How do you make a mouse hallucinate? (And why would you even try?)
Hyeyoung Shin, PhD, an assistant professor of neuroscience at Seoul National University, turned to mice to help explain what makes one person perceive reality differently from another. Take the great dress debate from 2015, for example, when people across social media argued over whether an online post depicted a white-and-gold or a blue-and-black garment (Spoiler: It was the latter).
Shin herself wondered what her brain was doing when she looked at the dress image online. More than 10 years later, in a study published in Nature Neuroscience, she was finally able to explain why.
In their study, Shin and her colleagues zapped the brains of six mice with ultraprecise holographic lasers, targeting a tiny cluster of cells in the brain’s first layer of image-sensing neurons, an area called V1. Researchers asked whether sparking those cells alone could make the brain “see” something that wasn’t really there.
The animals’ brains lit up as if they were seeing phantom shapes, like the Kanizsa triangle, where Pac-Man cutouts trick you into seeing a triangle that isn’t actually present. The team baptized these cells “IC-encoder neurons,” because a spark from them can ripple outward, recruiting tens of thousands of other neurons to finish the picture.
Shin says she hadn’t expected this “filling-in” to happen so early, right in the brain’s first visual processing area.
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