New Israeli-German study sheds light on how the brain 'sees'

Israeli researchers from Hebrew University and their German colleagues in Munich have conducted a study revealing how the human brain “sees” by transforming visual signals into perception. The study examines how the brain uses information from the eyes to construct meaning and spatial awareness of the external world.

The findings suggest that vision begins long before a complete image is formed in the brain. Initially, the input consists of raw visual data, which is then processed and organized into a coherent and meaningful structure. The process starts in the retina of the eye, which detects light and converts it into electrical signals that are transmitted to the brain for further analysis.

The researchers believe the new study, published in the journal Science, could shape future neuroscience research. It reportedly provides the first evidence supporting the 1962 “feedforward model” proposed by Nobel Prize winners David Hubel and Torsten Wiesel.

Scientific efforts to understand how the brain processes visual information date back more than a century. In 1905, Japanese physician Tatsuji Inouye discovered that damage to the back of the brain resulted in vision loss, ultimately identifying the critical role of the visual cortex. It was not until the 1950s, however, that scientists established that the brain consists of neurons communicating through chemical and electrical signals.

Hubel and Wiesel’s “feedforward model,” introduced in the early 1960s, marked a major breakthrough. It showed that neurons in the retina and thalamus respond to small points of light, while neurons in the visual cortex respond to lines rather than points. For decades, however, technical limitations made it impossible to fully prove their theory.

The new German-Israeli study reportedly provides the first concrete evidence supporting the “feedforward model.” It used advanced two-photon microscopy, enabling imaging at the level of individual synapses—tiny connections between neurons.

The researchers also employed genetically engineered proteins that emit light when they bind to the neurotransmitter glutamate. This combined approach allowed them to observe, in real time, how neurons communicate.

They ultimately succeeded in mapping the input connections to a single neuron, identifying nearly 90 percent of its active excitatory inputs. In addition, they were able to determine which of these inputs originated from the thalamus.

The new study revealed that neurons in the visual cortex are sensitive to orientation and receive input from the thalamic neurons. While providing evidence for the feedforward model, the German and Israeli researchers noted that the model does not address all the aspects of the complex visual processing in the human brain.

Looking ahead, the researchers believe the new study could be the starting point for further exploration of brain function. 

Israel has some of the world’s most advanced hospitals and medical research. In February, researchers at Rambam Health Care Campus in northern Israel presented a promising study that deep-brain stimulation could address schizophrenia.