Scientists Activate Brain Cells to Recreate Illusory Images,raising Questions About Perception
BOSTON,MA - May 2025 – Researchers have successfully activated specific neurons in mice to mimic the brain activity associated with perceiving illusory contours - the phenomenon where we “see” edges that aren’t physically present. The groundbreaking study, published in Nature Neuroscience, offers new insight into how the brain constructs visual reality and opens the door to testing weather artificially induced neural patterns can influence behavior.
The research, led by Shin and colleagues, confirms that neurons responsible for processing illusory contours aren’t isolated anomalies, but a functionally important population within the primary visual cortex.These neurons, dubbed “IC-encoders,” are “causally involved in this pattern completion process that we speculate is highly likely involved in the perceptual process of illusory contours,” according to Adesnik, a researcher involved in the study.
Currently,the work focuses on the neural depiction of these illusions. Researchers used optogenetics to artificially stimulate IC-encoders, successfully recreating the brain activity patterns observed when mice view illusory contours.Though, the team has not yet steadfast if this activation translates to actual perception.
“We didn’t actually measure behavior in this study,” Adesnik explained.”it was about the neural representation.” Shin added, “It’s possible that the mice weren’t seeing them, because the technique has involved a relatively small number of neurons, for technical limitations.”
The current limitations stem from the difficulty of activating a large number of these relatively rare and scattered neurons. “For now, we have only stimulated a small number of these detectors…IC-encoders are a rare population, probably distributed through the layers [of the visual system],” Shin stated.
The team plans to address this by scaling up the experiment. “We could imagine an experiment where we recruit three,four,five,maybe even 10 times as many neurons,” Shin saeid. “In this case, I think we might be able to start getting behavioral responses. We’d definitely very much like to do this test.”
The next step, Adesnik outlined, is to ”photo-stimulate these neurons and see if we can generate an animal’s behavioral response even without any stimulus on the screen.” this research could ultimately shed light on the essential mechanisms of perception and how the brain creates a coherent visual world from incomplete information.
Nature neuroscience, 2025. DOI: 10.1038/s41593-025-02055-5
Federica Sgorbissa is a science journalist; she writes about neuroscience and cognitive science for Italian and international outlets.
