Imagine that you're late for work and desperately searching for your car keys. You've looked all over the house but cannot seem to find them anywhere. All of a sudden you realize your keys have been sitting right in front of you the entire time.
Why didn't you see them until now? Now, a team of Salk Institute scientists led by Professor John Reynolds has uncovered details of the neural mechanisms underlying the perception of objects. They found that patterns of neural signals, called traveling brain waves, exist in the visual system of the awake brain and are organized to allow the brain to perceive objects.
The waves actually facilitate perceptual sensitivity, so there are moments in time when you can see things that you otherwise could not. It turns out that these traveling brain waves are an information-gathering process leading to the perception of an object.
Scientists have studied traveling brain waves during anesthesia but dismissed the waves as an artifact of the anesthesia. Reynolds' team, however, wondered if these waves exist in the visual part of the brain while awake and if they play a role in perception. They combined recordings in the visual cortex with cutting-edge computational techniques that enabled them to detect and track traveling brain waves. The findings were published in the journal Nature on October 7, 2020.
The scientists recorded the activity of the neurons from an area of the brain that contained a complete map of the visual world. They then tracked the trajectories of the traveling brain waves during a visual perception task. The scientists held an onscreen target at the threshold of visibility, and noticed that the target discovery rate improved gradually. They also found that the brain's ability to recognize targets was directly related to when and where the traveling brain waves occurred in the visual system: when the traveling waves aligned with the stimulus (like when an individual's wants to find something important related to a work appointment), the observer could detect the target more easily.
"We go about our everyday lives thinking that we are accurately seeing the world, but, in fact, our brains are filling in details that are difficult to see. Now, we have discovered how the brain weaves together hard-to-see information to perceive an object," says Zac Davis, co-author of the paper in a report published on the website of Salk Institute.
