On the next leg of our sabbatical tour, we stopped through Chicago for the Society for Neuroscience (SfN) Annual Meeting. Two recent Skidmore alums, including Tommy from my lab, earned travel awards from the Faculty for Undergraduate Neuroscience (FUN) to present their research, and it was a privilege to see our relatively young Neuroscience Program represented so strongly. Meeting new FUN faculty and student members while volunteering at the group’s Exhibitor Booth turned out to be another highlight—the kind of service that makes this job much more fun.
SfN is one of the largest scientific conferences in the US (7th in health-related fields as of 2012), and hosted nearly 30,000 attendees this year. The breadth of intersecting disciplines in neuroscience can make for an overwhelming experience. But to focus on a single bright point, Charles Zuker’s Grass Lecture (funded by EEG developers Albert and Ellen Grass) was the kind of skilled, stimulating seminar I always hope to see.
Credit: HHMI: Charles S Zuker, PhD
Zuker’s talk—Receptors, Neurons, and Circuits: The Biology of Mammalian Taste—highlighted the complex, ingrained behaviors linked to the supposed least relevant of the five senses. He outlined extensive evidence that mammals pursue certain tastes (e.g. sweet), but avoid others (e.g. bitter), even at early stages of life—an evidently innate, rather than learned, response. Aversion to bitter taste may be particularly subject to evolutionary pressure: frogs express over fifty bitter receptor genes, possibly to accommodate the wide range of toxins encountered in amphibious life (the homebody chicken, in contrast, has only three). Other tastes, such as salt, are more complex: low levels attract, while higher concentrations repel. Zuker’s group demonstrated in 2013 that high salt activates aversive bitter and sour in addition to salt receptors, a likely survival response to avoid dehydration.
Zuker and others have identified deep brain regions involved in innate taste behaviors, which can be driven by electrical or photostimulation in place of the taste itself. In 2011 his group published a gustotopic map linking specific taste receptors to different regions of the brain. Zuker’s lab is also dissecting neural circuitry underlying thirst, which influences taste in order to balance an organism’s salt and water intake.
Increasing clarity on the neuroscience of taste carries some surprising clinical implications. A unique crowdsourcing study last year linked the supertaster phenomenon to a specific bitter receptor gene (rather than the density of an individual’s taste buds); this year, variations in this gene were shown to predict certain respiratory infections, and could prove to be useful diagnostics.
Chemical signals (such as tumor necrosis factor) associated with infection and inflammation can also increase sensitivity to bitter taste; treating this phenomenon at the molecular level could improve quality of life and longterm outcomes for patients with chronic illness. And receptors for stress hormones have been found in taste cells tuned to sweet, bitter, and umami, suggesting new ways stress may hamper healthy eating and metabolism.
Credit: Livescience.com: Nontaster, supertaster
For me, Zuker’s eloquent lecture tied together several anecdotal experiences of our sabbatical side project: exploring the cocktail culture of each new place we travel. The wide range of preferences in beer, wine, and spirits is particularly intriguing for a substance (alcohol) most people find intrinsically unpalatable—yet learn to enjoy, or even crave, given the right circumstances. And although the neurological basis for drinking will take some time to unravel, a role for environment is clear. One tantalizing example: when we first met, Oliver and I bonded over our shared passion for Bloody Marys—but mostly on planes. It seems our shared penchant was no coincidence, as Cornell food scientists reported this May that loud noises—such as the background roar of an airplane engine—inhibit sweet sensations while augmenting umami, the savory flavor of meat, mushrooms…and tomatoes. Work like Zuker’s could provide a molecular basis for such colloquial, as well as clinical, experiences of taste.
Credit: Vinepair.com: In-flight Bloody Mary
Top credit: FulcrumGallery.com