Dr. Carmen Maldonado-Vlaar
Professor University of Puerto Rico, Rio Piedras
Postdoctoral Researcher Scripps Research Institute
PhD Northeastern University
In her high school science class in Puerto Rico, Dr Carmen Maldonado-Vlaar learned not only about science, but also that an exceptional mentor can inspire a sense of belonging. As she went on to become an accomplished neuroscientist and a mentor to others, her appreciation for the power of mentorship has only grown stronger. Now a Professor at the University of Puerto Rico, Rio Piedras, Carmen has made fundamental discoveries of how the brain guides reward learning while becoming one of the most outstanding mentors in our field.
In her undergraduate studies at the University of Puerto Rico (UPR), Carmen decided to major in biology and psychology. She was motivated to combine these two fields by her desire to understand the biological basis of behavior and its dependency on environmental and social contexts. Although she was initially encouraged to pursue a career in medicine, her trajectory changed when she had her first experience working in a neuroscience research lab with Dr. Jose G. Ortiz in the Department of Pharmacology, UPR-Medical Sciences Campus. Carmen studied the cognitive effects of GABA modulation in seizure models in mice. This led to two publications, effectively launching her career as a neuroscientist. Being able to significantly contribute to science at such an early stage of her academic career gave Carmen the confidence to continue pursuing research. “[Those] feelings of belonging were instrumental for me to carve my way up to where I am now.” Toward the end of her undergraduate degree, Carmen participated in an exchange program at the University of Massachusetts, Amherst to learn more about college life and the cultural landscape for a young Latina on the mainland. She enjoyed her experience so much that she decided to return for a gap year to do more neuroscience research after she graduated from UPR.
While Carmen was in Boston, she began to think about opportunities for graduate school. At the time, graduate information was not available online, so she visited the psychology department at a prestigious university seeking information. Disturbingly, the chair of the department told her that opportunities for the research she was interested in were limited at that institution, an answer which, in retrospect, was an omen of the prohibitive state of the research landscape for underrepresented minorities. In stark contrast to that experience, Carmen was actively recruited by Northeastern University: the chair of their Psychology department called her directly to invite her for a campus visit. Encouraged by the welcoming and diverse culture at Northeastern, Carmen began a masters degree with Dr. James Stellar, the department chair who had called her. At the time, she was the first Latina and the first Puertoriqueña to be admitted into the graduate program. While the immediate culture around her was welcoming, Boston in the 1980s was a different story. “I felt like a fly in a glass of milk,” she reflects when describing feeling ultra-visible in a city that was— to a degree — ethnically siloed.
Persevering through experiences of discrimination outside the lab, Carmen finished her masters degree in the Stellar lab. She learned the technique of intracranial self-stimulation in rats, a model in which rats press a lever to electrically stimulate reward centers in their brain. She observed that administering a cocaine analog increased the amount of self-stimulating lever pressing, suggesting that the more drug a rat received, the more stimulation was required to achieve the same pleasurable effect. After completing her masters, Carmen moved on to her PhD research in the lab of Dr. Anne E. Kelly, where she continued to investigate the neural underpinnings of reward learning in a small neural structure called the nucleus accumbens (NAc). Anatomists had separated the NAc into two subparts, the core and the shell, but little research had been done to show if or how these subsections were responsible for different behaviors. Using precise pharmacological microinjections to independently decrease neural activity in the core and shell of the NAc, Carmen discovered that the core and shell have distinct behavioral profiles in rats. The core was responsible for motor responses, while neurons in the shell drove limbic, emotional responses. This research, which Carmen conducted in the mid 1990s, formed the basis of our understanding of the functional heterogeneity of the NAc and guides investigations of its neurobiology to this day.
After her PhD, Carmen wanted to continue learning about self-administration reward behaviors and joined the lab of Dr. George Koob at Scripps Research as one of 30 postdocs. She worked with his collaborator, Dr. Bert Weiss, and fellow postdoc, Dr. Larry Parsons, to develop a highly influential behavioral paradigm of addictive behaviors. In this paradigm, rats are conditioned to self-administer cocaine via a lever-press in an environment with specific auditory and visual cues associated with the rewarding behavior. Once learned, the rats were removed from the environment and the behavior was extinguished. This behavioral extinction often took several weeks due to the highly addictive nature of cocaine. But when the rats were then placed back into the same environmental context of the addictive behavior, they went back to lever-pressing even when no cocaine was delivered. Much like human drug addicts who, after detox, relapse when they return to environments connected with drug-use, the rats exhibited the same context sensitivity in their self-administration of cocaine. This finding was groundbreaking, shaped addiction research in animals, and led to the development of therapeutic interventions for drug relapse prevention in humans.
For the last 27 years, Carmen has been running her lab at the University of Puerto Rico, Rio Piedras as a principal investigator and Professor of neuroscience in the Department of Biology. She has continued to study reward learning and the multitude of factors that affect addiction and reward behaviors in brain structures like the NAc. She also studies the role of neurotransmitters, neuromodulators, and hormones like oxytocin and how they can be used to treat the painful feelings associated with withdrawal from addictive substances like cocaine. Going forward, she hopes to explore the role of the endocannabinoid system in the neurobiology of reward learning and looks forward to the promising future of cannabis research once federal restrictions are reassessed.
In addition to her lab’s research, Carmen is a proud advocate for effective mentorship and the fundamental need to establish and nurture diversity in science. As the Director of Undergraduate Research and proud mentor to over 100 Hispanic & Latine students, 70% of whom are women, Carmen continues the tradition of compassionate, supportive mentorship. In recognition of her devotion to uplifting the next generation of scientists, Carmen received the Bernice Grafstein Award for Outstanding Accomplishments in Mentoring from the Society for Neuroscience. While the cultural trend of demonizing DEI efforts is frustrating, Carmen is committed to fighting for her and her students’ right to be in the room. Carmen stands up for diversity and inclusion in science by consistently showing up and speaking out against discrimination in any form. She’s not afraid of creating a little “good trouble” to make sure the world knows that scientists of all backgrounds are here to stay, and the world will only be better for it.
Listen to Nancy’s full interview with Carmen on January 25th below!
