Sense and Sensibility
by Lindsay Borthwick
When it comes to taste perception, mosquitoes don’t follow the same neural code as most other organisms
The Author
The Researchers
Not a month goes by that long-held assumptions about the brain and nervous system aren’t proven wrong. For example, a lab at The Rockefeller University, home of the Kavli Neural Systems Institute, found when it comes to taste perception, mosquitoes don’t follow the same neural code as most other organisms. Working instead in mammals, a research team from the Kavli Institute for Brain and Mind at the Salk Institute showed that spontaneous brain waves, long thought to be an artefact of anesthesia, sharpen our sense of vision, allowing us to see objects we might otherwise overlook. Those are just two of the research highlights in this month’s round up, which ends with a pair of non-fiction books penned by two Kavli-affiliated neuroscientists. One illuminates the fascinating collective behavior of army ants; the other delves into the roots of intelligence and where artificial intelligence is headed.
Blood Meal
The mosquito is slowly yielding its secrets to Leslie Vosshall, PhD, director of the Kavli Neural Systems Institute and her research team. In a study published this month in Neuron, they identified the specific neurons in the mosquito’s skin-piercing stylet that respond to the taste of blood. They also pinpointed the array of different compounds in the blood that activate those cells. “These neurons break the rules of traditional taste coding, thought to be conserved from flies to humans,” said Veronica Jové, the graduate student in Vosshall’s lab who led the study. “We knew that the female stylet was unique, but nobody had ever asked what its neurons like to taste.” The new research builds on previous findings from Vosshall’s lab about the insect’s sensory system, including an odorant receptor that mosquitoes use to distinguish between humans and non-humans. By harnessing this new knowledge about the mosquito’s sense of taste, researchers may be able to design ways to stop the insects from biting humans and spreading deadly diseases.
Wavy Vision
Traveling brain waves help us perceive objects that are faint or otherwise difficult to see, according to new research from researchers at the Salk Institute and the Kavli Institute for Brain and Mind. “It turns out that these traveling brain waves are an information-gathering process leading to the perception of an object,” said John Reynolds, PhD, who led the new research published in Nature this month. Brain waves have been recorded during anaesthesia, but it was unclear whether they played a role in active vision. The researchers found that these spontaneous neural signals enhanced perceptual sensitivity, and also that the brain’s ability to recognize objects was directly related to when and where the brain waves occurred in the visual system. The research raises the question, do these waves serve as a gate between sensory processing and conscious perception in the brain as a whole?
Love in Moderation
One of the common characteristics of autism is impaired social behaviors: People with autism often struggle to form friendships yet they do form close bonds with family members. Now, a new study from the lab of Gül Dölen, MD, PhD, at Johns Hopkins University, helps explain why. In experiments in mice, the researchers showed that these two types of affection are encoded by different types of oxytocin neurons. One cell type, parvocellular oxytocin neurons, encode behaviors associated with what Dölen terms “love in moderation,” or the love we feel toward members of our community. They are smaller and rarer than another oxytocin-producing neuron, magnocellular neurons, and they release far less of the neurotransmitter when active. Gölen, working with neuroscientist Loyal Goff, characterized the two types of cells using single-cell sequencing, then in a series of gene-silencing experiments, studied the impact of the two cell types on social behavior. Gölen’s research has implications for the treatment of autism. Trials of intranasal oxytocin have had mixed results, which she said may be because the treatment is targeting the wrong cells: magnocellular instead of parvocellular neurons. Both Goff and Dölen are members of the Kavli Neuroscience Discovery Institute.
Alternative Fuel
Yale’s Tamas Horvath, DVM, PhD, has spent decades trying to understand what drives hunger. His latest paper looks at the role of a type of neuron that is active during food restriction, hypothalamic agouti-related peptide (AgRP), in anorexia nervosa, a psychiatric disorder that can be fatal. In experiments in mice, Horvath and his team found that inhibiting AgRP neurons in mice on a food-restricted, high-exercise diet proved fatal, likely because those neurons help the body access alternative sources of fuel like fat. When their activity level of AgRP neurons dropped, the animals were unable to access fat stores. But the team could prevent the animals’ death by supplying high-fat foods—a finding that could help with the treatment for people dying of anorexia, said Horvath. They are now working to identify which fats may work best. “Many people with this disorder are in the care of medical professionals, and there’s an opportunity to bring these findings to the human population,” he said.
Neuro Book Club
This month, Kavli NSI’s Daniel Kronauer, PhD, head of Laboratory of Social Evolution and Behavior at The Rockefeller University, published Army Ants: Nature’s Ultimate Social Hunters (Harvard University Press). The book contains more than 100 photographs of the ants, which Kronauer calls “the obvious superstars of the tropical ant world” in a recent Q&A. Many of the stunning images were shot during fieldwork by Kronauer, whose earned a Wildlife Photographer of the Year award in 2019.
Also out now is the Birth of Intelligence (Oxford University Press) by Daeyeol Lee, PhD, whose research is focused on decision making and higher-level cognition. In a recent Q&A about the book, which traces the biological roots of intelligence and the limits of intelligence, Lee takes on the question of whether artificial intelligence will ever surpass human intelligence: “In my view... true intelligence requires life, which can be defined as a process of self-replication. Therefore, I believe that superintelligence is either impossible or something in a very distant future.” Lee is the Bloomberg Distinguished Professor of Neuroeconomics at Hopkins and a member of the Kavli Neuroscience Discovery Institute. For many years, he held a faculty position at Yale University, where he was a member of the Kavli Institute for Neuroscience.