Dr. Susana Lima
Professor & Principal Investigator, Champalimaud Centre for the Unknown, Lisbon
Postdoctoral Fellow, Cold Spring Harbor Labratory
PhD, Memorial Sloan-Kettering Cancer Center and Yale University
Dr. Susana Lima's career trajectory strikes an endearing balance of science and kismet. Her story could be a romantic comedy featuring a truly impressive woman scientist earning accolades for her experimental ingenuity and falling in love along the way. Susana is now a PI at the Champalimaud Foundation in Lima, Portugal, where she studies the neural circuitry underlying sexual behavior and decision making in female mice.
Susana loved biology from a young age but didn’t know exactly what she wanted to do with this interest in university. She chose to major in biochemistry to keep her options open. Her interest in biology persisted and she decided to do a masters in Biochemistry studying yeast, where she discovered that she enjoyed the process of research and decided to pursue a PhD. However, Susana was once again uncertain what she wanted to do her research in and did not want to limit her options.
She applied to and was accepted to a PhD program in Portugal at the Gulbenkian Institute for Science in general biology. This program allowed her to explore a wide array of topics; she had classes in everything from bioinformatics to evolution. She decided to take one neuroscience course that an upper-level student in the program had recently introduced. This class was Susana’s first exposure to neuroscience, and she immediately knew she’d found what she wanted to study.
After her first year taking graduate classes in Portugal, Susana went abroad to Dr. Gero Miesenböck’s lab in New York City at Memorial Sloan Kettering to do her PhD research (still through the Portuguese PhD program). In her first meeting with him, Gero introduced Susana to the project that would become her dissertation work. Susana was tasked with developing a system to activate olfactory receptor neurons in the fly brain using light. This would be the first published demonstration of the successful use of optogenetics, a field which has since revolutionized systems neuroscience for its ability to selectively activate certain neurons with high spatial and temporal precision.
They planned to do this by expressing drosophila photoreceptor genes, normally present in the eye, in the fly olfactory neurons. This would in essence lead to the activation of olfactory receptor neurons upon light activation. The first four years of her PhD were incredibly challenging -- Susana was able to successfully get the necessary proteins to express in the fly brain but couldn’t induce neuronal activity with light. Susana was convinced her scientific career was doomed, and she would struggle to find a post-doc. However, after four years of optimization, she was finally able to demonstrate in fly neurons that they could induce neuronal activity using light. Susana described her first “Aha!” moment four years into her PhD: using a different strategy, by expressing a rat channel called P2X2 (an ATP receptor) in flies and using an ATP that was only biologically active upon exposure to light, she made flies fly with brief flashes of light. Shortly after this, she published the first paper describing an optogenetics system, a groundbreaking paper that would help lead to the development of the field of optogenetics that dominates systems neuroscience today.
After her PhD, she joined the lab of Dr. Tony Zador at Cold Spring Harbor, a primarily computational lab that was looking for someone who wanted to serve as an interface between wet lab and dry lab techniques. Susana fit the bill. She began a project working on developing a technique tagging neuronal populations for identification during in vivo electrophysiological recordings. The method was based on expressing the light-activated channel channelrhodopsin-2 (ChR2) to restricted neuronal subpopulations. ChR2-tagged neurons can then be detected electrophysiologically in vivo since their illumination with a brief flash of blue light triggers a short latency reliable action potential.
Susana infected neurons with a retrogradely travelling virus that expressed ChR2 fused to green fluorescent protein on one side of the brain, and then looked for expression of the fluorescent protein tagged neurons on the other side of the brain, which would suggest the viral infection was working. She finally got one neuron to express the virus and respond to light, and went to Cosyne, an annual neuroscience conference, with a poster with N=1 (one neuron on it). Six months later, Susana got her second neuron that expressed ChR2 and would respond to light. She developed the technique further and was able to successfully get specific cells of interest to express the virus and respond to light. Susana published her successful development of the technique and completed her post-doc in three years.
At the same time as her post-doc, Susana also met her husband, Dr. Zach Mainen, who had his own lab that neighbored Tony’s. They began dating in August and got married in September, sending a building-wide email telling everyone to come celebrate their wedding. Very few people showed up to the celebration as they thought it was a joke (no one knew Susana and Zach were together). Susana’s whirlwind romance with Zach served as a bit of inspiration for what she wanted to study in her own lab; she wanted to know what factors played into mate selection. Therefore, when Zach coincidentally got an offer to move to Portugal and help start the Champalimaud Neuroscience Programme, Susana eventually also moved back to her home country to start her lab at the same institute, where she chose to study mate selection.
Unfortunately, she found that the mouse models in the lab did not have enough diversity to study mate selection; all the mice were too similar for her to answer the questions she was interested in. To study mate selection, her lab was running experiments in which they put a male and female mouse together and watched their decision making and behavior surrounding copulation. However, Susana’s experience running these experiments piqued her interest in female sexual behavior. The lab carefully investigates sexual behavior, and then looks at how this behavior involves brain regions such as the hypothalamus using imaging and electrophysiological methods. Generally, the lab is focused on understanding the interplay between sex hormones, behavior, and neural circuits in mice during mate choice and sexual behavior.
Susana’s trajectory, it seems, bears one more hallmark of the rom-com genre; the happy ending and promise of a bright future. Susana’s love of science and the scientific process suffuses through her voice. Her unfettered passion and curiosity guided her through a very challenging PhD and post-doc project. Now, with her work on mate selection, arguably the focus of every romantic comedy, her talents and enthusiasm are sure to lead to a bright future for her and her mentees.
Find out more about Susana and her lab’s research here.
Listen to Meenakshi’s full interview with Susana on May 23, 2025 below!
