What are you working on?

I work on the theory of neural networks. In my field, we are trying to understand how all mental phenomena arise from the brain. Specifi cally, we want to understand this in terms of interactions between single neurons. It is basically a reductionist approach. We are trying to explain brain function, from a microscopic point of view, as an outcome of interactions among a very large group of neurons inside the brain. It’s analogous to physicists understanding properties of a piece of matter in terms of its atoms.

One thing we’ve been working on is the question of how humans and animals learn from experience. We are trying to formulate mathematical theories that explain how learning might take place through changes in the connections between neurons. The hypothesis is that each time you learn something based on reward or punishment, the synapses in your brain get changed. How does this happen? That’s the question.

Another thing we are interested in these days, which is a departure for this lab, is the structure of the brain. We would like to know if it is possible to make a complete circuit diagram of the brain in the same way that you would for a computer. Let’s say you wanted to understand a computer. You might look inside the computer, find every transistor, gure out how it is connected to other transistors, and make a huge list. We are part of a collaboration that wants to find new ways of doing that for human and animal brains.

What recent changes in and around your field have affected your work?

In the fi eld of neuroscience, the big changes have occurred in our ability to measure things that could never be measured before––activity in certain areas of the brain, activity of neurons, concentrations of various chemicals, and now the microstructure of the brain. There are many different ways of looking at things. For instance, we can use the naked eye. If you dissected a brain you could actually see its structure. Of course, we can also look at it under a microscope and see an entirely new set of things that previously had been unrevealed. And now we can use an electron microscope that allows us to examine at an even higher resolution. We can see down to the level of single synapses and examine the connections between individual neurons. This enables us to visualize thestructure and function of the human brain. These are the big stories in neuroscience and they certainly have had a big influence.

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