Richard G. Petty, MD

Handedness and Immunity

In 1982, one of my mentors, the late Norman Geschwind, and two colleagues – Al Galaburda and Peter Behan – proposed an extraordinary hypothesis. It was that the levels of testosterone to which a baby is exposed before birth influence the development of both the cerebral and immune systems. According to this theory, high levels of testosterone result in greater incidences of left-handedness, deviations from the standard distribution of cerebral functions and increased autoimmune dysfunction. If the theory is right, then male brains should mature later than female brains, and the left hemisphere should mature later than the right.

It is certainly true that if a boy gets a head injury or infection involving the brain, he is less likely to recover than would a girl, and boys are far more likely to have some types of neurodevelopmental problems like dyslexia.

For a while it seemed as if there was also a strong association between left-handedness and certain types of allergy, and also with inflammatory bowel disease. This association with immunity also seemed to be present in mice: those who had left paw preference had more reactive immune systems, and they were thought to be more likely to produce auto-antibodies, suggesting that the central nervous system was involved in the genesis of some autoimmune diseases. Over the years the data has become less clear-cut, but the idea of an association between anomalous cerebral asymmetry and autoimmune disease never completely went away.

Recent data has again found an association between inflammatory bowel disease and laterality. And left-handers really do have more autoimmune disease.

The Geschwind-Galaburda hypothesis proposes that there should be a four-way association among neurodevelopmental disorders, special talents, non-right handedness, and immune disorders. In a huge study of 11,578 children, less than 1% had all four.

So where does this leave us?

The original theory was half right:

  1. There is indeed a link between testosterone and early brain development
  2. People who are left-handed or have a strong tendency toward left-handedness do seem to be at slightly increased risk of several autoimmune conditions
  3. People who are left-handed or have a strong tendency toward left-handedness may have a slightly increased risk of high blood pressure, asthma and migraine
  4. People who are left-handed or have mixed handedness are more likely to excel in certain disciplines: creative arts, music, computer programming and mathematics. What we don’t know is whether people with these special skills are more likely to have autoimmune diseases
  5. Amongst very successful tennis players,  there are far more left-handers than would be predicted by chance. This supports the idea that support the notion that left-handed people have neurological advantages in performing certain tasks, such as visuospatial visuomotor cognitive tasks.

I was reminded of the way in which Nature seems to like to balance things out a bit: with some notable and famous exceptions, many successful athletes have not done so well academically and many academics would be unlikely to survive on the plains of Africa. Only some of these differences can be explained in terms of early direction and encouragement in school or while growing up: it seems that most of us cannot hope to become the kind of superman that Nietzsche used to dream about.

Perhaps it’s a way of stopping us from getting too full of ourselves.

Attention Deficit Disorder and Brain Laterality

Here two topics that are very close to my heart: the puzzle of laterality and asymmetry and attention deficit disorder.

We live in an asymmetric Universe. Fundamental particles tend to rotate and wobble to the left rather than the right; most molecules show a lateral shift; and all the biologically active amino acids – the building blocks of proteins – are in the L-form. Meaning that in solution they bend light to the left. The R-forms, that bend light to the right, for the most part don’t work in biological systems. Some of the most extraordinary asymmetry is seen in the human brain. There’s a myth that about the hemispheres of the brain that I’ve talked about before, but bears repeating.

The idea that the left hemisphere of the brain is specialized for logic, analysis and language, while the right hemisphere is holistic, artistic and mystical has been circulating for over thirty years. It has even been suggested that the right hemisphere of the brain is the seat of intuition, which cannot be correct. It may be involved in instinct, but it is impossible to reduce a non-local psycho-spiritual experience to groups of brain cells. There may be correspondence – the right hemisphere becoming activated during intuition, but not causality: right hemisphere activation as the cause of intuition.

This notion of discrete functioning of the hemisphere has become so pervasive that it is commonplace to hear people describing themselves as being “right brained,” or accusing someone else of being “left brained.”

A simple concept that is also profoundly wrong. This is fine as a metaphor, but not as a fact. It is true that language is more highly represented in the left hemisphere of the brain in right-handed men. But language is bilaterally represented in women. Most men tend to use a small strip of the left hemisphere for language, women tend to use both hemispheres at once. There’s still a left-sided predominance, but it’s quite a different pattern from most men’s brain.

Boy’s brains mature more slowly than girls’ brains, and by adolescence are more lateralized than are the brains of girls and women. The truth is that we cannot neatly divide up the functions of our brains, and we need both sides of our brain if we are to function at our best.

Until very recently most experts said that handedness was a purely human attribute. Yet anyone who has every lived with a cat, dog or horse knows that that is wrong, and now there’s literature to prove it.

