Fenna Krienen

When it comes to unlocking the secrets of the brain, there is strength in numbers, as Fenna Krienen’s work on the human connectome shows. Connectomics — a word and concept modeled on genomics — represents a new kind of cartography, an attempt to trace connections between neurons in the brain.

The scope of the project is massive. “To set the stage,” says Krienen, “you have 100 billion neurons, and trillions of connections.” Even the most advanced computers can’t model such a complex neural network directly. Instead, “every one of the pixels in our images is pooling data over thousands or tens of thousands of neurons,” she says. The data are further simplified by computational tools that look for consistent patterns of activity across participants over a large sample size. Traditionally, neuroimaging studies of the human brain relied on between twelve and thirty subjects at a time, Krienen says; her lab is looking at thousands of brains at once, trying to learn how neural networks form and break down with age or disease.

She’s inspired by the idea that her lab’s work has the potential to upend the long-held assumption “that the human brain is either just a bigger version of a small brain, or is basically the same as other primate brains.” Preliminary results indicate that this might not be the case. “There is a difference not just in scale,” Krienen says, “but also in organization of what’s new. What is expanded is not just more of the same.”