Thalamus Transmits Broadly Tuned Signals to the Visual Cortex: TUM Study in Science Supports Hubel and Wiesel Model

There are moments in science when the past and present converge in a point of quiet recognition. An idea once conceived almost by intuition returns decades later as clear knowledge, finally given form and substance.

This is precisely what occurred in a study published in the journal Science on March 26, 2026. Researchers from the Technical University of Munich have reached one of the most subtle levels of visual perception—the point where light is just becoming a signal, and the signal is preparing to become meaning.

They traced the path of visual information through the thalamus, an ancient structure that funnels sensory impulses to the cortex. And they observed a simple and precise pattern: the thalamus transmits raw material. Pure, stable, and reliable. Not yet organized into an image.

The signals reaching the cortex retain this primary form. They do not yet distinguish between vertical and horizontal, nor has their structure been revealed. Only within cortical networks does orientation selectivity emerge—the moment a line gains direction and the visual field begins to form a world.

This gradually confirms the central idea of David Hubel and Torsten Wiesel's model: perception is built in stages, moving from the simple to the complex. What sounded like a bold hypothesis in the 20th century is now unfolding at the level of individual synapses, with a degree of precision that was once only a dream.

To reach this level of detail, researchers utilized tools that until recently seemed beyond the realm of possibility. Two-photon microscopy allowed for the observation of individual synaptic activity in the living brain. Fluorescent proteins made signal transmission visible. Optogenetics enabled the researchers to temporarily alter cortical circuit activity, thereby isolating the thalamic contribution from the processes occurring within the cortex itself.

This comparison proved to be the key. Thalamocortical inputs demonstrated strength and stability while maintaining minimal orientation tuning. In contrast, intracortical connections showed flexibility and plasticity; it was here that calcium signals associated with learning and reorganization occurred. A clear picture emerges: the thalamus provides the raw materials, and the cortex learns to transform them into perception.

A simple yet profound picture takes shape. The thalamus is the flow. The cortex is the transformation. One provides the entry point. The other creates the space where the image arises.

At this juncture, neuroscience begins to speak of more than just the brain. It touches upon the future of technology. Modern artificial intelligence systems follow the same path—moving from raw signals to complex recognition. As the principles of sequential perceptual assembly are uncovered, the architectures of future intelligent systems become clearer. One can already sense the engineering involved—precise, calibrated, and yet remarkably alive.

Light enters us without form.
Only in the depths of living connections does it become a world.