The Future of the Mind (42 page)

The key to Dr. Markram’s Blue Brain project is the “neocortical column,” a module that is repeated over and over in the brain. In humans, each column is about two millimeters tall, with a diameter of half a millimeter, and contains sixty thousand neurons. (As a point of comparison, rat neural modules contain only ten thousand neurons each.) It took ten years, from 1995 to 2005, for Dr. Markram to map the neurons in such a column and to figure out how it worked. Once that was deciphered, he then went to IBM to create massive iterations of these columns.

He is the eternal optimist. In 2009, at a TED conference, he claimed he could finish the project in ten years. (Most likely, this will be for a stripped-down version of the human brain without any attachment to the other lobes or to the senses.) But he has claimed, “If we build it correctly, it should speak and have an intelligence and behave very much as a human does.”

Dr. Markram is a skilled defender of his work. He has an answer for everything. When critics say that he is treading on forbidden territory, he counters, “As scientists, we need to be not afraid of the truth. We need to understand our brain. It’s natural that people would think that the brain is sacred, that we shouldn’t tamper with it because it may be where the secrets of the soul are. But I think, quite honestly, that if the planet understood how the brain functions, we would resolve conflicts everywhere. Because people would understand how trivial and how deterministic and how controlled conflicts and reactions and misunderstandings are.”

When faced with the final criticism that he is “playing God,” he says, “I
think we’re far from playing God. God created the whole universe. We’re just trying to build a little model.”

IS IT REALLY A BRAIN?

Although these scientists claim that their computer simulation of the brain will begin to reach the capability of the human brain by around 2020, the main question is, How realistic is this simulation? Can the cat simulation, for example, catch a mouse? Or play with a ball of yarn?

The answer is no. These computer simulations try to match the sheer power of the neurons firing in the cat brain, but they cannot duplicate the way in which the regions of the brain are hooked together. The IBM simulation is only for the thalamocortical system (i.e., the channel that connects the thalamus to the cortex). The system does not have a physical body, and hence all the complex interactions between the brain and the environment are missing. The brain has no parietal lobe, so it has no sensory or motor connections with the outside world. And even within the thalamocortical system, the basic wiring does not respect the thinking process of a cat. There are no feedback loops and memory circuits for stalking prey or finding a mate. The computerized cat brain is a blank slate, devoid of any memories or instinctual drives. In other words, it cannot catch a mouse.

So even if it is possible to simulate a human brain by around 2020, you will not be able to have a simple conversation with it. Without a parietal lobe, it would be like a blank slate without sensations, devoid of any knowledge of itself, people, and the world around it. Without a temporal lobe, it would not be able to talk. Without a limbic system, it would not have any emotions. In fact, it would have less brain power than a newborn infant.

The challenge of hooking up the brain to the world of sensations, emotions, language, and culture is just beginning.

THE SLICE-AND-DICE APPROACH

The next approach, favored by the Obama administration, is to map the neurons of the brain directly. Instead of using transistors, this approach analyzes the actual neural pathways of the brain. There are several components to it.

One way to proceed is to physically identify each and every neuron and synapse of the brain. (The neurons are usually destroyed by this process.) This is called the anatomical approach. Another path is to decipher the ways in which electrical signals flow across neurons when the brain is performing certain functions. (The latter approach, which stresses identifying the pathways of the living brain, is the one that seems to be favored by the Obama administration.)

The anatomical approach is to take apart the cells of an animal brain, neuron by neuron, using the “slice-and-dice” method. In this way, the full complexity of the environment, the body, and memories are already encoded in the model. Instead of approximating a human brain by assembling a huge number of transistors, these scientists want to identify each neuron of the brain. After that, perhaps each neuron can be simulated by a collection of transistors so that you’d have an exact replica of the human brain, complete with memory, personality, and connection to the senses. Once someone’s brain is fully reversed engineered in this way, you should be able to have an informative conversation with that person, complete with memories and a personality.

