The past decade has seen a revolution in our understanding of the brain. Functional magnetic resonance imaging (fMRI) gives scientists a view of our deepest thoughts and hidden anxieties. Tiny arrays of electrodes that record neural signals from the different parts of the brain reveal clues to the way our neurons encode and send information. But what discoveries will the next generation of technologies bring to neuroscience? Scientists at MIT hope to hurry along that answer with the McGovern Institute Neurotechnology Program, a new program dedicated to the development of novel neurotechnologies. Charles Jennings, newly hired director of the program, talks with Technology Review about his vision for the future.
Technology Review: Why start a specific program to develop neurotechnologies?
Charles Jennings: Neuroscience has always been both driven and limited by the technologies available to study it. The brain is so challenging–you need ways to record from and stimulate it. The power with which you can do these things determines the pace of the research and of the eventual clinical applications.
TR: What are the limitations of existing technologies for studying neuroscience?
CJ: For the most part, recording from the brain involves peering through the skull in ways that are fundamentally limited. FMRI, which was a great advance and one of the most powerful of these techniques, measures blood flow. So you can never get a better resolution than the speed of blood flow. You can never get down to the level of a single cell.
On the other end of the spectrum, we can stick an electrode into the brain, usually of animals, a technique that has been tremendously important. But mostly we can only record from one or several of the billions of neurons in the brain. Lots of information is encoded in the timing of the signals between neurons, which you can’t see unless you record from lots of neurons at once.
We’re also limited by the duration which we can record. If you want to study a process or behavior that takes weeks to acquire, you need to be able to look at the brain over long periods of time. That capability would open up many research questions: the processes that underlie habit formation, long-term degeneration, such as Alzheimer’s, or psychiatric diseases, which often develop over years.
Long-term recording is also important clinically for brain-stimulation treatments for Parkinson’s disease and depression. [In this procedure, an electrode is surgically implanted into part of the brain involved in the disease. Delivering electrical pulses via the implant blocks the electrical signals causing tremors and other symptoms of Parkinson’s disease, and, more recently, it has shown some promise in treating severe depression.] And it’s important in prosthetic devices for paralysis victims, in which a device records from the part of the brain involved in planning and then translates that activity into movement of a computer cursor or artificial limb. The challenge is to create something you can implant in the brain that will behave consistently over long periods of time.
TR: What are some interesting new technologies you see on the neuroscience horizon?
CJ: I think we’re going to see a big impact from human genetics. Our neighbors at the Broad [Institute], for example, have developed tools to look at individual variations in our genetic information and are looking for genes involved in schizophrenia and bipolar disorder. (See “A New Map for Health.”) Few genes have been identified so far, so there is really an urgent need to uncover the genetic basis of these diseases.
One of the trends we’ve seen in the last year or two is interest in combining genetics and brain imaging. If you identify a gene involved in psychiatric disease, you want to ask how that gene affects behavior and how it affects brain function. The brain is a black box until you look into it. The biggest challenge will be drawing all the connections between genes and behavior. How do environmental influences interact with genetics to shape the brain and influence behavior?
TR: What kinds of technologies do you want to develop?
CJ: So far, we are collaborating with Ian Hunter, a professor of mechanical engineering at MIT, who is developing nanowire electrodes that are much finer than current electrodes. (See “Tiny Electrodes for the Brain.”) You can feed them into more parts of the brain while doing less damage to the tissue.
Another project is to develop new methods for fMRI. We want to create reporter molecules that are sensitive to different [chemicals] in the brain, such as calcium, an important signaling molecule. A marker that changes with calcium concentration could image neural activity with much greater resolution than current methods.
In the long term, we want to think big–high-risk, high-payoff projects. If you look at fMRI, it’s a radical new way of looking at the brain. What will replace it 20 years down the line? The sci-fi view would be miniature devices that would lodge in the capillaries and record from close-by neurons and transmit that data through the skull. Think what you could do if you had high numbers of these things that could power themselves and swarm around the brain. We don’t know if it can be done, but I’ve been told there is no theoretical reason why it couldn’t.