Sometimes what we see does not immediately make sense. A shadow can briefly resemble a face, or one object can momentarily be mistaken for another. New research suggests that the brain may resolve these visual conflicts by allowing different regions to compare their interpretations until a more consistent picture emerges.
In a study published in Nature Neuroscience, Cold Spring Harbor Laboratory Cynthia R. Stebbins Fellow Mitra Javadzadeh and collaborators at the University of Cambridge and University College London examined how two neighboring regions of the visual cortex interact. They found that when activity in the two regions matched, the shared pattern persisted. When the regions produced conflicting patterns, however, the disagreement faded within a fraction of a second.
The findings offer a possible explanation for how the brain combines information from specialized regions into a single, coherent perception.
How Specialized Brain Regions Work Together
Different parts of the brain are responsible for processing different streams of sensory information, yet our experience of the world usually feels unified rather than fragmented. Understanding how those specialized systems coordinate with one another is a major challenge in neuroscience.
"We are trying to understand how you can have such a high level of specialization between these different blocks, yet always have a consistent holistic outcome," Javadzadeh says.
The researchers focused on two well known visual processing regions in the brain's neocortex: the primary visual cortex (V1) and the lateromedial visual area (LM). Visual processing does not simply move in one direction from one region to the next. Instead, these areas continually exchange information with each other.
Testing What Happens When Visual Areas Disagree
To explore that communication, Javadzadeh and her colleagues trained mice to tell the difference between two visual patterns tilted in opposite directions. The animals received a reward for recognizing only one of the orientations.
During the task, the researchers temporarily silenced either V1 or LM and watched how the remaining region behaved without its usual partner. The team then used those observations to create an artificial neural network model of the V1-LM circuit. With that model, they could test how the system might respond when particular neurons were altered.
The results revealed a striking pattern. Activity that conflicted between the two brain regions quickly disappeared, while activity shared by both areas lasted longer.
"We find that over time, these types of connections between areas implement a mechanism we call consensus building," Javadzadeh explains.
A Possible Brainwide Consensus Mechanism
The study examined only two regions involved in vision, but the researchers are now investigating whether the same process may operate more broadly across the neocortex.
"For example, when what you see contradicts with what you hear, do you still use the same kind of mechanisms to reconcile these two?" she wonders.
If dynamic consensus building turns out to be widespread, it could help scientists better understand how the brain combines competing signals into a stable interpretation of the world. It could also shed light on what happens when different brain regions fail to arrive at the same conclusion.
The idea may even have implications beyond neuroscience. Similar principles could help researchers think about how artificial intelligence systems might handle conflicting streams of information and decide which signals to trust.
"While we understand individual building blocks of the brain, what is the glue that puts them together?" Javadzadeh asks. "Knowing that can finally help us understand how the brain works as a whole."
