Beth Stevens, a Northeastern alumna and pioneering neuroscientist, has spent the better part of her research career transforming our understanding of how the brain is wired.

In a breakthrough study in 2012, Stevens discovered that cells called microglia not only protect the brain by reducing inflammation, but also “prune” bad synapses during brain development, ensuring that the brain is wired properly. The startling revelation also indicated that diseases such as Alzheimer’s, Huntington’s, and schizophrenia could stem from impaired microglial function and abnormal activation of this pruning mechanism.

“A major question still is what makes synapses vulnerable? Why do we lose our synapses?” said Stevens, an assistant professor in the Department of Neurology at Harvard Medical School and the F.M. Kirby Neurobiology Center at Boston Children’s Hospital. “If we could understand how synapses get lost, we may be able to think about novel approaches and novel therapeutics to protect those synapses.”

She was addressing a standing-room only crowd of students, faculty, and staff in the event space on the 17th floor of East Village on Thursday evening, reflecting on her life’s work before engaging in a lengthy conversation with Northeastern President Joseph E. Aoun. “Even though all of these disorders, ranging from Alzheimer’s to Huntington’s to schizophrenia, seem so different from one another, we hypothesize there may be some common pathways or common mechanisms that might underlie this synaptic loss,” she said. “And if so—if we can understand what that is—this may provide new insights into therapies.”

Here are four takeaways from the event:

Microglia, synapses, and neurological disorders

Microglia account for 10 percent of cells in the human brain, Stevens said, but she and other neurobiologists haven’t always studied them. “They’re immune-derived,” she explained, “so it wasn’t thought that these cells could play a normal role during development.”

That line of thinking has since gone out the window, however, particularly after scientists discovered that one of microglia’s primary roles is to “survey” the brain’s synapses. As Stevens put it, “Now we’re thinking about these cells in a completely different way.”

She and her lab colleagues wondered whether microglia could be involved in the pruning process. They knew these cells were particularly good at “eating things,” as Stevens put it, and they wondered whether they might be nibbling at synapses, leading to neurological disorders.

“We hypothesized that too much pruning by microglia through this mechanism could contribute to synapse loss and neurodevelopmental disorders such as autism and schizophrenia,” Stevens said. As it turned out, her lab’s findings suggested as much—that the normal pruning that takes place in children is somehow reactivated to drive synapse loss in the adult brain in diseases like autism, that impaired microglial function may play a role in causing them.

Awards, awards, awards

Stevens has received numerous awards for her groundbreaking work, including the Smith Family Award for Excellence in Biomedical Research, a Dana Foundation Award, and an Ellison Medical Foundation New Scholar in Aging Award. Last year, she was one of 24 people in the world to be named a MacArthur Fellow, which includes a five-year, $625,000 “genius grant.”

Stevens noted that the genius grant would allow her to expand her lab’s focus. “The MacArthur award has been catalytic in the sense that it’s now enabling us to tackle really tough questions that I may not have thought I could do before,” she said. “It also gave me the confidence to say ‘we’re just going to go for it.’ We’re going after some pretty hard questions, but I’m excited about it and we’ll see where it goes.”

Time for questions

Stevens spent more than half of the hourlong event answering questions from the audience in the room, social media, and Aoun himself, who asked Stevens to name some of the biggest challenges facing women looking to excel in the STEM fields. She suggested that more must be done to help women complete lengthy doctoral programs, particularly those who are juggling their career with raising children. “Having children when you’re a post-doc is very expensive and I don’t think the system is in place to support that,” she said. “We lose some very talented women at that stage.”

One student in the audience asked for advice on jumpstarting his STEM career. “If you’re excited about a career in science now, take advantage of as many opportunities as Northeastern can give you,” she said. “You can’t just sit back and hope something’s going to happen. You actually have to make it happen.”

Stevens, BPH’93, is a prime example. As an undergraduate in Northeastern’s medical laboratory science program, she did three co-ops in three different clinical labs, including one at the Sahlgrenska University Hospital in Sweden. “All of these experiences when you’re 20 years old, they can change your life,” she said last year, after winning the genius award. “It opened my eyes to what was out there.”

Fun yearbook photo

At the end of the Q-and-A, Aoun gifted Stevens a framed yearbook photo of herself from 1988, her first year at Northeastern. “I had ’80s hair,” Stevens said, eliciting laughter from the crowd. “I haven’t seen this picture in a long time. Thank you so much, this is really awesome.”