The Brain Sees What the Eyes Cannot, New Study Suggests

Amy Taylor November 05, 2012

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When it comes to processing images, vision is less important. This is the finding of an animal study conducted by a group of researchers from the University of Virginia.

Nick Macedonia, Elizabeth Daubert, and Catherine Hamilton – graduate students of the university, looked at how the fruit fly larvae inputs images into the brain from their limited visual abilities after having noticed a very interesting behaviour of the animal. While conducting a different study on nervous system, the researchers observed that when a larva was tethered to the bottom of the petri dish, others appeared to be attracted to it and travelled toward it.

Poor vision, larger brain

For the current study, the team presented a video of a writhing larva to the fruit fly larvae to test whether they will respond to it or not, considering that there was no vibration, sound or smell. They noticed that the larvae watched the action by wagging their heads side to side, rather than hearing, feeling the vibration or smelling the trapped larva. When the video played in slow motion or at a very fast rate, the larvae were less attracted. They were also not attracted to a dead larva, a tethered larva of another species, or to a larva in near darkness. The researchers were surprised with their findings because fruit flies have very limited vision as they only have 24 total photoreceptors, whereas humans have more than 125 million.

Turns out, the eyes of these animals provide just enough light or visual input to their relatively large brain to convert that input into images. The study shows that visual input may not be as important to the sight as the brain working behind it, said Barry Condron, a neurobiologist in U.Va.’s College of Arts & Sciences who supervised the study.

This special ability of the fruit fly larvae does not lie on their eyes but rather in their brain. Condron explains that the larvae were able to process recognisable images out of a couple dozen points of light captured by their eyes, just like when an astronomer is able to use techniques to refine a limited image of a star using his telescope.

The brain sees what the eyes cannot

According to the researchers, fruit fly larvae tend to recognise their own species because they are visually sensitive to detail and the rate of motion. Their findings are helpful in understanding the role of the brain in helping organisms, including humans in processing images, such as recognising faces; Condron pointed out. The head scanning of these animals also helped them collect information from their limited visual input and put them together to create complex images. Even visually impaired people also scan their heads to accumulate enough light necessary to form mental images.

Fruit flies have been a subject of neurological research by many scientists because they only have around 20,000 neurons, making scientific experiments easier to manage. Cordon said that scientists are currently mapping the entire nervous system of these animals, which will give way to a broader understanding of how neurons work in a range of organisms, including humans. Their findings were published in the journal Nature Communications.

 

Source of this article:

The simple fly larval visual system can process complex images