Christina Kim

Christina Kim, 33, developed a technique to identify the nerve cells involved in different animal behaviors—which could lead to better treatments for neuropsychiatric conditions like depression, anxiety, and drug and alcohol addiction. 

In both human and animal brains, nerve cells—also called neurons—encompass hundreds of cell types. It’s long been difficult to detect which types are activated in response to a particular stimulus, like a loud noise, strong smell, or drug injection. Past methods of recording different types of neural activity in mice, whose brains have many similarities to humans’, were limited to specific brain areas, or they inhibited the behaviors researchers hoped to study.

Kim’s method, which she developed as a postdoctoral researcher at Stanford, works by identifying cells with elevated levels of calcium, which rushes into neurons when they fire. Her team injected mice with genetically modified proteins, exposed their brains to a beam of blue light, and recorded their response to a nicotine injection and other external stimuli. In neurons where calcium level was high, this light then drove transcription of an additional protein, this one fluorescent—a “tag” that they could later detect under a microscope. Her team then used RNA sequencing to uncover the specific genes present in the tagged neurons—effectively determining their type.

Kim, now a professor of neuroscience at the University of California, Davis, is refining the technique—known as fast light and calcium-regulated expression—to better understand how brain signaling works at the molecular level. Ultimately, it could help drive the development of more targeted and effective therapeutics.