What’s the colour of the laptop or mobile screen in front of you? Is it white? What if we tell you that it’s not really white? Yes, that’s right. You are being fooled into thinking that you’re seeing the color white. What you are really seeing is lots of red, green, and blue elements packed so tightly together that it gives the impression of being white. Well, that’s the science behind it!We all know about optical illusions; we have seen them. While some may be new, we are surrounded by such illusions. Yet, can’t believe? Okay, let’s try once again. Have you ever seen a fast-rotating wheel or propeller? For a brief moment, have you wondered if it’s running in the reverse direction, while it’s accelerating to full speed? Well, that’s exactly how optical illusions work. They give your mind a challenge, a run for the money. Optical illusions aren’t just fun; they can be useful to understand how eyes, nerves, minds, and brains perceive reality. Here’s one optical illusion for you
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What do you see here? Those winding lines are absolutely confusing your eyes. But beyond that, do you see the neon colour spreading? Not just you, even mice see the neon colour bleeding. Interestingly, this is also the first time research shows that this kind of visual illusion works on mice as well. This study combines the use of two investigative techniques called electrophysiology and optogenetics to study this illusion.This study on mice cleared the long-standing debate in neuroscience about which levels of neurons within the brain are responsible for the perception of brightness. This optical illusion also worked on mice, but why is it important
Pic courtesy: Wikimedia/blebspot CC-0This is a classic neon-color-spreading illusion and is not the same as the one used in these experiments. Chances are you can glance at this and initially see a light-blue circle in slight contrast to the otherwise white background. But in reality, the background is entirely white; it’s as if the blue from the blue sections of the black filaments bleeds into the circle implied by the ends of the blue lines.
Associate Professor Masataka Watanabe from the Department of Systems Innovation at the University of Tokyo is exploring the nature of consciousness. His recent research analyzes whether a certain kind of illusion that works on humans would also work on mice. And it turns out, it does. But why is this significant? “Knowing this kind of illusion, called a neon-color-spreading illusion, works on mice as well as humans, is useful for neuroscientists like myself, as it means that mice can serve as useful test subjects for cases where humans cannot. To really understand what goes on inside the brain during perceptual experiences, we need to use certain methods that we cannot use on people. These include electrophysiology, the recording of neural activity with electrodes, and optogenetics, where light pulses enable or disable firing of specific neurons in a living brain,” Watanabe said.
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This first-of-its-kind experiment used both electrophysiology and optogenetics at the same time in animal test subjects exposed to the neon-color-spreading illusion. This allowed the research team to see precisely what structures within the brain are responsible for processing the illusion. “After a visual stimulus lands on the eye, it’s carried to the brain by nerves and is then received by a series of layers of neurons called V1, V2 and so on, where V1 is the first and most basic layer, and V2 and above are considered higher layers. There is a long-standing debate in neuroscience about the role higher levels play in the perception of brightness, and it was not an easy thing to study. Our experiment on mice has shown us that neurons in V1 responded not just to the illusion, but also to a non-illusory version of the same kind of pattern shown. But only when the illusory version was shown to the mice did neurons in V2 also play a crucial role: that of modulating the activity of neurons in V1, thus proving that V2 neurons do in fact play a role in the perception of brightness,” said Watanabe.