No new physics is required to finish the project. Using a device similar to a meat slicer in a delicatessen, Dr. Gerry Rubin of the Howard Hughes Medical Institute has been slicing the brain of a fruit fly. This is not an easy task, since the fruit fly brain is only three hundred micrometers across, a tiny speck compared to the human brain. The fruit fly brain contains about 150,000 neurons. Each slice, which is only fifty-billionths of a meter across, is meticulously photographed with an electron microscope, and the images are fed into a computer. Then a computer program tries to reconstruct the wiring, neuron by neuron. At the present rate, Dr. Rubin will be able to identify every neuron in the fruit fly brain in twenty years.

The snail-like pace is due, in part, to current photographic technology, since a standard scanning microscope operates at about ten million pixels per second. (That is about a third of the resolution achieved by a standard TV screen per second.) The goal is to have an imaging machine that can process ten billion pixels per second, which would be a world record.

The problem of how to store the data pouring in from the microscope is also staggering. Once his project gets up to speed, Rubin expects to scan
about a million gigabytes of data per day for just a single fruit fly, so he envisions filling up huge warehouses full of hard drives. On top of that, since every fruit fly brain is slightly different, he has to scan hundreds of fruit fly brains in order to get an accurate approximation of one.

Based on working with the fruit fly brain, how long will it take to eventually slice up the human brain? “
In a hundred years, I’d like to know how human consciousness works. The ten- or twenty-year goal is to understand the fruit fly brain,” he says.

This method can be speeded up with several technical advances. One possibility is to use an automated device, so that the tedious process of slicing the brain and analyzing each slide is done by machine. This could rapidly reduce the time for the project. Automation, for example, vastly reduced the cost of the Human Genome Project (although it was budgeted at $3 billion, it was accomplished ahead of time and under budget, which is unheard of in Washington). Another method is to use a large variety of dyes that will tag different neurons and pathways, making them easier to see. An alternative approach would be to create an automated super microscope that can scan neurons one by one with unparalleled detail.

Given that a complete mapping of the brain and all its senses will take up to a hundred years, these scientists feel somewhat like the medieval architects who designed the cathedrals of Europe, knowing that their grandchildren would finally complete the project.

In addition to constructing an anatomical map of the brain, neuron by neuron, there is a parallel effort called the “Human Connectome Project,” which uses brain scans to reconstruct the pathways connecting various regions of the brain.

THE HUMAN CONNECTOME PROJECT

In 2010, the National Institutes of Health announced that it was allocating $30 million, spread out over five years, to a consortium of universities (including Washington University in St. Louis and the University of Minnesota), and a $8.5 million grant over three years to a consortium led by Harvard University, Massachusetts General Hospital, and UCLA. With this level of short-term funding, of course, researchers cannot fully sequence the entire brain, but the funding was meant to jump-start the effort.

Most likely, this effort will be folded into the BRAIN project, which will
vastly accelerate this work. The goal is to produce a neuronal map of the human brain’s pathways that will elucidate brain disorders such as autism and schizophrenia. One of the leaders of the Connectome Project, Dr. Sebastian Seung, says, “
Researchers have conjectured that the neurons themselves are healthy, but maybe they are just wired together in an abnormal way. But we’ve never had the technology to test that hypothesis until now.” If these diseases are actually caused by the miswiring of the brain, then the Human Connectome Project may give us an invaluable clue as to how to treat these conditions.

When considering the ultimate goal of imaging the entire human brain, sometimes Dr. Seung despairs of ever finishing this project. He says, “
In the seventeenth century, the mathematician and philosopher Blaise Pascal wrote of his dread of the infinite, his feeling of insignificance at contemplating the vast reaches of outer space. And as a scientist, I’m not supposed to talk about my feelings.… I feel curiosity, and I feel wonder, but at times I have also felt despair.” But he and others like him persist, even if their project will take multiple generations to finish. They have reason to hope, since one day automated microscopes will tirelessly take the photographs and artificially intelligent machines will analyze them twenty-four hours a day. But right now, just imaging the human brain with ordinary electron microscopes would consume about one zettabyte of data, which is equivalent to all the data compiled in the world today on the web.

