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.