Scientists at Germany’s TUM have settled a 60-year debate on how mammals see. A team led by Prof. Arthur Konnerth observed the flow of visual information from neuron to neuron. Their work confirms the 1981 Nobel Prize-winning model by Hubel and Wiesel, which some experts had questioned.
The researchers developed a high-resolution imaging method to track synaptic activity in living brains. They published their findings in the journal Science.
The study was led by Prof. Arthur Konnerth, Dr. Yang Chen, and PhD student Marinus Kloos at TUM’s Institute of Neuroscience. The team is also part of the Munich Cluster for Systems Neurology (SyNergy).
For decades, neuroscientists disagreed on one key question: Does the brain’s ability to detect edges and orientations begin in the thalamus or only in the visual cortex? Hubel and Wiesel’s model said the cortex builds this information step by step. But direct proof was missing until now.
The team used two-photon microscopy to see individual synapses in mice. They added fluorescent proteins that glow when synapses fire. Then they showed the mice simple patterns, such as horizontal and vertical stripes, to map which synapses responded.
Using optogenetics, the researchers temporarily muted parts of the cortex with light. This lets them separate signals from the thalamus from those generated in the cortex. The results showed that orientation selectivity — such as distinguishing horizontal from vertical lines — emerges only within cortical circuits.
This technique helps researchers understand how healthy brains process vision. It could also identify faulty circuits in diseases like Alzheimer’s. The method works for many neuron types, making it widely useful, according to TUM.
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The study was done in mice, not humans. And the technique requires specialized equipment, such as two-photon microscopes. More research is needed to apply these findings to human vision disorders.
Confirming this foundational theory strengthens both neuroscience and artificial intelligence. Many AI vision systems are inspired by Hubel and Wiesel’s principles. The study also revealed that not all synapses can learn and adapt, challenging old assumptions about brain plasticity, says Prof. Konnerth.