Dr. Seung even invites the public to participate in this great project by visiting a website called EyeWire. There, the average “citizen scientist” can view a mass of neural pathways and is asked to color them in (staying within their boundaries). It’s like a virtual coloring book, except images are of the actual neurons in the retina of an eye, taken by an electron microscope.

THE ALLEN BRAIN ATLAS

Finally, there is a third way to map the brain. Instead of analyzing the brain by using computer simulations or by identifying all the neural pathways, yet another approach was taken with a generous grant of $100 million from Microsoft billionaire Paul Allen. The goal was to construct a map or atlas of the mouse brain, with the emphasis on identifying the genes responsible for creating the brain.

It is hoped that this understanding of how genes are expressed in the
brain will help in understanding autism, Parkinson’s, Alzheimer’s, and other disabilities. Since a large number of mouse genes are found in humans, it’s possible that findings here will give us insight into the human brain.

With this sudden infusion of funds, the project was completed in 2006, and its results are freely available on the web. A follow-up project, the Allen Human Brain Atlas, was announced soon afterward, with the hope of creating an anatomically and genetically complete 3-D map of the human brain. In 2011, the Allen Institute announced that it had mapped the biochemistry of two human brains, finding one thousand anatomical sites with one hundred million data points detailing how genes are expressed in the underlying biochemistry. The study confirmed that 82 percent of our genes are expressed in the brain.

“Until now, a definitive map of the human brain, at this level of detail, simply hasn’t existed,” says Dr. Allen Jones of the Allen Institute. “
The Allen Human Brain Atlas provides never-before-seen views into our most complex and most important organ,” he adds.

OBJECTIONS TO REVERSE ENGINEERING

Scientists who have dedicated their lives to reverse engineering the brain realize that decades of hard work lie ahead of them. But they are also convinced of the practical implications of their work. They feel that even partial results will help decode the mystery of mental diseases that have afflicted humans throughout our history.

The cynics, however, may claim that, after this arduous task is finished, we will have a mountain of data with no understanding of how it all fits together. For example, imagine a Neanderthal who one day comes across the complete blueprint for an IBM Blue Gene computer. All the details are there in the blueprint, down to the very last transistor. The blueprint is huge, taking up thousands of square feet of paper. The Neanderthal may be dimly aware that this blueprint is the secret of a super-powerful machine, but the sheer mass of technical data means nothing to him.

Similarly, the fear is that, after spending billions deciphering the location of every neuron of the brain, we won’t be able to understand what it all means. It may take many more decades of hard work to see how the whole thing functions.

For example, the Human Genome Project was a smashing success in sequencing all the genes that make up the human genome, but it was a huge disappointment for those who expected immediate cures for genetic diseases. The Human Genome Project was like a gigantic dictionary, with twenty-three thousand entries but no definitions. Page after page of this dictionary is blank, yet the spelling of each gene is perfect. The project was a breakthrough, but at the same time it’s just the first step in a long journey to figure out what these genes do and how they interact.

Similarly, just having a complete map of every single neural connection in the brain does not guarantee that we will know what these neurons are doing and how they react. Reverse engineering is the easy part; after that, the hard part begins—making sense of all this data.

THE FUTURE

But assume for now that the moment has finally arrived. With much fanfare, scientists solemnly announce that they have successfully reverse engineered the entire human brain.

Then what?

One immediate application is to find the origins of certain mental diseases. It’s thought that many mental diseases are not caused by the massive destruction of neurons, but by a simple misconnection. Think of genetic diseases that are caused by a single mutation, like Huntington’s disease, Tay-Sachs, or cystic fibrosis. Out of three billion base pairs, a single misspelling (or repetition) can cause uncontrollable flailing of your limbs and convulsions, as in Huntington’s disease. Even if the genome is 99.9999999 percent accurate, a tiny flaw might invalidate the entire sequence. That is why gene therapy has targeted these single mutations as possible genetic diseases that can be fixed.