Imagine a world where our brains can perceive what isn't physically present. Scientists have long speculated about specific neurons responsible for such phenomena, and a recent study led by researcher Shin and his team has dramatically shifted our understanding. They have discovered that these neurons are not mere anomalies; rather, they constitute a vital and well-defined group that plays a significant role in visual processing. As Shin states, "What we didn’t know is that these neurons facilitate local pattern completion within the primary visual cortex." His colleague Adesnik expands on this by mentioning, "We have demonstrated that these neurons are causally connected to the pattern completion process, which we believe plays a critical role in the perception of illusory contours."
But here’s where it gets intriguing—the mere activation of these neurons in mice did not ensure that they actually perceived the illusory contours. "We didn’t focus on behavioral measurements in this research," Adesnik clarifies. "Our main objective was to understand the neural representation itself." Presently, all we can definitively conclude is that these IC-encoders can trigger neural activity patterns similar to those observed during the usual perception of illusory contours.
Acknowledging the limits of their study, Shin concedes, "There’s a chance that the mice did not really see these contours, as our technique involved stimulating a fairly small number of neurons due to technical constraints. However, we can envision broadening the neuron count and incorporating behavioral assessments in future investigations."
This brings us to the exciting next steps in their research, as Adesnik explains: "Our goal is to utilize photo-stimulation on these neurons to observe if we can elicit a behavioral reaction from animals, even without any visual stimulus displayed on the screen." Currently, optogenetics—an advanced method that uses light to control neurons—can only engage a limited number of neurons, and the IC-encoders are infrequently located and dispersed.
"For the time being, we have only targeted a handful of these detectors, primarily due to technical restrictions. IC-encoders are a rare group, possibly spread throughout the layers of the visual system. However, we can envision a future experiment where we might recruit three, four, five, or even ten times as many of these neurons," he notes. "In that scenario, we could potentially start observing actual behavioral responses, and we profoundly wish to conduct such tests."
This groundbreaking research, published in Nature Neuroscience in 2025, raises intriguing questions about how we perceive reality and the neural mechanisms behind it. Do you think the brain's ability to fill in gaps in our visual field is more than just a neat trick? Are we truly aware of everything we see, or do we construct our reality from pieces of information? Share your thoughts and let’s spark a lively discussion!
