It’s time to return to reality. We’ve each got one life to live, and one brain to do it with. In the end, every important goal in life boils down to changing our brains. We are blessed with natural mechanisms for transformation, but we find their limitations frustrating. Beyond appealing to our curiosity and sense of wonder, can neuroscience give us new insights and techniques for changing ourselves?
I’ve argued that one of the most important ideas of our time is connectionism, the doctrine that emphasizes the importance of connections for mental function. According to this notion, changing our brains is really about changing our connectomes. Connectionism dates back to the nineteenth century, but empirical evaluation of its claims has been difficult. At long last, thanks to the emerging technologies of connectomics, we are poised to test the doctrine. Is it indeed true that minds differ because connectomes differ? If we succeed in answering that question, we will also be able to identify desirable changes in the brain’s wiring.
The next step will be to devise new methods of promoting such changes, based on molecular interventions that promote the four R’s: reweighting, reconnection, rewiring, and regeneration. The methods would also utilize training regimens that harness the four R’s to bring about positive changes.
To realize all these advances, we must continue to develop the necessary technologies. In the history of science, there are many examples of conceptual barriers that could not be surmounted by researchers, however brilliant they were, until the right tools became available. You wouldn’t expect a caveman to figure out the workings of an old-fashioned mechanical clock if he didn’t have a screwdriver. In the same vein, it’s unrealistic to expect neuroscientists to figure out the brain without extremely sophisticated tools. Our technologies are starting to become equal to the task, but we will need to make them many times more powerful.
We need to create a research environment that fosters these technological advances. One possibility is to undertake “grand challenges,” ambitious projects that stimulate our imagination and mobilize our intellectual efforts. We could set a goal of finding the entire neuronal connectome of a mouse brain using electron microscopy, or the entire regional connectome of a human brain with light microscopy. The projects are of comparable difficulty, because they require the acquisition and analysis of similar amounts of data. I estimate that either would require a decade of intense effort. Both connectomes would be invaluable resources for neuroscientists, just as genomes have become indispensable to biologists.
These projects would be enormously difficult, but we could simultaneously pursue shortcuts. With the technologies developed, it would be possible to rapidly and cheaply find smaller connectomes. Compared with the grand challenges above, it should be a thousand times faster to find the neuronal connectome of a cubic millimeter of brain, or the regional connectome of a mouse brain. Finding many smaller connectomes would be important for studying individual differences and change.
Why should we invest in future technologies when we need to find better treatments for mental disorders right now? I think we should do both. Our therapies will surely improve over the next few years, but I expect that it will take decades to find true cures. Since this will be a continuing battle, it’s worth making a reasonable investment today to reap rewards in the long run.
You may be skeptical that technology will ever progress enough to find connectomes quickly and cheaply. Before the Human Genome Project began, sequencing an entire human genome seemed almost impossible too. Connectomics might look difficult, but there’s a certain sense in which it’s trivial compared with the larger endeavor of neuroscience. Since the goal is well defined, we know exactly what success means, and can quantify progress. In contrast, the broader goal of neuroscience—to understand how the brain works—is only hazily defined. Even the experts don’t agree about what it means. Once a goal is clearly defined, time, money, and effort are likely to yield progress. That’s why I believe that connectomics will achieve its goals, however ambitious they might seem. We just need to rise to the challenge.
The young boy laughed as he splashed in the water. Returning to land, he asked, “Teacher, why does the stream flow?” The old man gazed silently at the novice and replied, “Earth tells water how to move.” During their journey back to the temple, they crossed a precarious footbridge. The novice clutched the old man’s hand tightly. He looked at the stream far below and asked, “Teacher, why is the canyon so deep?” As they reached the safety of the other side, the old man replied, “Water tells earth how to move.”
I believe the stream inside our brain works in much the same way. The flow of neural activity through our connectomes drives our experiences of the present and leaves behind impressions that become our memories of the past. Connectomics marks a turning point in human history. As we evolved from apelike ancestors on the African savannah, what distinguished us was our larger brains. We have used our brains to fashion technologies that have given us ever more amazing capabilities. Eventually these technologies will become so powerful that we will use them to know ourselves—and to change ourselves for the better.