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Neurosurgeon leans on research to improve patient care

Daniel Cleary, M.D., Ph.D., left career in computer science, now conducts research to better understand circuits in the world’s most complex computer — the human brain
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Dan Cleary - Research Week 2024. Cleary is tall with dark short hair, smiling. Wearing a gray suit and black tie, standing in an office at the OHSU Center for Health and Healing.

Daniel Cleary, M.D., Ph.D., once thought of the brain as a very sophisticated computer.

Cleary grew up and went to college in Montana, where he majored in computer science, with minors in biology, chemistry and mathematics. He saw a bright future as a computer programmer or electrical engineer.

As he neared graduation, though, his focus shifted.

“When I looked at careers in computer science, a lot of my friends sat around all day alone in a cubicle,” he said. “I wanted a career where I was more involved directly with people and making a real contribution to their day-to-day lives.”

Today, Cleary, assistant professor of neurological surgery in the Oregon Health & Science University School of Medicine, is a functional neurosurgeon with a dual focus on advancing research. The goal is to better understand the circuitry connecting the 100 billion neurons comprising “the most fantastically complex organ on Earth,” in the words of another OHSU neuroscientist.

Indeed, Cleary recognizes the brain-as-computer metaphor only goes so far.

“The computer analogy falls apart at finer levels,” he said. “With computers, we understand everything because we made them. There is so much more to the brain, so many different layers and subtle complexity, that we just don’t understand yet.”

Revealing those layers is the focus of his research.

Cleary earned his M.D. and Ph.D. at OHSU. Later, as a postdoctoral fellow at the University of California San Diego, Cleary joined with electrical engineering professor Shadi Dayeh, Ph.D., and collaborators at OHSU — including Ahmed Raslan, M.D., now interim chair of neurological surgery in the OHSU School of Medicine — to design an extremely small, thin electrode that sits on the brain’s surface during surgery. Known as electrocorticography, the standard ECoG measures brain activity with between 16 and 64 electronic sensors. The new electrode has thousands of sensors.

A study by Dayeh, Raslan, Cleary and colleagues published in January of 2022 demonstrated the reliability of grids with 1,024 or 2,048 sensors. A more recent study, published on April 24, expands the concept.

“It provides some amazing insights into how the human brain works on the microscopic level,” Cleary said.

As a neurosurgeon, he has the rare opportunity to directly access the human brain, while also applying what he’s learned to improve people’s lives. Better understanding can translate into more targeted, less invasive surgeries and better outcomes for patients.

One startling advancement in minimally invasive surgery stands out — a type of cutting-edge brain surgery that involves no cutting at all.

Cleary returned to OHSU in June of 2022 to join Raslan as the two neurosurgeons involved in Oregon’s only center to provide high-frequency focused ultrasound to alleviate uncontrolled tremor. Right now, Cleary and Raslan alternate each Wednesday with a lineup of patients seeking relief from a debilitating condition.

“That’s honestly my favorite day of the week,” Cleary said. “With focused ultrasound, the patients spend an hour in the MRI, without the need for anesthesia or breathing tubes, and as soon as they’re done, they see the benefit.

“Probably half the time, somebody is crying because the impact of relieving their tremor is just so emotional. That’s an amazing day for me, too.”

Cleary, 42, has plenty to do outside of work. He is raising 6-year-old twins with his wife, a central Oregon native, in the Portland area.

He’s excited for the future of neurosurgery, thanks largely to the research occurring now.

“I started out as a computer scientist with an interest in programming and circuits and building electronics. That’s what led me into neuroscience and neurosurgery,” he said. “Now, I’m focused on understanding and modulating circuits of the brain. How can we make them better? How can we fix the neural circuits to improve patient care?”

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