The senses are everything, says Stanford University neurobiologist Tirin Moore: “They are your interface with the world.” Since junior high, Moore has been intrigued by how our brains interpret the information that comes in via the senses, an interest he explored through filmmaking and cartooning as a child. “That interest just became a bit more scientific as I became curious about how we decide what is actually out there.”
Moore has made major strides in understanding how the brain selects which items, among the overwhelming number contained in a scene, to pay attention to. “Vision is very much the dominant sense for humans,” he says. “Understanding it—of all senses—is perhaps the best way to understand how the human brain extracts information from the environment to guide behavior.”
While the importance of selective attention is understood by anyone who has ever tried to juggle, the neural mechanisms behind it are quite mysterious. Moore wants to understand the phenomenon at the level of individual neurons and neural circuits. “Some mechanism is selecting, from among all those neural signals, the ones that should drive behavior. That’s the level at which I’d like to be able to explain attention,” he says.
So far, his work has revealed some important connections between the visual cortex—where visual information is processed in the brain—and higher cognitive functions, including attention. An area in the front section of the primate brain, called the frontal eye field, contains neurons that control eye movement. Moore discovered that these neurons play another, previously unknown role. When the neurons in the frontal eye fields are activated in the brains of rhesus monkeys, the animals pay closer attention to certain visual stimuli.
Moore concluded that these frontal eye field neurons have both motor and visual functions. “Just by deciding to move your eyes to look at a certain area in front of you, you can essentially raise the volume on the strength of signals coming from that part of space,” Moore says. Those signals become more important than competing signals coming in from other areas in the visual field. “That seems to be the trick the brain plays to allow you to selectively attend to locations in space.”
Though scientists have speculated about this phenomenon for nearly a century, Moore was the first to demonstrate the neural mechanism behind it. “Before that [study], we had no idea what was causing attention. These results really moved us into a different gear in which we could actually say something about what is causing these cognitive functions,” Moore says.
Moore plans to expand on this research with studies on the relationship between short-term memory and attention. While it’s known that you can’t keep something in short-term memory without paying attention to it, “we don’t understand the connection between the two at the level of neural circuitry,” Moore says.
He also hopes his research will help determine how the neural circuitry of attention fails in people who have attention deficit hyperactivity disorder. “If you figure out the mechanism that determines which items you process from the visual environment, then you should be able to understand how things might go awry when that mechanism fails,” he says.