I tried to put that mistake to bed in a review article that included a detailed discussion about brain asymmetries in animals. I also reviewed the excellent evidence that certain regions of the brain have been becoming more lateralized over the last 100,000 years.

I’d like to show you why this talk of brain lateralization is not a sterile academic debate.

We do not know if left-handedness or mixed handedness is more common in ADD/ADHD. But the evidence is getting stronger and stronger that there is something different in people with ADD/ADHD in how they use the two sides of their brains.

Three conditions: autism, dyslexia and ADD/ADHD share one characteristic: they are all marked by what we call atypical cerebral asymmetry in that they don’t have the normal left hemisphere dominance for language. This is more of a problem for boy, since they normally make more use of their left hemispheres. But it’s not all bad: atypical cerebral asymmetry may also be associated with certain aspects of creativity.

Researchers in New Zealand have just reported something strange, but which is consistent with previous research. When healthy right-handed children are asked to bisect a line drawn on a page, when they use their right hand they tend to bisect the line toward the right, and with the left hand toward the left. But children with ADD/ADHD don’t do this. The researchers have now gone further and suggested that there are at least two types of ADD/ADHD, in one of which – ADHD-I – the primary problem is in the right hemisphere of the brain.

Using an entirely different methodology, researchers in Baltimore, Maryland, have found that children with ADHD use their brains differently when engaged in patterned motor activity.

In an earlier post I talked about the dorsolateral prefrontal cortex, and there is an important connection to it is called the cingulate cortex. A new study has shown that adults with ADD had significantly smaller overall amounts of cortical gray matter, and reduced volumes of their prefrontal and anterior cingulate regions. Both are highly lateralized in the human brain.

Compared with controls, unmedicated children with ADHD have a small right cingulate cortex, but it is normal in children who have been treated, indicating that the treatment is doing more than treating symptoms: it may actually be re-wiring the brain.

Research from the UCLA Neuropsychiatric Institute and David Geffen School of Medicine showed that in adults with ADHD, showed reduced left hemisphere specialization, were better at processing emotions, and worse at processing words compared to controls. They tend to use their right hemispheres more and their left hemispheres less.

Unaffected individuals constantly shift their attention toward the important or salient things in their environment. Children with ADHD have a problem with directed attention: the ability to allocate and direct attention toward a salient stimulus. New research has discovered that this is due to problems in a region of the brain called the parietal lobe that is known to play a significant role in shifting attention and detecting specific or salient targets in the environment. As a result the child’s brain does not know what is important.

These findings do not tell us whether the primary problem is a way in which specific parts of the brain talk to each other, or whether the scientists are actually measuring the way in which the brain reacts to deficits in one region. Perhaps other regions take over the functions of parts that are not working as they should.

The most important take home message is that we already have methods for stimulating and integrating the hemispheres of the brain. Few have so far been much used in ADD, but this information gives us a whole new way forward.

Child Prodigies

I’ve recently had cause to look at the published literature on child prodigies and there’s not much there. It is very surprising that such an interesting subject has been so little researched.

First a definition from a paper by David Feldman: A “prodigy was a child (typically younger than 10 years old) who is performing at the level of a highly trained adult in a very demanding field of endeavor.” There are three fields in which high-level creative results have been produced before the age of 10: Chess, Mathematics and Music. There are other fields such as art and writing in which young people may be precocious imitators. Pablo Picasso exactly mimicked his father’s drawings. There is an impressive list of child prodigies in other fields as well, but it seems that only in chess, mathematics and music have profound, original insights been contributed by preadolescent children.

There is an interesting association between mathematics and chess: many top chess players are also extremely good at mathematics. In a previous post I mentioned the English Grandmaster John Nunn, and there are many other examples. Men dominate both fields, but that does not necessarily mean that there is a natural gender difference. There’s a very interesting book entitled Breaking Through, by the chess Grandmaster Susan Polgar who was herself a prodigy, as were both of her sisters. Girls have been excluded from many of these events, or they’ve been forced to play only against girls or women. I know a young person who as a pre-teenager wanted to join the school chess club, but only went once, after discovering that all the other members were boys. A shame: she was already quite a strong player.

Both chess and mathematics involve highly developed non-verbal and visuospatial skills. The writer and critic George Steiner had this to say: “The solution of a mathematical problem, the resolution of a musical discord or conclusion of a contrapuntal development, the generation of a winning chess position can be envisaged as spatial regroupings, that have their own internal logic.” He went on to speculate, “All three fields involve enormously powerful but narrowly specialized areas of the cortex. These areas can somehow be triggered into life in a very young child and can develop in isolation form the rest of his psyche. Sexually and socially unformed, very possibly backward in every general respect, the child virtuoso or pre-teenage chess master draws on formidable but wholly localized synapses in the brain.”

