Advancements in Understanding Visual Processing in the Brain

Recent scientific research has made significant progress in understanding how the brain processes visual information. Researchers have discovered that the ancient visual system, common to all vertebrates, has the ability to independently produce center-surround interactions, which aids in distinguishing edges, contrast, and environmental details that capture attention.

An Ancient Brain System Facing Modern Challenges

For decades, it was believed that these computational processes were exclusive to the visual cortex of the brain. However, new research has shown that the superior colliculus, an evolutionarily ancient brain structure, can also perform these processes independently. Andreas Kardamakis explains that the ability to analyze what we see and determine what deserves our attention is not a modern invention of the human brain but a mechanism that emerged over half a billion years ago.

The superior colliculus functions like an integrated radar, receiving signals directly from the retina before they reach the cortex. It helps identify the most important parts of the visual scene. When something moves, glimmers, or appears suddenly, this structure reacts first, directing the eyes toward the new stimulus.

Advanced Tools in Studying Visual Processes

To study how these processes occur, the team used advanced tools such as optogenetics, electrophysiology, and computational modeling. By using light to activate specific retinal pathways and recording responses in mouse brain slices, they discovered that the superior colliculus can suppress a central visual signal when the surrounding area becomes active—a hallmark of center-surround processing.

This effect was supported by cell-type-specific mapping and large-scale computational simulations. Kuei Song, the co-first author of the research paper, explains that the superior colliculus not only transmits visual information but actively processes and filters it, reducing the response to uniform stimuli and enhancing contrast.

Evolutionary Roots and Cognitive Significance

These discoveries challenge the traditional belief that complex visual processing occurs only in the cortex. Instead, they support a hierarchical model where ancient brain structures handle essential computational processes crucial for survival, such as threat detection, motion tracking, or obstacle avoidance.

Understanding how these ancestral structures contribute to visual attention also helps in understanding what happens when these mechanisms fail. Disorders such as attention deficit disorder, increased sensory sensitivity, or certain forms of traumatic brain injuries may partly arise from disrupted communication between the cortex and these fundamental circuits.

Conclusion

This research represents a broad international collaboration between the Karolinska Institute, the Royal Institute of Technology in Sweden, and the Massachusetts Institute of Technology in the United States. These discoveries have contributed to a deeper understanding of how nervous systems evolved and how structures like the superior colliculus found in fish, amphibians, reptiles, birds, and mammals share a common goal: integrating sensory and motor information to guide gaze and attention.

This work was supported by the Spanish Government Research Agency, the Severo Ochoa Program for Excellence, the Regional Government of Valencia, the Swedish Research Council, the Swedish Brain Foundation, and the Olle Engkvist Foundation.