Columbia University neuroscientists discovered our brains send sensory information to two independent regions, completely changing the way we believe our brain processes key functions like sight, sound, and decision-making. Researchers used rat whiskers, which operate much like human fingers, to study the flow and destinations of sensory signals. It was previously believed that when you do something like touch a tennis racket, that sense’s signal was processed through the brain’s thalamus (the “middle man”) and distributed to the six layers of your brain’s cortex in a serial fashion—much like a computer. Now, we know once it passes the thalamus it runs in two major loops—one running to the deep half of the cortex and below, and another running to the upper half of the cortex and its layers. “These are probably not redundant systems,” says researcher Randy Bruno, PhD, assistant professor in the department of neuroscience at Columbia University. “The ‘top brain’ and ‘bottom brain’ almost certainly have different functions.” The upper half of the cortex has become thicker with evolution—thinnest in mice, thicker in a monkey, but thickest in humans. “If the upper layers were, in fact, a generalized learning machine, it might explain why humans are better problem solvers than monkeys, and monkeys better than mice,” he suggests. “Many scientists thought these sparse connections into the deep half of the cortex were wiring mistakes,” says Dr. Bruno. Not only are they intentional, they’re completely uninterested in what’s happening up above. When Bruno used a localized anesthesia to shut down different levels of the cortex, the activity in the deepest layer continued to receive and transmit signals. Finding out for sure is his and his fellow researchers’ next step: training animals to perform different tasks to find out what happens when you switch a specific layer off. “Because the two halves connects to different parts of the brain, we may find someday that specific psychiatric disorders involve disruptions of one half versus the other,” says Bruno. Someday, however, is the key.
