Your brain’s visual cortex routinely processes the bits and bytes of raw visual data coming into your eyes through multiple, interconnected regions. However, the details of how this fundamental neurological activity works have eluded scientists until now. A team of University of Chicago researchers discovered a unique population of neurons in your lateral intraparietal (LIP) region that is central to perceiving the combination of color and motion, such as when you track a wide receiver running toward the goal line.

"Our study suggests that this area of the brain brings together information from multiple areas throughout the brain," said Dr. David Freedman, senior author of the new study and associate professor of neurobiology. "It integrates inputs — visual, motor, cognitive inputs related to memory and decision making — and represents them in a way that helps solve the task at hand."

Basic information on motion and color are known to route through two regions in your visual cortex, yet how your brain combines these separate streams into a cohesive picture, usable to your decision-making process, has mystified scientists. To investigate this matter, Freedman and Dr. Guilhem Ibos, a postdoctoral fellow, used brain imaging technology to study the response of individual neurons in the brains of monkeys while they performed a simple task.

The experiment worked like this: First, the monkeys saw either a group of red dots moving upward or yellow dots moving downward. Then, the monkeys viewed a series of images composed of different colors of dots moving in different directions. If they released a lever when the first image they saw reappeared, the monkeys received a reward.

While the monkeys performed this task, Freedman and Ibos focused on neurons in the lateral intraparietal area, a region interconnected with brain areas involved in vision, motor control, and cognitive function. They observed how LIP neurons became highly active when the monkeys looked for a specific combination of color and motion in order to perform their task. However, the LIP neurons did not respond at all when the monkeys were passively viewing the same images without performing the task.

The team also noted how individual neurons were able to shift their sensitivity to a particular color and particular direction. For instance, when the monkeys looked for red dots moving upward, a neuron would respond strongly to dots moving in directions close to upward motion and colors close to red. When the task was switched to another color and direction, the very same neurons would be more responsive to the new combination of direction and color.

“Most of the objects in any given visual scene are not that important, so how does the brain select or attend to important ones?" Freedman said. "We've zeroed in on an area of the brain that appears central to this process.” While watching your favorite team, think about each player’s visual abilities — physical talent alone does not earn the big bucks.

Source: Freedman D, Ibos G. Dynamic Integration of Task-Relevant Visual Features in Posterior Parietal Cortex. Neuron. 2014.

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