Brain’s “Internal Construction” of Vision Revealed by New Research
Scientists have identified a key mechanism in the brain responsible for constructing our perception of reality, rather than passively receiving it. Research led by teams at the Allen Institute and Berkeley, and published in Nature Neuroscience, details the role of specialized neurons, termed IC-encoders, in the primary visual cortex. these neurons appear to be crucial in creating visual perceptions even when the actual sensory input is incomplete or absent.
The study demonstrates that higher-level brain areas can “instruct” lower-level visual areas to perceive specific shapes or objects. this process is analogous to a manager assigning a task to an employee – instructions originate from higher cognitive centers and are then executed by neurons in the visual cortex. Researchers illustrated this with the example of perceiving a square formed by four incomplete circles, where the brain actively constructs the complete shape despite the fragmented visual stimulus.
The discovery stemmed from observing electrical brain activity in mice presented with illusory images like the Kanizsa triangle. Researchers utilized two-photon holographic optogenetics to stimulate IC-encoder neurons even without presenting an illusory image. Remarkably, this stimulation triggered the same brain activity patterns observed when the illusion was present, effectively recreating the perception internally.
“The findings shed light on how the visual system and perception work in the brain and have implications for diseases where this system malfunctions,” explains Jerome Lecoq,Ph.D., associate investigator at the Allen Institute. He highlights the relevance to conditions like schizophrenia, where abnormal object representations can emerge spontaneously. “if you don’t understand how those objects are formed and a collective set of cells work together to make those representations emerge, you’re not going to be able to treat it; so understanding which cells and in which layer this activity occurs is helpful.”
The research benefited from the Allen Institute’s OpenScope program, which provides external scientists access to advanced tools and equipment. Specifically, six Neuropixels probes allowed researchers to observe the feedback loops between brain areas with millisecond precision. This confirmed the existence of this “feedback loop” - communication from higher-order brain regions to lower visual areas containing the IC-encoders – in mice.
This study shifts the understanding of vision from a passive intake of data to an active process of interpretation and construction. Rather than functioning like a camera, the brain operates more like a computer monitor, generating a visual experience based on complex calculations and prior experiences. This suggests a greater potential for influencing and manipulating our perception of reality.
Source: Shin, H., et al. (2025). Recurrent pattern completion drives the neocortical portrayal of sensory inference. Nature Neuroscience. doi.org/10.1038/s41593-025-02055-5
