Brain Tease: The Tantalizing Challenge of Mapping the Mind
Image from Dr. Kristen Harris' digitized model of a human brain section, showing a dendrite (yellow) surrounded by axons (green) that connect to create synapses (red).
CREDIT: Kristen Harris, Cruise through Hippocampal Neuropil
What would it take to map the human brain?
Neurologist Kristen Harris has spent the past few years working to do just that. She and a team of postdoctoral researchers have been dissecting, imaging and digitally recreating a highly detailed, three-dimensional map of the human brain.
The process involves taking a small chunk of brain matter, slicing it thin enough to be viewed beneath a microscope and then using the information gleaned from each individual slide to reconstruct a 3D picture of the brain's interior sections.
Harris' work is part of the BRAIN Initiative, an effort to map the human brain proposed by the Obama administration on April 2, 2013. The initiative was inspired by the Human Genome Project, a similar effort to map the sequences that comprise human DNA.
Harris demonstrated her results, a complex 3D model of a small square of brain tissue, at the World Science Festival in New York City, at a panel entitled "Architects of the Mind."
This example section, which contains around 500 synapses, took Harris and her team several years to model. It's also smaller than a single red blood cell — less than 200 cubic microns.
"It's so tiny that if we were going to map the entire human brain at that level, we would have to repeat [this process] billions of times over," Harris explained.
Mapping the human brain is "an enormous challenge," neurologist R. Douglas Fields agreed, also speaking at the panel. "We've always tended to try to understand it in terms of analogies to the most current technology of the time … mechanics or hydraulics. Today we tend to think of the brain in terms of an electrical computer. It's humbling to think that the brain might not [work like] that at all."
Cognitive roboticist Murray Shanahan added, "It's probably right to say the brain isn't like a computer. Nevertheless, we can build computers that are like brains, which is a very different kind of thing."
Computers are also the best tools available for learning about the brain, but even the best computers are still only capable of agonizingly slow progress.
Harris's model is further complicated because scientists have yet to discover the exact functions of the structures she is so painstakingly mapping.
Among the most mysterious are glial cells, which surround and support neurons. These support cells are among the most numerous cells in the brain; Fields, whose work focuses on glial cells, calls them the "background" of the brain, the "glue" that holds the neurons together.
Yet despite this, or perhaps because of it, only a minority of brain studies focuses on glia, said Field. Until recently, many researchers regarded glia as little more than the support system for the more important neurons, in part because glia do not use electricity to communicate.
It was Albert Einstein who convinced the scientific community to pay more attention to glial cells — and he did it after he was dead. [See also: Hey Einstein! Is That You?]
Researchers who analyzed Einstein's brain in an attempt to better understand the characteristics of the physicist's genius found that Einstein's brain had only the average number of neurons, and his cerebral cortex was no bigger than average, either. Einstein's brain did, however, have bigger glial cells.
Glia reveal one of the main ways that the brain's functioning differs from a computer's. These cells are decentralized; they don't function with electricity, and yet they seem to play a significant role in brain function, providing far more than mere padding for the neurons.
The Revolution Will Be Roboticized
Given the immense challenges involved in creating computer representations of a brain, and possibly even the futility of the attempt, why even try? Shanahan offered two reasons.
"One is the scientific motivation. If we properly understand how [the brain] works, then we ought to be able to simulate it on our computer. We ought to be able to build computer models of it. Moreover, if we're able to build computer models, then that will help us understand it."
The second reason is to aid in the development of artificial intelligence. "By building models of the brain and understanding better how the brain works, then we might be in a position to build artifacts that have intelligence as we do."
Even a robot with the intelligence of a rat or a dog would be a tremendous achievement, Shanahan said. "Rats can do pretty clever things ... It might be quite handy to have robots with the intelligence of a rat." [See also: "A Rat is Smarter Than Google"]
Discussions of artificial intelligence often take a turn for the ethical and hypothetical, and "Architects of the Mind" was no different. Shanahan touched on the possibility of robots with a greater intelligence than humans, or robots intelligent enough to improve themselves.
True artificial intelligence is even further off than a working model of the human brain, but with each new development, it becomes more and more feasible that these ideas, once firmly in the realm of science fiction, could become reality within this century.
"I used to be very dismissive of these kinds of scenarios, these kinds of worries," Murray admits, "but I'm starting to take them a lot more seriously as the technology improves."
The full talk can be viewed via video on the World Science Festival's website.