The clawed frog Xenopus is a predator catching prey at
night by detecting water movements. We present a general
method, a "minimal model" based on a minimum-variance estimator,
to explain prey detection through the frog's lateral-line
organs. Waveform reconstruction allows Xenopus to
determine both direction and character of the prey and even to
distinguish two simultaneous wave sources.
We have produced a video showing how the water surface is
reconstructed by the clawed frog
There are wave sources on the upper left corner of the displayed
water surface and on the upper right corner, with frequencies of
20 Hz (left) and 10 Hz (right). The video plays in slow motion
with a speed of 1/10. The clawed frog assumes the wave sources
in the directions where the reconstructed oscillation of the
water surface has the largest amplitude (displayed in red). The
clawed frog can determine the directions of the wave sources
(left and right ahead) as well as their frequencies (the source
with the higher frequency is on the left).
According to another neuronal model (Franosch 2005), the clawed
frog can even learn to interpret the information it
gets from its lateral-line system. The frog's eyes allow it to
see the water surface. Neurons are excited by the image of the
moving prey as well as by the moving water at Xenopus'
skin. The neurons adapt its connective strengths to the velocity
receptors such that after some time the water wave alone is
sufficient to excite the neurons. The visual image is no more
needed. After the learning process, the neuron that is
responsible for one direction is only activated iff the water
wave originates from the proper direction. So the activity of
the neurons reports the direction where the prey is.
Franosch JMP, Sobotka MC, Elepfandt A and van Hemmen JL.
Minimal Model of Prey Localization through the Lateral-Line System.
Phys Rev Lett 91:1581011-1581014 (2003)
Franosch JMP, Elepfandt A and van Hemmen JL.
Minimal Model of Prey Localization through the Lateral-Line System
, Poster presentation at the Göttinger Neurobiologentagung
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number 653, September 12, 2003.
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geschieht wo auf der Wasseroberfläche?, Short News 2003-11-03,
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Beutefang durch Wellenformanalyse, Physik
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Franosch JMP, Lingenheil M and van Hemmen JL.
How a Frog Can Learn What is Where in the Dark.
Phys Rev Lett 95:078106 (2005)
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Virtual Journal of Biological Physics Research
Volume 10, Issue 4, August 15, 2005.
Leo van Hemmen, Wie funktioniert unser Gehirn?, Mitteilungen
der Technischen Universität München, 3(2005),
last modified 2007-11-05