The Laboratory of Behavioral Neurotoxicology explores how our gut microbiota, the microorganisms that live in our intestinal tract, influence social, emotional, and cognitive functioning, especially during early postnatal development. Gut microbes are vital for digestion and immune functioning, but they also produce chemicals that signal to the brain regarding the health and mental status of the host. Some of these signals are hormones or immune factors that travel to the brain in the bloodstream; but others are neural, meaning that the microbes “talk” with the brain through the nerve that connects the brain with the intestinal tract, the vagus nerve. The brain also “talks” back to gut microbes through the vagus nerve. Communication back and forth between gut and brain is referred to as the “gut-brain axis.”
Gut-brain axis research is revealing that the types of microbes an organism harbors in its digestive tract, its “gut microbiome,” influences anxiety, depression, and social behavior. The gut microbiome is individually unique and highly sensitive to diet, geography, and stress. For young organisms, gut dysbiosis, or an unhealthy gut, can contribute to social, emotional and cognitive problems throughout the lifespan. Intervening in the early postnatal period by enriching the gut with probiotics (bacteria that are conducive to good health) has the potential to mitigate some of these problems.
In our lab, CC students explore how the gut-brain axis influences brain development by studying it in rats. Probiotic supplements, such as those found in yogurt or capsules, improve gut health in rats, as they do in humans. We supplement rat pups (young rats that are equivalent in age to human toddlers) with specific probiotic strains and measure the effects of the probiotics on anxiety, depression, social interaction, learning, and attention when the rats become young adults. Our tests are carefully designed to assess these and many other behaviors that depend upon functioning of specific brain systems.
Students also explore how much the influence of early probiotic treatment is due to direct neural signaling via the vagus nerve. Very little is known about what neural signals from microbes “tell” the brain, and how much influence those signals have. Before probiotic treatment begins, the students perform a surgery on each rat. In half of the rats, the vagus nerve is located and cut at the level of the stomach; in the other half, the nerve is left intact. The surgery, called a subdiaphragmatic vagotomy, has little to no clinical effect on the rats, but it eliminates direct signals between the gut and the brain. The students compare the effects of the probiotic supplementation in rats with and without the vagus nerve.
This research takes place entirely during the summer, so that students can turn all their time and effort toward learning the techniques used in the laboratory. As a team, the students learn and practice surgical techniques, behavioral testing, and histology. They analyze the data we collect, and over the subsequent school year, each student writes a thesis that can qualify them to graduate with Distinction in Neuroscience.
In its 14 years of operation, 31 students have completed research projects in the laboratory. These students have subsequently become M.D.s, Ph.Ds, data scientists, and clinical psychologists. The experience of conducting, analyzing, and communicating original scientific research provided them with an incredible advantage in their graduate and professional studies.
Unfortunately, it is becoming increasingly difficult to secure funding for scientific research, particularly for smaller labs such as ours. Colorado College students have the intellect and the drive to lead future generations of scientists, clinicians, and policy makers. In-depth, hands-on research will give them the tools they need to meet their goals. Please help us continue this vital service to our students!