but were as cocaine drops out of the body quickly, Ritalin remains. This is good news because it is believed that it is the high followed by a rapid decline that makes cocaine so addictive. Where as in Ritalin, the high is followed by a slow clearance making the effect less pronounced.
It is clear that there is some risk that children given methylphenidate in adolescence will be more likely to abuse cocaine in later life. However this leaves parents in a difficult situation. Untreated children are more likely fail in school leading to poor work prospects in adults and low income is a major risk factor in lots of diseases including drink and alcohol addition. A real catch-22 situation.
Whilst trying to track down the source of this article on how 7 million Americans have abused ADHD drugs I came across a study about treating cocaine users who have ADHD. There is some evidence linking cocaine use to ADHD but that wasn’t the focus of the research.
98 adults who were receiving treatment for cocaine use and had been diagnosed as having adult ADHD where enrolled on a 12 twelve treatment program for their ADHD. Split into three groups, they were treated either with sustained-release methylphenidate, sustained-release bupropion or a placebo. After 12 weeks of treatment the participants where reassessed on the adult ADHD rating scale and the result were startling. All three treatments worked about the same. Yes all three, including the placebo, a fake drug that does nothing, led to a notable reduction in symptoms.
Whilst the study group of cocaine using adults is not a the mainstream population of adult ADHD sufferers it does demonstrate the striking impact of the placebo effect and how one’s self-belief can dramatically effect behaviour.
Treatment of methadone-maintained patients with adult ADHD: Double-blind comparison of methylphenidate, bupropion and placebo