Paul Forlano and two members of his team at the Aquatic Research and Environmental Assessment Center at Brooklyn College pictured holding an oyster toadfish, another vocal fish and close relative of the midshipman found in the Hudson River, August 2019.
The plainfin midshipman fish is often informally called the California singing fish. Recent research shows that it’s also a very good listener. Studies led by Paul Forlano, associate professor of biology, have demonstrated that the chemical dopamine, which can work as both a hormone and a neurotransmitter in the brain and body, decreases in the female plainfin ear, enabling her to better hear courtship calls from the male of the species. Discoveries made studying this fish may give rise to greater insights into how the hormone works with neuromechanisms in other vocalizing vertebrates.
“It turns out that—like songbirds, frogs, and, of course, humans—certain fish also communicate by sound to attract a mate,” Forlano says. “Midshipman and other toadfishes represent an archetype for how a vertebrate nervous system produces and perceives sounds in a social context.”
Forlano is one of America’s leading authorities on the subject and acknowledges a team effort. “This research, initially funded by the National Institutes of Health, was carried out by many talented Brooklyn College undergraduates, several graduate students, in particular, former Ph.D. student Jonathan Perelmuter, and collaborations with the lab of Joe Sisneros at the University of Washington.” Forlano was subsequently awarded a half-million-dollar grant by the National Science Foundation to support his research project, “Mechanisms of Sound Source Localization Underlying an Ancestral Mode of Vertebrate Hearing.” “Seasonal changes to this circuit in females help their hearing sensitivity grow in the summer mating season, making them better able to hear the males’ mating calls.” It was also a surprise that this tendency did not result from more dopamine but rather less, and fewer receptors in the inner ear during the reproductive season.
It’s not an exaggeration to say that these sorts of studies have been Forlano’s life work. He explains, “My path in science really began as an undergrad when I was given the opportunity to conduct independent research.” His topic was the neurochemistry of the salamander olfactory system. “Importantly, it involved collecting animals in the wild as well as intense labwork, an approach to science I would continue to enjoy for years to come,” he says. “During that early and critical period, I discovered I was quite good at slicing brains into thin sections and visualizing their chemical contents.”
Forlano was an undergraduate at Ursinus College; he earned his M.S. at the Florida Institute of Technology and was awarded a Ph.D. at Cornell University. As a master’s candidate, he was able to employ those newly acquired skills to investigate the brains of stingrays, an animal that had long fascinated him. “I gained a wide appreciation for sensory biology and behavior, as well as neuroanatomy and physiology,” he says, “and was hooked on the ‘neuroecological’ approach of science: studying the brain in the context of an animal’s natural behavior in its natural environment.” It was at Cornell, while working with Professor Andrew Bass, that Forlano turned his attention to the midshipman fish.
In his lab at Brooklyn College, he has focused on “how neuromodulators involved in attention, motivation, and reward—such as dopamine—might interact with circuitry involved in auditory-driven social behavior.” He continues, “Interestingly, some dopamine-producing neurons in the brain send projections to the inner ear, but the function of this circuitry is not well understood; therefore a biological role for dopamine in the inner ear in the context of natural behaviors, such as the detection of socially relevant stimuli, remains unexplored.”
According to Forlano, these results suggest an important role for dopamine in hearing and the behavioral response to social acoustic signals that starts in the inner ear, and the implications extend well beyond aquatic creatures. He says, “By using this simple model, we have uncovered a natural function that has potential broad implications for understanding fundamental mechanisms of acoustic communication in other vocal vertebrates, including ourselves.”