In the book The Exceptional Brain, Lee Cranberg and Marty Albert suggested that these “localized synapses” lie in the right hemisphere of the brain, which is primarily involved in non-verbal visuospatial skills and pattern recognition. They also suggested that gender differences in proficiency in chess support the right hemisphere idea. But after reading Susan Polgar’s book, and spending a great deal of time analyzing the world literature on gender differences in cognition, that last point doesn’t convince me.

It is striking that three of the code breakers at Bletchley Park during the second World War, were outstanding international chess players Stuart Milner-Barry, Harry Golombek and Hugh Alexander. These code breakers who helped win the War also utilized similar skills to those needed to master a chess position or to calculate a mathematical problem.

The child prodigies seem to have some things in common:

  1. An unusually strong talent in a single area
  2. Reasonably high but not necessarily exceptionally high IQ: some people with astronomically high levels of intelligence have had problems with interpersonal adjustment, unless very carefully nurtured as children.
  3. Focused energy.
  4. Sustained effort to achieve the highest levels in their field: even chess prodigies need thousands of hours of practice, and mathematical prodigies need to work at their field.
  5. Unusual self-confidence.

Adults who want to improve in chess are constantly told to practice as much as possible, and to work on pattern recognition and problem solving. It is just the same in music and mathematics.

Although child prodigies may simply have better neurological equipment, usually coupled with extraordinary encouragement by their parents, I am left with a question that I posed in an earlier post. Mozart often said that when he was composing he felt as if he was taking dictation from God. That he was not the one composing, but that he was in effect picking something up from the Universe. I’ve seen countless highly gifted people tell me that their greatest insights in science, music philosophy or chess just “came to them.” The former chess World Champion Tigran Petrosian once said that he could tell when he was out of form when his calculations did not confirm the validity of his first impressions. All this implies unconscious processing to be sure, but I am not sure that it is all in the brain.

Because there is another phenomenon that has also not been much researched, and that is the phenomenon of simultaneous breakthroughs: two or more people in different parts of the world coming up with new creative solutions at the same time and without any personal contact. I shall have more to say about this in another post, but it speaks to the fundamental interconnectedness of all of us.

Maybe the child prodigies not only have special brains and special parents, but they also have access to a store of information not available to everyone.

At least not yet: We already have training methods that help people access accurate information that they did not know consciously. A story for another day.

“Genius is characterized just by the fact that it escapes classification.”
–Leopold Infeld (Polish Physicist, 1898-1968)

Memory and Anticipation

“Nothing is so wretched or foolish as to anticipate misfortunes. What madness is it to be expecting evil before it comes.”
–Lucius Annaeus Seneca (a.k.a. Seneca the Younger, Spanish-born Roman Philosopher and Statesman, c.4 B.C.E.-A.D. 65)

We are all aware that memories of powerful and in particular disturbing emotional events – such as an act of violence or the unexpected death of a loved one – are more vivid and deeply imprinted in the brain than mundane recollections of everyday matters. When I was sixteen years old I was in a head-on car crash: I can still recall the number of the license plates of the car that was driving down the wrong side of the road as it barreled into us. But particularly positive emotions are also remembered in far more vivid detail, and those memories are less likely to be lost. This all makes good sense from an evolutionary perspective: we need to be able to remember things that carry a strong emotional charge.

Colleagues at the University of Wisconsin in Madison have found that the mere anticipation of a fearful situation can activate two memory-forming regions of the brain: even before the event has occurred.

The investigators used functional MRI scans with 40 healthy participants who viewed aversive or neutral pictures preceded by predictive warning cues. Previous research reported sex differences in the way in which memory and emotion interact: in women, memory associations were found with a region called the left amygdala. But the association was with the right amygdala in men. This new study refines these findings: they were confined to the ventral amygdala during picture viewing and delayed memory.

Both men and women who had previously been given an indication that gruesome pictures were going to be shown were more likely to remember them.

What this means is that the act of anticipation may play an important role in whether the memory of a tough experience remains fresh and vivid. This makes sense based on our own experiences of events: do you remember the fear associated with a visit to the dentist that built and built before you got there? That anticipation can itself modify the memories of an event.

The findings are published in this week’s issue of the Proceedings of the National Academy of Sciences. They have important implications for the treatment of some psychological conditions such as post-traumatic stress disorder (PTSD) and social anxiety that are often characterized by flashbacks and intrusive memories of upsetting events

We have long known that our memories are not like some video recording forever preserved within our neurons. Some memories are false, many change over time and others lose their emotional charge. It is possible to implant false memories in people, and by re-writing our own life stories we can change the narrative of our lives and how we react to life events.

Samuel Johnson once said that, “The true art of memory is the art of attention.”

