Surprising similarity in fly and mouse motion vision

[Jim__]

From MedicalXpress:

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At first glance, the eyes of mammals and those of insects do not seem to have much in common. However, a comparison of the neural circuits for detecting motion shows surprising parallels between flies and mice. Scientists have learned a lot about the visual perception of both animals in recent years. Alexander Borst at the Max Planck Institute of Neurobiology in Martinsried and Moritz Helmstaedter at the Max Planck Institute for Brain Research, both of whom have made a significant contribution to the current level of knowledge in the case of flies and mice, have now demonstrated the similarities.

A fly's eye consists of more than a thousand individual facets and can cover most of the head's surface. This provides flies with a panoramic view, as it were. Human eyes, in comparison, are small but mobile. Both can see colour, but the colour spectra are different. The fly brain can also detect more than 80 images per second separately from one another, while our limit is 24 images per second. Insects therefore see rapid movements much better and more precisely than we humans.

Despite all these differences, "seeing" is an essential sense for flies and humans – and their eyes face a similar problem: individual photoreceptors only "see" individual pixels in an overall image. The brain therefore needs to compute shapes, distances or movements from these individual items of information. But how? In their comparison of the visual systems of flies and mice, Alexander Borst and Moritz Helmstaedter have now been able to demonstrate that a few very efficient basic rules apparently determine these computations. "Insects and mammals are separated by about 550 million years of development and yet there are surprising parallels in how their brains process visual motion information," explains Alexander Borst, who, together with his department at the Max Planck Institute of Neurobiology, analysed the neural circuits underlying motion vision in the fly brain. "It looks as if we have a very robust solution for computing the direction of motion with neurons," adds his colleague Moritz Helmstaedter, who studies the wiring diagram of the mouse brain at the Max Planck Institute for Brain Research. In their article in the journal Nature Neuroscience, the two researchers have now elaborated the system parallels.

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Photoreceptors respond to changes in contrasts – they increase or reduce their activity depending on whether a previously bright point darkens or a dark point brightens. A number of years ago, Alexander Borst and his team demonstrated that photoreceptors in the fly eye pass their information onto two groups of cells: one responds only to a dark-light change ("light on&quot , the other group recognizes only light-dark changes ("light off&quot . Scientists have known about a similar separation of contrast changes in the form of ON and OFF bipolar cells in the mammalian retina for more than 40 years. This parallel, however, is just the first of several similarities.

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[Jack-o-Lantern]

1. Interesting.