If you’ve ever tried to film something while moving the camera around, you know just how challenging it can be. Not only does our brain provide an amazing stabilizing system, but it also manages another difficult phenomenon: blinking. Every few seconds, we close our eyes, and for a brief moment, the world goes dark. But we don’t see it that way; from our perspective, there’s no dark moments, everything flows smoothly. So how does that work?
Caspar Schwiedrzik and Sandrin Sudmann, neuroscientists at the German Primate Center and the University Medical Center Göttingen, were studying something called our perceptual memory — how we perceive the world around us, dealing with things like blinking.
If you think about it, it’s not as simple as it seems: not only does our brain skip the dark moment, but it also pieces together two disparate moments (before and after the blinking) in a continuous flow. Think of it this way: if your brain would only skip it, you’d have small memory lapses every few seconds.
Schwiedrzik and Sudmann identified a brain area that plays a crucial role in perceptual memory by studying patients suffering from epilepsy. Along with American colleagues, they temporarily implanted electrodes into the patients’ brain, and then subjected them to a simple test.
The test displayed a dot lattice on a screen, and participants were asked to assess whether the lattice had a horizontal or a vertical orientation. After the first round, a second round was carried out, based on the assumption that if both orientations were the same, it was an indication that the subjects used the information from the first round to establish a conclusive percept in the second round.
Researchers also identified where brain activity peaks — the medial prefrontal cortex, an area known for mediating complex decisions.
“Our research shows that the medial prefrontal cortex calibrates current visual information with previously obtained information and thus enables us to perceive the world with more stability, even when we briefly close our eyes to blink,” says Caspar Schwiedrzik, first author of the study and scientists at the German Primate Center and at the University Medical Center Göttingen.
This is not only true for blinking but also for higher cognitive functions.
“Even when we see a facial expression, this information influences the perception of the expression on the next face that we look at,” says Schwiedrzik.
“We were able to show that the prefrontal cortex plays an important role in perception and in context-dependent behavior,” says Schwiedrzik, summarizing the findings of the study.
Now, the researchers say they want to investigate this further, analyzing (among others) the role that confidence in one’s own perception plays in perceptual memory.
Journal Reference: Caspar M. Schwiedrzik et al. Medial prefrontal cortex supports perceptual memory, Current Biology(2018). DOI: 10.1016/j.cub.2018.07.066