I’m quite sure that he is correct, and this research proves it. I’ve always been blessed – or cursed – with a prodigious memory, to the extent of being able to remember the lab values on every patient that I ever saw during my clinical years, and when I was younger being able to read pages of a textbook from memory. I’m quite convinced that my memory is no better than anyone else’s: I’m just a little better at using it.

The trick to using my memory was discovering at an early age that I could remember virtually anything if I really focused my attention on it. So I would focus on the book to the exclusion of everything else for a minute or two. Rest for a minute and then do it again. To this day, that is the best technique that I know for laying down long-term memory. My father also had this faculty, and when I was a youngster he would tell me not to write down things like shopping lists or to construct “To do” lists. He told me that, “if you really have to remember things you will. And if you’re not interested in something you don’t need a “to do” list.”

I only use lists if I have to do something tedious. This is a good test for you. If something that you are doing really engages your attention it is likely one of your core desires, and there is no need to be writing down a list of things to do. If it does not, and you have to write everything down, it’s probably not a core desire. You may still need to write down an action plan, but that’s to get your creative juices flowing, not to stimulate your memory.

I have developed quite a number of techniques for improving memory and concentration. Some are home grown, others modified from methods and techniques that others have taught me. I’ve been collecting and testing them for years. I’m doing a lot of flying this week, so I shall have the time to be put some of them together into a free report. I shall let you know when it’s ready and if you ask, I shall send you a copy.

There is one important reason for writing down thoughts once you have done something, and that is to help them be part of your legacy. That’s a topic to which we are going to return many times in the next few weeks.

“What we anticipate seldom occurs, what we least expected generally happens.”
–Benjamin Disraeli, 1st Earl of Beaconsfield (English Statesman, Novelist and, in 1868 and from 1874-1880, British Prime Minister, 1804-1881)

The Canine Gandhi: Cats, Dogs and Interspecies Communication

“Thousands of years ago, cats were worshipped as gods. 
Cats have never forgotten this.”
–Unknown Author

I need to tell you about something remarkable, that, if you think about it, has amazing implications.

We have a new little kitten. An eight-week-old little girl, and already a brave explorer who wants to play with everyone. Interestingly, she is already strongly right-handed. (Yes there is clear evidence of handedness in most mammals, and even some fish. But in cats, dogs and horses it’s not always clear until they are a little older than this.)

The other cats are not best pleased by this turn of events. After all this is their house, even if they do have to put up with the occasional human and a large mobile rug called Shannon. Shannon is an enormous dog of questionable pedigree but extremely calm disposition, who just hates any kind of noise or commotion: she is the original gentle giant.

The humans in the house are tolerated only because they are the suppliers of food, treats and comfy laps.

After all, as an unknown author once pointed out,
“Dogs have owners. Cats have staff.”

Little kitten thought that with Shannon fast asleep on the floor, it would be fun to play with another cat called Hannah. Now Hannah’s an older and very dominant cat who survived in the wild for a year. She didn’t take kindly to the small ball of fluff skipping toward her. Little kitten did not have the wit to understand that Hannah’s taut, crouched posture and narrowed eyes were not an invitation to a game, but preparation for the pounce that would quickly generate a kitten-shaped snack. We were about to intervene when something remarkable happened.

Shannon, who had been busily stacking ZZZZZs, got up shambled forward and put her enormous head between cat and kitten. No sound was made. She didn’t look at either of the protagonists. She was just like a great big bouncer getting between a couple of drunks in a bar.

She just stood there, unmoving and implacable. Like the Black Knight in Monty Python and the Holy Grail, "You shall not pass!"

After a few moments the kitten realized that there’d be no way through, and went off in search of one of her toys. And Hannah cat saw that kitten tartar was off the menu. She slunk off to go and groom herself.

With which Shannon went back to her spot, lay down and promptly fell asleep again. She was soon back to a dream that involved a lot of running.

There can be absolutely no doubt about Shannon’s intent. She wanted to keep the peace, and she woke from sleep to do so. It’s not the first time that she’s protected the cats from harm.

Late at night a couple of weeks ago, we couldn’t get her to come in the house. She kept running back outside and growling. Very odd for a sweet natured creature who normally always comes running when called. It was only when I went outside for a third time that I realized that I’d been a bit slow. A few feet away was a large feral cat that we’d not seen before. He had Hannah cornered against a pillar and Shannon was trying to protect Hannah and chase the away the interloper.

As soon as the dumb humans got out of the way, Shannon saw the gatecrasher off the premises and escorted Hannah back into the house.

These can’t be unique examples of inter-species communication. Do you have either anecdotes or research to share?

“Always remember, a cat looks down on man, a dog looks up to man, but a pig will look man right in the eye and see his equal.”
–Sir Winston Churchill (English Statesman, British Prime Minister, 1940-1945 and 1951-1955, and, in 1953, Winner of the Nobel Prize in Literature, 1874-1965)

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