For this week's #TraineeTuesday (X, Bluesky), we’re spotlighting Calvin Fang, an MD-PhD student at Yale who recently succeeded in defending his dissertation, finishing his PhD! While he is still working on finalizing his publication, closing his lab work, Calvin has traded microscopes for stethoscopes as he resumes his clinical journey.
Calvin’s doctoral research focused on a special group of brain cells called inhibitory interneurons, which control how other brain cells send signals. He observed these cells in the neocortex, the part of the brain involved in higher-order functions such as cognition, sensory perception, and decision-making.
Different types of inhibitory interneurons influence the strength and timing of sensory responses, adjusting how much the brain reacts to signals depending on whether an animal is alert, resting, or engaged in a task. To study these neurons, Calvin used a combination of advanced techniques — including in vivo calcium imaging to watch neurons in action, optogenetics to control them with light, and genetic tools to target specific cell types. A particular focus of his research was on how inhibitory neurons interact with each other, not just with excitatory cells, offering insights into how the brain maintains a precisely tuned balance of activity.
It was incredibly exciting to see my first calcium imaging recordings working properly and watch neurons light up in response to neural activity.
At Yale, Calvin conducted his PhD research in the lab of Jessica Cardin, PhD, where he combined systems-level approaches with a strong foundation in cellular neuroscience. His journey into the field began at Cornell as an undergraduate, where he analyzed extracellular recordings of rodent behavior. However, it was during a postbaccalaureate year at the National Institutes of Health (NIH) in Bethesda that his interest in inhibitory circuits truly took figure. There, he learned how to record electrical signals from individual hippocampal neurons using patch-clamp electrophysiology, a technique that allowed him to observe how single cells communicate within the brain.
I really got interested in the diversity of inhibition and how it shapes activity, so my goal was to pursue a PhD taking what I had learned in Bethesda but begin approaching it again in an awake/behaving system. This is what led me to Dr. Cardin, who shared these interests and was someone my prior lab recommended I should reach out to.
Despite having been immersed in research, Calvin stayed closely connected to clinical care. He volunteered with community health efforts, including participating in the Chemical Abuse Services Agency’s initiatives and a street psychiatry elective. These experiences helped shape his broader interest in mental health care delivery, especially in community-based settings where access and outreach are critical.
As he returns to clinical rotations, Calvin is looking ahead with curiosity and an open mind. While a recent neurosurgery rotation sparked his interest in targeted, circuit-based therapies, his organizational experience draws him to fields like public health and epidemiology.
I think I’ll start to hone those interests more once I’m in a residency program.
Although transitioning back into medical school has felt fast-paced, Calvin is excited for what is to come. As the first in his family to pursue a scientific career, he sees the PhD not as the end of a chapter, but as a foundation for future paths — whether in the lab, the clinic, or somewhere in between.