January 7, 2016

What the mouse eye tells the mouse brain

The retina sends information to the brain via some 40 different channels.
Image: CIN/ Tübingen University

(January 7, 2016)  Tübingen researchers have shown that image processing in the eye is more extensive than previously thought. They investigated the channels that transmit information from the eye to the brain. In the course of this investigation, they not only identified numerous new cell types: they also found that the retina seems to possess some 40 different channels into the brain, twice as many as previously assumed. The results of their study are published in the latest edition of Nature. DOI: 10.1038/nature16468

“What the frog’s eye tells the frog’s brain” was the title that cognition scientist Jerome Lettvin gave to a seminal paper published in 1959. He assumed that the eye not only sees, but also processes images – even before they are transmitted to the brain for further processing. Lettvin was able to show that the eye neither simply takes pictures like a camera, nor does it send them to the brain without filtering. Instead, the eye itself extracts valuable information from what it sees. In the case of the frog, for example, it might ‘tell’ the brain: “There is something small and dark there, possibly a fly.” For his revolutionary hypotheses, Lettvin was at first laughed off stage at conferences. In the meantime, though, his oft-quoted paper is considered a milestone. The questions raised in Lettvin’s time are still pursued by scientists today.

A Tübingen-based team of researchers has now tackled these questions anew, led by Prof. Thomas Euler and Prof. Matthias Bethge (Werner Reichardt Centre for Integrative Neuroscience, Bernstein Center for Computational Neuroscience, and Institute for Ophthalmic Research). The neuroscientists wanted to find out which kinds of information about the world the retina transmits to the brain. To this end, they undertook a study on an unheard-of scale, investigating more than 11,000 individual retinal cells in mice - far bigger than the largest similar study to date, which had been content with investigating approx. 450 individual cells.

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