Optical illusions explained in a fly's eyes

Date:
August 24, 2020
Source:
Yale University
Summary:
Why people perceive motion in some static images has mystified not
only those who view these optical illusions but neuroscientists
who have tried to explain the phenomenon. Now neuroscientists have
found some answers in the eyes of flies.



FULL STORY ========================================================================== [Close-up of a fly's eyes | Credit: (c) tomatito26 / stock.adobe.com]
Close-up of a fly's eyes (stock image).

Credit: (c) tomatito26 / stock.adobe.com [Close-up of a fly's eyes |
Credit: (c) tomatito26 / stock.adobe.com] Close-up of a fly's eyes
(stock image).

Credit: (c) tomatito26 / stock.adobe.com Close Why people perceive
motion in some static images has mystified not only those who view
these optical illusions but neuroscientists who have tried to explain
the phenomenon. Now Yale neuroscientists have found some answers in the
eyes of flies, they report Aug. 24 in the Proceedings of the National
Academy of Sciences.


==========================================================================
It turns out that flies are fooled by optical illusions as easily
as humans.

"It was exciting to find that flies perceive motion in static images the
same way we do," said Damon Clark, associate professor of molecular,
cellular and developmental biology and of physics and of neuroscience
at Yale.

The small brains of flies make it easy to track the activity of neurons
in their visual system. Two members of Clark's lab, Margarida Agrochao
and Ryosuke Tanaka, presented flies with optical illusions [see video
link below]. They then measured the flies' behavior to check whether the insects perceive the motion in this optical illusion the same way humans
do. Flies instinctively turn their bodies toward any perceived motion;
when presented with the optical illusion, the flies turned in the same direction as the motion that humans perceive in the pattern.

At the same time, the researchers examined specific neuron types that
govern motion detection in flies and found a pattern of responses created
by the static pattern. By turning those same neurons on and off, the researchers were able to change flies' perception of illusory motion. By turning off two types of motion-detecting neurons, they eliminated
the illusion entirely. By turning off just one of the two types, they
created flies that perceived illusory motion in the opposite direction
than they did with both neurons active. Based on this data the researchers theorized that the optical illusion results from small imbalances in how
the different types of motion detectors contribute to how flies respond,
or don't respond, to illusions.

Since there are similarities between fly and human visual processing,
the researchers designed experiments to test whether the theory they
developed for flies might also apply in humans. They asked 11 participants
to tell them about the motion they saw in the visual illusion. Those experiments suggested -- not surprisingly -- that human visual systems
are more complicated than flies', but the results suggested a similar
mechanism underlies this illusion of motion in humans.

"The last common ancestor of flies and humans lived a half billion years
ago, but the two species have evolved similar strategies for perceiving motion," Clark said. "Understanding these shared strategies can help us
more fully understand the human visual system."

========================================================================== Story Source: Materials provided by Yale_University. Original written
by Bill Hathaway. Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
* YouTube_video:_Optical_Illusions_Explained_in_a_Fly's_Eyes ========================================================================== Journal Reference:
1. Margarida Agrochao, Ryosuke Tanaka, Emilio Salazar-Gatzimas,
Damon A.

Clark. Mechanism for analogous illusory motion perception in flies
and humans. Proceedings of the National Academy of Sciences, 2020;
DOI: 10.1073/pnas.2002937117 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200824170451.htm

--- up 6 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)