Dr. Silvana Valtcheva
Junior Group Leader University of Cologne
Postdoctoral Fellow New York University School of Medicine
PhD in Neuroscience Pierre and Marie Curie University
Growing up in post-communist Bulgaria, young Dr. Silvana Valtcheva found her love for science outside of the classroom. Without any formal, hands-on science education, as her country was struggling to transition into a democracy, Silvana found scientific stimulation playing around her native city of Sofia. She would follow around the cockroaches and other bugs that sought refuge in the pavement cracks, making notes about their breeding patterns, eating habits, movements, and other behaviors. Later on, she developed a keen interest in pharmacology and chemistry and started reading (for fun) some of the pharmacology books that her mother, a pharmacist, had around the house. Despite having no real introduction to laboratory research, these early, self-driven research endeavors instilled in Silvana a deep passion for biological research, which she was determined to pursue abroad. That intense drive has taken her from Bulgaria to Paris to New York City and now to Germany, where she has just started her own lab studying maternal physiology and synaptic plasticity at the University of Cologne.
Silvana’s first introduction to neuroscience didn’t come about until late in her undergraduate training at the Pierre and Marie Curie University in Paris, and she was initially unimpressed. She was unconvinced by the early neuropsychology studies of lesion patients that purported to identify neural substrates of cognition and behavior; without concrete equations to define those relationships, Silvana thought it all sounded like “alchemy”. Fittingly, then, it wasn’t until she learned about the Nernst equation — which defines how electrical and chemical forces determine the flow of ions across neuronal membranes — that her interest was piqued. Finally, upon exposure to the field of synaptic plasticity, Silvana was sold. She was absolutely fascinated that certain patterns of activity can leave different memory traces at the level of the synapse, and particularly that the timing of those activity patterns can control different plasticity rules. She has been studying synaptic plasticity ever since.
Silvana was admitted to the competitive Master’s program in Physiology at the Pierre and Marie Curie University. Although her enthusiasm for research — and by this time, for synaptic plasticity in particular — remained strong, this period of her life proved to be a particularly trying time that put her goal of pursuing a PhD into question. Struggling with mismanaged projects, poor mentorship, and a fair amount of bad luck, her research endeavors were failing, and her grades — which were based primarily on research outcome rather than effort — suffered. Supervisors were telling her that she wasn’t going to be able to get her PhD, and her self-esteem plummeted. Although Silvana describes this as the lowest point of her career, she did not give up. During one such research experience, a particularly generous and supportive postdoc offered to teach Silvana patch clamp electrophysiology to record electrical activity from cultured neurons. Silvana thought that perhaps, even though she was a “bad student”, if she learned how to do one technique really well, that could be her “in” for graduate school. Unfortunately, there was only one rig for doing these experiments, so Silvana did her primary project during the day and then at night when the postdoc was finished with the rig, Silvana would jump on and patch through the night. When she ultimately applied for PhD labs, she had a particularly engaging and inspiring conversation with Dr. Laurent Venance. But to her surprise, when she proudly declared that she knew how to patch, his response was simply, “I don’t care”. At first she was taken aback, thinking that metaphorical door had been slammed right in her face, but he elaborated: “I don’t care about your skills, I care about your motivation”. Finally she had found an advisor who recognized and appreciated her intellect and drive.
In the supportive and intellectually stimulating environment of the Venance Lab, Silvana thrived. She successfully obtained her own funding and quickly started generating exciting data. Her PhD work involved looking at how astrocytes control spike timing-dependent plasticity (STDP) in the striatum. She found that plasticity at the synapses between cortical projections to the striatum were highly sensitive to the amount of glutamate in the synapse, which was carefully regulated by local astrocytes. If she up- or down-regulated astrocytic glutamate transporters that gobble up extra synaptic glutamate, STDP was significantly disrupted or even abolished. In fact, changes in the amount of glutamate reuptake by astrocytes seemed to regulate the types of plasticity that could occur at these synapses — such as whether they cared more about the frequency of input activity or how the input activity temporally aligned to ongoing activity in the striatal neurons (i.e., STDP).
Coming out of her successful PhD and still passionate about patching and plasticity, Silvana set her sights on a singular lab in which she wanted to do a postdoc or else not at all (a strategy she does not recommend to others!). That lab was at the NYU School of Medicine and run by Dr. Robert Froemke, who was using in vivo patch techniques to look at experience-dependent plasticity in living, breathing animals — a logical level up from her previous work looking at activity-dependent plasticity in brain slices. Once she obtained funding to support the first year of her postdoc (with a grant she applied for in a single day!), she officially joined the Froemke lab. Silvana embarked upon an extraordinarily technically challenging project in which she patched from oxytocin-producing neurons deep in a tiny subnucleus of the hypothalamus, all in awake, maternal mice that were listening to recordings of mouse pup vocalizations. She identified a circuit through which vocalizations (but not other sounds) engage plasticity in the hypothalamus that result in prolonged activation of oxytocin neurons and subsequent oxytocin release elsewhere in the brain. Thus, contrary to the prevailing view in the field that oxytocin neurons — most famous for their essential roles in lactation — were merely part of a reflexive circuit for milk ejection, Silvana’s work suggests that oxytocin neurons actively integrate multi-sensory cues, including auditory cues, through mechanisms of plasticity.
Silvana plans to expand upon this exciting work in her newly opened lab at the University of Cologne. Her research program will focus on the pathways and plasticity mechanisms which control the activation of oxytocin cells, oxytocin release, and other aspects of maternal physiology. She also plans to incorporate her interest in astrocytes developed during her PhD, as existing evidence suggests that hypothalamic astrocytes could play an intriguing role in plasticity in the maternal brain. While she has many exciting projects and a clear path in mind, she welcomes that the trainees she recruits to her lab will come in with their own experience and passions that will further shape her lab’s research direction.
When not in the lab, Silvana can likely be found doing aerial acrobatics — a pastime that has been surprisingly formative in her approach to science. “When you’re really high up…often you hang with one hand, upside down, and you really do not have the option to fall! …I tell myself, you can change shape, you can change strategy, but you don’t give up — the show must go on!” She has found this analogy really helpful for pushing through the low points of her scientific journey, as well as for staying nimble and flexible with her research goals as she embarks on her career as a PI. Already Silvana has demonstrated incredible fortitude and fantastic feats in her journey thus far, and the rest of the show is sure to be an amazing one.
Find out more about Silvana and her lab’s research here.
Listen to Megan’s full interview with Silvana on April 13th, 2022 below!
