Wednesday, December 30, 2015

No Brainer.

For decades now, I have been haunted by the grainy, black-and-white x-ray of a human skull.

It is alive but empty, with a cavernous fluid-filled space where the brain should be. A thin layer of brain tissue lines that cavity like an amniotic sac. The image hails from a 1980 review article in Science: Roger Lewin, the author, reports that the patient in question had “virtually no brain”. But that’s not what scared me; hydrocephalus is nothing new, and it takes more to creep out this ex-biologist than a picture of Ventricles Gone Wild.

What scared me was the fact that this virtually brain-free patient had an IQ of 126.

He had a first-class honors degree in mathematics. He presented normally along all social and cognitive axes. He didn’t even realize there was anything wrong with him until he went to the doctor for some unrelated malady, only to be referred to a specialist because his head seemed a bit too large.

It happens occasionally. Someone grows up to become a construction worker or a schoolteacher, before learning that they should have been a rutabaga instead. Lewin’s paper reports that one out of ten hydrocephalus cases are so extreme that cerebrospinal fluid fills 95% of the cranium. Anyone whose brain fits into the remaining 5% should be nothing short of vegetative; yet apparently, fully half have IQs over 100. (Why, here’s another example from 2007; and yet another.) Let’s call them VNBs, or “Virtual No-Brainers”.

The paper is titled “Is Your Brain Really Necessary?”, and it seems to contradict pretty much everything we think we know about neurobiology.(...)

So on and off for the past twenty years, I’ve lain awake at night wondering how a brain the size of a poodle’s could kick my ass at advanced mathematics. I’ve wondered if these miracle freaks might actually have the same brain mass as the rest of us, but squeezed into a smaller, high-density volume by the pressure of all that cerebrospinal fluid (apparently the answer is: no). While I was writing Blindsight— having learned that cortical modules in the brains of autistic savants are relatively underconnected, forcing each to become more efficient— I wondered if some kind of network-isolation effect might be in play.

Now, it turns out the answer to that is: Maybe.

Three decades after Lewin’s paper, we have “Revisiting hydrocephalus as a model to study brain resilience” by de Oliveira et al. (actually published in 2012, although I didn’t read it until last spring). It’s a “Mini Review Article”: only four pages, no new methodologies or original findings— just a bit of background, a hypothesis, a brief “Discussion” and a conclusion calling for further research. In fact, it’s not so much a review as a challenge to the neuro community to get off its ass and study this fascinating phenomenon— so that soon, hopefully, there’ll be enough new research out there warrant a real review.

The authors advocate research into “Computational models such as the small-world and scale-free network”— networks whose nodes are clustered into highly-interconnected “cliques”, while the cliques themselves are more sparsely connected one to another. De Oliveira et al suggest that they hold the secret to the resilience of the hydrocephalic brain. Such networks result in “higher dynamical complexity, lower wiring costs, and resilience to tissue insults.” This also seems reminiscent of those isolated hyper-efficient modules of autistic savants, which is unlikely to be a coincidence: networks from social to genetic to neural have all been described as “small-world”. (You might wonder— as I did— why de Oliveira et al. would credit such networks for the normal intelligence of some hydrocephalics when the same configuration is presumably ubiquitous in vegetative and normal brains as well. I can only assume they meant to suggest that small-world networking is especially well-developed among high-functioning hydrocephalics.) (In all honesty, it’s not the best-written paper I’ve ever read. Which seems to be kind of a trend on the ‘crawl lately.)

The point, though, is that under the right conditions, brain damage may paradoxically result in brain enhancement. Small-world, scale-free networking— focused, intensified, overclocked— might turbocharge a fragment of a brain into acting like the whole thing.

Can you imagine what would happen if we applied that trick to a normal brain?

by Peter Watts, The Crawl |  Read more:
Image: de Olivera et al