Dr. Maria Diehl
Assistant Professor of Psychological Sciences Kansas State University
Postdoctoral Fellow University of Puerto Rico
PhD in Neuroscience University of Rochester
When she was in 8th grade, Dr. Maria Diehl’s curiosity drove her to a defining moment. During a fetal pig dissection in biology class, Maria first followed her teacher’s instructions, identifying different organ systems in the chest and abdomen. But then Maria decided to stray from the directions and opened the skull to sneak a peek at the brain. From then on, she was hooked. She knew she wanted to spend her career doing something brain related. Today, Maria is an assistant professor in the Department of Psychological Sciences at Kansas State University. Her lab studies adaptive behaviors and the neural circuits underlying them.
Still enamored with the brain when she entered Emory as an undergraduate, Maria was drawn to the neuroscience and behavioral biology major, an interdisciplinary program that combined psychology, anthropology, and biology. While it had been love at first sight with the brain, Maria originally had her gaze set on medical school rather than a research career. She soon realized, however, that she did not feel at home with the pre-med “vibe” and shifted her attention to neuroscience itself, which eventually led to an interest in research. After a brief experience in a psychology lab, she joined a monkey lab studying sex differences in cognitive aging. While running behavioral tasks and even some MRI scans on the monkeys, Maria felt as if she had finally found her niche.
Despite a positive undergraduate research experience, imposter syndrome kicked in when Maria considered applying to graduate school. She wasn’t sure that she could get in or succeed once there. To better prepare herself, Maria entered a post-bacc program at Virginia Tech. Having become interested in the evolution of language during undergrad, she joined a lab studying language development in infants. While she found the research questions interesting, the experience made it clear to Maria that she preferred working more directly with the brain than is possible with human subjects. Thus, after being accepted into the neuroscience graduate program at the University of Rochester, Maria chose the lab of Dr. Liz Romanski, where she studied audiovisual integration of vocalizations and faces in rhesus monkeys. Maria recorded from a monkey’s cortex while showing a video of another monkey making a call. The facial expressions and call types in the video were modulated such that the stimuli were matching (e.g. a “coo” sound with a friendly face) or mismatching (e.g. an aggressive call with a friendly face). Maria discovered that there are neurons in the ventrolateral prefrontal cortex that not only respond to both faces and voices but that change their firing rate based on whether the stimuli are matched vs. mismatched. These data helped to confirm the importance of the ventrolateral prefrontal cortex in integrating faces and voices, potentially playing a key role in social communication.
As the years of her PhD progressed, Maria began to realize that she wanted to move away from studying monkeys for her next research endeavor. While she enjoyed working with them, she saw the limitations of investing so much time and money into only a couple individual animals. Maria also knew that she wanted to be able to mentor undergraduates when she had a lab of her own, which is difficult to do in a monkey lab. She eventually found the environment she was looking for in the lab of Dr. Greg Quirk at the University of Puerto Rico. When she visited the lab, the warm welcome she received from the other trainees made Maria feel immediately at home. Although learning to design experiments for rats was a bigger learning curve than she expected, Maria soon settled into a groove. For her postdoc, she worked with a fear avoidance paradigm. Rats were trained to associate a tone with a foot shock but were given a platform where they could escape the shock. The caveat? From the safety platform, the rats could not reach the lever that they press for food. The paradigm therefore simulates avoidance behavior and how it might interfere with other strong motivations. Maria used optogenetics to silence different parts of the avoidance circuitry while recording from prelimbic cortex. She then used the information from this experiment to manipulate prelimbic projections to the basolateral amygdala and ventral striatum. Interestingly, she found that silencing prelimbic projections to the amygdala delayed the rats’ escape to the safety platform, whereas silencing prelimbic projections to ventral striatum hastened this behavior. Modulation of prelimbic activity therefore enables an animal to make decisions in contexts of competing motivations (e.g., shock avoidance and food reward).
After a successful postdoc, Maria accepted a job offer at Kansas State University. However, the early days of her lab presented many challenges. She started her lab in the middle of the COVID-19 pandemic, which meant that several important items were backordered and slowed early progress. It also meant that her earliest trainees were struggling through social isolation and did not have the motivation and sense of camaraderie that can come from feeling a part of a lab community. On top of this, Maria gave birth to her first child around the same time and had to mentor from afar while on maternity leave. Although the beginning was rough, Maria and her lab pulled through these challenges, and the lab is now beginning to grow. As she hires more trainees, though, Maria’s main goal remains the same: to get people excited about neuroscience.
In her lab, Maria is building off her postdoc work. She is using a similar avoidance paradigm but has modified it to study social interactions in the context of avoidance behavior. She is interested in understanding how the behavior of the rats might be altered if two rats are experiencing the paradigm together. Will they learn from each other? What if one of them has experience with the task prior to being put with another rat? Will that change how the naïve rat learns avoidance behavior? As she works to answer these questions, Maria’s innate curiosity for the brain will undoubtedly inspire her young trainees. And perhaps when they see a rat brain for the first time, they will feel as Maria did back in 8th grade—a magical, aha moment that makes them want to spend their life studying the brain and its mysteries.
Find out more about Maria and her lab’s research here.
Listen to Nancy’s full interview with Maria on August 19th, 2022 below!
