Xi Luo


Xi Luo

Assistant Professor of Biostatistics

Mike Cohea/Brown University
Functional magnetic resonance imaging can go only so far. Understanding how different regions of the brain work together and how that can go wrong in disease requires a biostatistician, which is what drew Xi Luo to the field.

Growing up in Sichuan Province, Xi Luo would hear this wise, if not ancient, saying: “If you learn mathematics, physics, and chemistry well, you can walk around and have no fear.”

He took the wisdom to heart in high school. In 1998 he won a bronze medal in China’s national physics “Olympiad” competition after earning the gold medal at the provincial level. From there, he became a star student at Peking University, where he studied geophysics.

Clearly Luo had found a true talent in quantitative science, but it was not until after he began graduate school at Yale in 2003 that he found his true interest: the biostatistics of the brain. This summer that journey of self-discovery (6,400 miles from home by the most direct route) brought him to Brown as a new assistant professor of biostatistics.

“We were using mathematical models to understand geophysical systems,” said Luo. “I realized that I was interested in a much broader sense of the science, especially in biology, so I transferred to statistics, which enabled me to use the same bag of tools to study biology-related problems.”

At Yale, Luo increasingly began collaborating with Chiang-Shan “Ray” Li, a brain surgeon-turned-psychiatry professor. As the two pored over functional magnetic resonance imaging “brain scans,” Luo contributed statistical models of the interactions between brain regions.

In 2009 the pair and co-authors published a paper in the Journal of Neuroscience showing the distinct roles that two different brain regions — the inferior prefrontal cortex and the presupplementary motor area — play as they work together to endow people with a certain measure of self control. The subjects had been primed to “go” in response to a signal, but then had to hold back and stop when they were shown the occasional stop signal.

Figuring out how the brain’s parts work together has remained Luo’s motivation ever since.

“My objective is trying to investigate and understand brain networks,” Luo said. “We want to understand how different regions of the brain collaborate with each other so that human beings can perform certain tasks.”

This aspect of brain science is a statistician’s job because it is much too invasive to directly tap the flows of electrical current and neurotransmitters in the brain of a living, thinking, behaving human being. Instead, researchers use indirect measurements, such as fMRI scans, to see what regions are active and when, and then statistically analyze the resulting data. A simplified version of a typical question might be, “How strongly is the activity recorded in this region at time Y correlated with, and therefore a likely response to, the activity recorded in that other region at time X, when the subject was exposed to the stimulus?”

This kind of research, in addition to providing important basic insights, could have clinical implications, Luo said. Once healthy interactions are understood and recognizable, doctors might then be able to recognize when they start to go awry.

“If you understand the collaborations within the brain, you can use that to do early detections of certain diseases like ADHD, Alzheimer’s and other mental disorders,” Luo said. “That’s the goal. We’re getting there but not quite yet.”

For example, in a paper in the Proceedings of the National Academy of Sciences in 2010, Luo, Li and collaborators published a paper illuminating some traits that might help predict how well a cocaine-dependent person will respond to a drug therapy intended to help them regain greater self-control.

What drew Luo to Brown is the chance to work on these kinds of projects with a strong community not only of fellow biostatisticians, but also researchers and physicians in the Brown Institute for Brain Science and the Department of Psychiatry and Human Behavior.

“This fits into my career goal of trying to understand the brain,” he said, ”and so I’m glad I get to come here and work with those wonderful people.”

In more ways than one, such collaborations to figure out how brain regions interact will be a true meeting of the minds.