Brain Pruning: the answer to autism?

"In adults [the human brain] has perhaps 100 billion neurons, each connected to its neighbours by 5000 synapses or so." New Scientist, 1 October 2008

"In the f[o]etal brain, all parts of the brain are interconnected, but as we age, the connections are pruned.  If the pruning genes get it wrong, the connections are off." - according to Vilayanur S Ramachandran, in New Scientist, 8 January 2011 (The fastest brain in the west, p26)

There is no disputing that the human brain undergoes a pruning process whereby the synapses, the connections between neurons, are culled while the brain is developing.

This is a normal part of the development process: meaningful connections are retained, and [at least some] unused ones are discarded.  This is a rationalisation that begins before the baby is born and continues for years afterwards.

And it's those synapses that enable brain functionality, particularly connections between different areas, which facilitate all manner of associative thought and reasoning.


The second quote above was made in the context of neuroscientist Ramachandran's study of synaesthesia, the leaking of one sense into another (the most common example being seeing letters or numbers as specific colours).

Occam's razor says to me that it need not take Ramachandran's concept of "pruning genes" for the pruning process to go awry. Development both before and after birth are affected by quite a range of factors.

Yet it struck me that disruption to that process may account for high-functioning autistics [so called "savants"] in particular.  The ability of Daniel Tammet, for example, to recall thousands of digits by visualising the string as a rolling landscape - that sounds like abnormal connections remaining in place between disparate parts of the brain.

Incorrect pruning may account for autism in a wider sense - not just those that are high functioning - but it seems easier to look to that process when describing aberrantly strong functionality than a weakening of capability, which can be due to a much wider variety of factors.

Science, the universe, and beauty

Today my seven-year old was reading an article in New Scientist about diamonds, where it discussed alternatives for harder materials, and arrangements of chemical structures.

It was remarkable that he read for more than two pages on a subject - chemistry - for which he clearly had little to no understanding.  Especially since it's only been a few months since he attained sufficient fluidity in reading.

 I have already outlined some of the basics of chemistry to my seven- and eight-year-olds, but since they have no specific interest in it, it will be slow going for a while.

But it got me considering the periodic table.  I'd only done chemistry to sixth form (age 16), and I haven't refreshed systematically since.  So I glanced at the subject in Encyclopedia Britannica - one of their rare shows of colour was the periodic table, page 952 of volume 15.

It was in discussion of the chemical composition of the earth, and the origin of elements in stars, that I realised there was a whole new area of fundamental systematics for me to absorb with adult eyes.

And then I was reminded of a piece in today's Good Weekend: in Stephanie Dowrick's Inner Life column which tends, I guess, to discuss the secular spiritual.  (I'm not generally taken by her, preferring the following columnist, Mark Dapin, who is surprisingly readable for a magazine humour column.)

Dowrick was querying one's "eye for beauty".  Looked like she was focusing on the visually beauty, but she eventually redeemed herself with other examples: children, poetry, music.

Of course, I find beauty in the analytical, in making sense of things that provide an internal logic and coherency.  The more fundamental the better, such as physics, evolutionary biology... and chemistry.  To see natural patterns and logic that are inherent and immutable: they describe a natural rhythm, a joyous music of the universe that is unsullied by human hand.

It takes a particular temperament to find joy in that sort of beauty*.  I feel privileged.





*One who does is someone I've previously mentioned, Daniel Tammet, a savant with Asperger's, who finds beauty in numbers.  That's numbers for themselves, as opposed to beauty in more complex mathematics, for which I have given a wonderful example here.

The Amazing Brain 3: Daniel Tammet (again)

I've just finished reading Daniel Tammet's autobiography, Born On A Blue Day.

It's a very easy read, very engaging, and fascinating.

Tammet was born with high-functioning autism in England in 1979. It's a significant disability, beyond question, but there are compensations.

He has found it hard to manage many aspects of life, because of the way his brain is wired. It could be said that it has been difficult for him to apply an appropriate amount of focus to many day-to-day tasks. On some, he spends too much time because he is over-stimulated by the physical or numerical aspects of the task. On others, he doesn't understand enough of what is required, because it's something in which his mind simply doesn't engage.
For example, human interaction has been particularly difficult for him. His mind doesn't process the simple physical and verbal cues that most of us take for granted.

On the other hand, he has a special affinity for numbers - and languages. An overcompensating affinity, in some ways, yet something that enables him to appreciate beauty. Albeit of a different type to what most people understand.


He has eventually learnt mechanisms to deal with many of his obstacles, and to make the most of his abilities.

He first came to notice when he offered to memorise and recite pi for over 22,000 digits, as a fund-raiser for epilepsy, which he has suffered.

That illustrates two aspects about him: his ability and his humanity.

His abilities includes a prodigious memory, very very high maths calculation capacity, and synesthesia. The latter is a tendency for some senses to bleed into others. For example, he sees words as particular colours, and numbers as particular shapes.

He can calculate the product of two large numbers by visualising the two numbers as shapes, where the space between them is another shape, which is the answer.


And incredibly, despite his difficulty with human interaction, he is a very humble, honest, warm person. Something we should all be striving for.

More to come about his abilities. Meanwhile, I thoroughly recommend the book.

Tech: The tech personality 2: three mathematicians

I was struck by the profiles of three people who have a mathematical aptitude of one sort or another.

For some people, mathematics takes work. For some, it comes easy. For others, it's an art form.


Australian Terence Tao is the youngest ever winner of the Fields medal, the "Nobel of maths". His mathematical interests are wide-ranging, and he appears particularly well-adjusted.

Russian Grigory Perelman was also awarded a Fields. He declined it because they didn't understand his work - a mite unfair, because you don't need to understand some maths in full to appreciate its truth, beauty and relevance. The Fields was awarded to him anyway. He has apparently solved a very important puzzle - which will probably fetch him the million-dollar millenium prize. He apparently withdrew from mathematics in protest against a perceived lack of ethics in certain people in the upper echelons of maths. Currently unemployed.

Englishman Daniel Tammet has Asperger's Syndrome and, unusually, some insight into his condition. He also has an eidetic memory. He can recite pi to 22,000 places - "as beautiful as the Mona Lisa". He can multiply numbers in his head very easily - as does Tao - but interestingly, he can't do square roots (as some can), and can't do abstractions such as polynomials.

Three very different personalities. All very interesting. I can appreciate them from my love of mathematics, although they're leagues above me.

Here are their Wikipedia entries: Tao , Tammet, and Perelman.
And here's some interesting press about them: Tao, Tammet, and Perelman.

All six articles are worth a read.