Leuven researchers discover new connectivity rules in the brain’s visual network

Leuven, Belgium, 17 December 2024 – Researchers at Neuro-Electronics Research Flanders (NERF), led by Prof. Vincent Bonin, have published two new studies uncovering how visual information is processed and distributed in the brain. The studies reveal the complexity and flexibility of visual information processing in the brain.

The visual cortex, a key region for interpreting and processing visual input, plays a crucial role in shaping what we see. Vincent Bonin, a professor at KU Leuven and group leader at NERF, studies the neural circuits that process sensory information. "We often think of visual processing in the cortex as a simple, linear process," explains Prof. Bonin, “but our research shows the cortex operates as a complex network with finely tuned connections between regions, supporting specialized visual functions across distinct brain areas.”

Targeting vs broadcasting

In a first study published in Current Biology, postdoctoral researcher Xu Han revealed how visual information is transmitted across different interconnected regions in the brain. Using advanced imaging and circuit-tracing techniques in mice, Han and Bonin identified pathways that either selectively channel visual signals to targeted areas or broadcast information broadly across multiple regions.  

“For instance, neurons in the pulvinar and certain layers of the cortex are finely tuned to their targets, suggesting a role in constructing detailed visual representations,” explains Han. “In contrast, deeper neurons seem to ignore target specificity, broadcasting similar visual information across areas—possibly for coordinating broader brain activity.”  These findings challenge the long-held belief that visual information flows in a simple, step-by-step manner, instead revealing a highly dynamic and adaptable network.

Quiet vs aroused

In the second study, published in Cell Reports, Bonin and Dr. Karolina Socha (now at the University of California in LA) explored how the brain’s thalamus—a key relay station for visual signals—adjusts information processing depending on behavioral states. The researchers found that during quiet wakefulness, neurons in the thalamus amplify signals for back-to-front motion, a transformation absent under anesthesia or heightened arousal. By imaging the activity of neurons in awake mice, they discovered that this modulation is linked to changes in pupil size, a marker of arousal. 

“Larger pupils coincided with stronger responses to back-to-front motion, suggesting that the thalamus integrates sensory inputs with behavioral context to prioritize certain visual stimuli,” explains Bonin. “These findings demonstrate how the thalamus integrates behavioral context to dynamically shape visual representations, altering how motion is processed and prioritized.” 

Predict and manipulate perception

Together, both studies represent a major step toward creating a detailed “functional-anatomical map” of the brain’s visual system. “Understanding these pathways and mechanisms allows us to predict and manipulate how perception works,” says Bonin. These findings advance neuroscience research and hold promise for developing targeted interventions to modulate brain function.

Publications

Higher-order cortical and thalamic pathways shape visual processing streams in the mouse cortex. Han X, Bonin V. Curr Biol, 2024. DOI: 10.1016/j.cub.2024.10.048.

Behavioral modulations can alter the visual tuning of neurons in the mouse thalamocortical pathway. Socha KZ, Couto J, Whiteway MR, Hosseinjany S, Butts DA, Bonin V. Cell Rep, 2024. DOI: 10.1016/j.celrep.2024.114947.

Funding

The research (team) was supported by VIB, KU Leuven, imec, the Research Foundation Flanders (FWO), and KU Leuven Research Council.