Summary: Researchers have uncovered how visual information is processed across the brain’s complex and flexible networks.
One study showed visual signals are selectively targeted or broadly broadcast, challenging the idea of a simple, linear flow of visual input. A second study revealed that the thalamus adapts visual processing based on behavioral states, prioritizing back-to-front motion during arousal.
Together, these findings reveal dynamic mechanisms that shape perception and offer pathways to manipulate brain function for future interventions.
Key Facts:
- Targeted vs Broadcast Signals: Visual pathways either channel specific signals or broadcast broadly to coordinate brain activity.
- Thalamus Modulation: Visual processing in the thalamus changes with arousal, prioritizing certain motion during heightened states.
- Dynamic Visual Network: The brain adapts visual processing based on behavioral context, not through a fixed, step-by-step process.
Source: VIB
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.
Funding
The research (team) was supported by VIB, KU Leuven, imec, the Research Foundation Flanders (FWO), and KU Leuven Research Council.
About this visual neuroscience research news
Author: India Jane Wise
Source: VIB
Contact: India Jane Wise – VIB
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Higher-order cortical and thalamic pathways shape visual processing streams in the mouse cortex” by Vincent Bonin et al. Current Biology
Open access.
“Behavioral modulations can alter the visual tuning of neurons in the mouse thalamocortical pathway” by Vincent Bonin et al. Cell Reports
Abstract
Higher-order cortical and thalamic pathways shape visual processing streams in the mouse cortex
Mammalian visual functions rely on distributed processing across interconnected cortical and subcortical regions.
In higher-order visual areas (HVAs), visual features are processed in specialized streams that integrate feedforward and higher-order inputs from intracortical and thalamocortical pathways.
However, the precise circuit organization responsible for HVA specialization remains unclear.
We investigated the cellular architecture of primary visual cortex (V1) and higher-order visual pathways in the mouse, focusing on their roles in shaping visual representations.
Using in vivo functional imaging and neural circuit tracing, we found that HVAs preferentially receive inputs from both V1 and higher-order pathways tuned to similar spatiotemporal properties, with the strongest selectivity seen in layer 2/3 neurons.
These neurons exhibit target-specific tuning and sublaminar specificity in their projections, reflecting cell-type-specific visual information flow.
In contrast, HVA layer 5 pathways nonspecifically broadcast visual signals across cortical areas, suggesting a role in distributing HVA outputs.
Additionally, thalamocortical pathways from the lateral posterior thalamic nucleus (LP) provide highly specific, nearly non-overlapping visual inputs to HVAs, complementing intracortical inputs and contributing to input functional diversity.
Our findings suggest that the convergence of laminar and cell-type-specific pathways V1 and higher-order intracortical and thalamocortical pathways plays a key role in shaping the functional specialization and diversity of HVAs.
Abstract
Behavioral modulations can alter the visual tuning of neurons in the mouse thalamocortical pathway
Behavioral influences shape processing in the retina and the dorsal lateral geniculate nucleus (dLGN), although their precise effects on visual tuning remain debated.
Using 2-photon functional Ca2+ imaging, we characterize the dynamics of dLGN axon activity in the primary visual cortex of awake behaving mice, examining the effects of visual stimulation, pupil size, stillness, locomotion, and anesthesia.
In awake recordings, nasal visual motion triggers pupil dilation and, occasionally, locomotion, increasing responsiveness and leading to an overrepresentation of boutons tuned to nasal motion.
These effects are pronounced during quiet wakefulness, weaker during locomotion, and absent under anesthesia.
Accounting for dynamic changes in responsiveness reduces tuning biases, revealing an overall preservation of retinal representations of visual motion in the visual thalamocortical pathway.
Thus, stimulus-driven behavioral modulations can alter tuning and bias classification of early visual neurons, underscoring the importance of considering such influences in sensory processing experiments.
