Ila Fiete studies how the brain performs complex calculations

While doing a postdoc about 15 years ago, Ila Fiete began looking for teaching jobs in computational neuroscience, a field that uses mathematical tools to investigate brain function. However, there were no advertised positions in theoretical or computational neuroscience at that time in the United States.

“It wasn’t really a field,” he recalls. “That has completely changed, and [now] there are 15 to 20 vacancies advertised per year. “He ended up finding a position at the University of Texas at Austin Center for Learning and Memory, which along with a handful of universities, including MIT, was open to neurobiologists with computer experience .

Computing is the cornerstone of Fiete’s research at MIT’s McGovern Institute for Brain Research, where he has been a faculty member since 2018. Using computational and mathematical techniques, he studies how the brain encodes information in ways that allow cognitive tasks such as learning, memory, and reasoning about our environment.

An important area of ​​research in Fiete’s laboratory is how the brain can continually calculate the body’s position in space and make constant adjustments to that estimate as we move.

“When we walk the world, we can close our eyes and still have a very good estimate of where we are,” she says. “This implies being able to update our estimate based on our sense of self-movement. There are also many calculations in the brain that involve moving through abstract or mental space rather than physical space, and integrating speed signals of one variety or another. Some of the same ideas and even circuits for space navigation could be involved in navigating through these mental spaces. “

No better fit

Fiete spent his childhood between Mumbai, India and the United States, where his mathematician father held a series of visiting or standing appointments at the Institute for Advanced Study in Princeton, NJ, the University of California at Berkeley, and the University of Michigan at Ann Arbor.

In India, Fiete’s father did research at the Tata Institute for Fundamental Research, and she grew up spending time with many other children of academics. She was always interested in biology, but she also enjoyed mathematics, following in her father’s footsteps.

“My father was not a practical father, he wanted to teach me a lot of math or even wonder how my math school work was going, but the influence was definitely there. There is a certain aesthetic to mathematical thinking, which I absorbed very indirectly, “she says. “My parents didn’t push me into academics, but I couldn’t help but be influenced by the environment.”

He spent his last two years of high school at Ann Arbor and then went to the University of Michigan, where he majored in mathematics and physics. While there, she worked on undergraduate research projects, including two summer terms at Indiana University and the University of Virginia, which gave her her first-hand experience in physics research. Those projects covered a variety of topics, including proton radiation therapy, the magnetic properties of single crystal materials, and low-temperature physics.

“Those three experiences are what really assured me that I wanted to study academically,” says Fiete. “It definitely seemed like the path I knew best, and I think it suits my temperament better too. Even now, with more exposure to other fields, I can’t think of a better fit. “

Although she was still interested in biology, she only took one course on the subject in college, stopping because she didn’t know how to marry quantitative approaches to the biological sciences. She began her graduate studies at Harvard University planning to study low-temperature physics, but while there, she decided to start exploring quantitative classes in biology. One of them was a systems biology course taught by the then MIT professor Sebastian Seung, which transformed her professional career.

“It was really inspiring,” he recalls. “Thinking mathematically about interactive systems in biology was really exciting. It was really my first introduction to systems biology, and it got me hooked right away. ”

He ended up doing most of his PhD research in Seung’s lab at MIT, where he studied how the brain uses incoming signals from the speed of head movement to control the position of the eye. For example, if we want to keep our gaze fixed on a particular place while our head is moving, the brain must continually calculate and adjust the amount of tension required in the muscles around the eyes to compensate for head movement.

“Strange” cells

After earning her doctorate, Fiete and her husband, a theoretical physicist, went to the Kavli Institute for Theoretical Physics at the University of California at Santa Barbara, where they each held fellowships for independent research. While there, Fiete began working on a research topic he is still studying today: grid cells. Located in the entorhinal cortex of the brain, these cells allow us to navigate our surroundings by helping the brain create a neural representation of space.

Halfway through his position there, he learned of a new discovery, that when a rat moves through an open room, a grid cell in its brain fires in many different places geometrically arranged in a regular pattern of repetitive triangles. Together, a population of grid cells forms a network of triangles representing the entire room. These cells have also been found in the brains of several other mammals, including humans.

“It’s amazing. It’s this very crystal clear answer,” says Fiete. “When I read about it, I fell out of my chair. At the time, I knew this was a strange thing that would raise so many questions about brain development, function, and circuits that could be studied. computationally ”.

One question that Fiete and others have investigated is why the brain needs grid cells, since it also has so-called place cells that each fire at a specific location in the environment. One possible explanation that Fiete has explored is that grid cells of different scales, working together, can represent a large number of possible positions in space and also multiple dimensions of space.

“If you have a few cells that can parsimoniously generate a very large encoding space, then you can afford not to use most of that encoding space,” she says. “You can afford to waste most of it, which means you can separate things very well, in which case you don’t become as susceptible to noise.”

Since his return to MIT, he has also followed a research topic related to what he explored in his doctoral thesis: how the brain maintains neural representations of where the head is in space. In an article published last year, he discovered that the brain generates a one-dimensional ring of neural activity that acts like a compass, allowing the brain to calculate the current direction of the head relative to the external world.

His lab also studies cognitive flexibility – the brain’s ability to perform so many different types of cognitive tasks.

“How is it that we can reuse the same circuits and use them flexibly to solve many different problems, and what are the neural codes that are susceptible to that type of reuse?” she says. “We are also investigating the principles that allow the brain to connect multiple circuits to solve new problems without much reconfiguration.”