EO-FLIM turns neuron sparks into readable brain signals

At the Salk Institute, biophysicist Adam Bowman has refined electro-optic fluorescence lifetime imaging microscopy (EO-FLIM), a method that tracks how long fluorescent signals persist after a fast laser pulse—revealing the electrical handoff between individual

On a bench at the Salk Institute for Biological Studies in La Jolla, Calif., Adam Bowman still works like the tinkerers in his family—except the machines are now microscopes, and the goal isn’t an airplane that flies. It’s a brain circuit that can be watched.

Bowman, 30 and trained in biophysics, comes from a line of builders. One grandfather worked on the engines of tractors and cars. The other owned a boat, which Bowman helped work on, and together they also built radio-controlled model airplanes. Today. he “continues to tinker” at Salk. aiming to make it easier for researchers to see how cells in the brain communicate with one another—technology he says could be applied to many diseases and disorders. including Parkinson’s. schizophrenia. autism and cancer.

Neurons communicate by sending tiny charges of electricity through their membranes. For decades, scientists have studied parts of this process by inserting fluorescent proteins into cells so the proteins glow. Most methods, Bowman explains, focus on brightness—how strong the light appears. His method. called electro-optic fluorescence lifetime imaging microscopy (EO-FLIM). instead looks at duration: how long the fluorescent proteins remain lit up after a fast laser pulse.

That timing, Bowman says, is what makes EO-FLIM powerful for tracking a signal’s passage from one cell to another—“a brain circuit in action.”

“It takes a really steady hand,” Bowman says, describing the methods he and his colleagues use to employ EO-FLIM in animal models. The steadiness is more than a technical detail. It’s the difference between observing a glow and reading the electrical message embedded in how that glow fades.

Several labs are now building EO-FLIM microscopes based on Bowman’s design. Some researchers. Bowman says. have used EO-FLIM to make better recordings of neuron activity in the brains of living fruit flies. The approach has been moving from an idea grounded in imaging physics toward a tool other scientists can pick up and run.

The promise is personal in a public way: Bowman hopes the method can help other scientists study how. in people with Parkinson’s. the brain loses its ability to send messages. He also sees another application closer to the cellular chaos of cancer: EO-FLIM could be used to detect the rapid division of cells that is a hallmark of cancer.

Bowman has kept developing EO-FLIM, but he also points to a stubborn reality for researchers who build tools rather than therapies. Turning a lab technique into marketable products takes time. With the success he’s had so far, though, he can see the fluorescent light at the end of the tunnel.

In a field where many imaging methods measure how bright a signal is, EO-FLIM’s focus on how long fluorescence lasts after a fast laser pulse is changing what scientists can pull out of the same underlying communication—one cell passing its electrical signal to another, repeatedly, as a circuit.

The portrait and video interview of Bowman were captured with special thanks to the Exploratorium in San Francisco. The piece is part of “The Young American Scientists,” an editorially independent project produced with financial support from Regeneron.

EO-FLIM electro-optic fluorescence lifetime imaging microscopy Adam Bowman Salk Institute biophysics neurons fluorescent proteins brain circuits Parkinson's schizophrenia autism cancer fruit flies microscopy