Brain cells for 3D vision discovered

Summary: Researchers have identified neurons in the brains of praying mantises that are able to compute 3D direction and distance. The findings may help to develop better technology for machine and robotic vision.

Source: Newcastle University

Scientists at Newcastle University have discovered neurons in insect brains that compute 3D distance and direction. Understanding these could help vision in robots.

In stunning images captured under the microscope for the first time, the neurons were found in praying mantises. The work is published in Nature Communications today.

In a specially-designed insect cinema, the mantises were fitted with 3D glasses and shown 3D movies of simulated bugs while their brain activity was monitored. When the image of the bug came into striking range for a predatory attack, scientist Dr Ronny Rosner was able to record the activity of individual neurons.

This shows the neurons
3D neuron captured by microscope. The image is credited to the researchers.

Dr Rosner, Research Associate in the Institute of Neuroscience at Newcastle University, is lead author of the paper. He said: “This helps us answer how insects achieve surprisingly complex behaviour with such tiny brains and understanding this can help us develop simpler algorithms to develop better robot and machine vision.”

The “3D neurons”

Praying mantises use 3D perception, scientifically known as stereopsis, for hunting. By using the disparity between the two retinas they are able to compute distances and trigger a strike of their forelegs when prey is within reach.

The neurons recorded were stained, revealing their shape which allowed the team to identify four classes of neuron likely to be involved in mantis stereopsis.

The images captured using a powerful microscope show the dendritic tree of a nerve cell – where the nerve cell receives inputs from the rest of the brain – believed to enable this behaviour.

This shows the optic nerve
Neuron connecting optic nerves. Credit: The researchers.

Dr Rosner explains: “Despite their tiny size, mantis brains contain a surprising number of neurons which seem specialised for 3D vision. This suggests that mantis depth perception is more complex than we thought. And while these neurons compute distance, we still don’t know how exactly.

“Even so, as theirs are so much smaller than our own brains, we hope mantises can help us develop simpler algorithms for machine vision.”

The wider research programme which is funded by the Leverhulme Trust, is led by Professor Jenny Read, professor of Vision Science at Newcastle University. She says: “In some ways, the properties in the mantises are similar to what we see in the visual cortex of primates. When we see two very different species have independently evolved similar solutions like this, we know this must be a really good way of solving 3D vision.

This shows a praying mantis wearing the 3D glasses
Praying mantis wearing 3D glasses. Credit: The researchers.

“But we’ve also found some feedback loops within the 3D vision circuit which haven’t previously been reported in vertebrates. Our 3D vision may well include similar feedback loops, but they are much easier to identify in a less complex insect brain and this provides us with new avenues to explore.”

It’s the first time that anyone has identified specific neuron types in the brain of an invertebrate which are tuned to locations in 3D space.

The Newcastle team intend to further develop their research to better understand the computation of the relatively simple brain of the praying mantis with the aim of developing simpler algorithms for machine and robot vision.

About this neuroscience research article

Newcastle University
Media Contacts:
Ronny Rosner – Newcastle University
Image Source:
The image is credited to the researchers.

Original Research: Open access
“A neuronal correlate of insect stereopsis”. Ronny Rosner, Joss von Hadeln, Ghaith Tarawneh & Jenny C. A. Read.
Nature Communications. doi:10.1038/s41467-019-10721-z


A neuronal correlate of insect stereopsis

A puzzle for neuroscience—and robotics—is how insects achieve surprisingly complex behaviours with such tiny brains. One example is depth perception via binocular stereopsis in the praying mantis, a predatory insect. Praying mantids use stereopsis, the computation of distances from disparities between the two retinal images, to trigger a raptorial strike of their forelegs when prey is within reach. The neuronal basis of this ability is entirely unknown. Here we show the first evidence that individual neurons in the praying mantis brain are tuned to specific disparities and eccentricities, and thus locations in 3D-space. Like disparity-tuned cortical cells in vertebrates, the responses of these mantis neurons are consistent with linear summation of binocular inputs followed by an output nonlinearity. Our study not only proves the existence of disparity sensitive neurons in an insect brain, it also reveals feedback connections hitherto undiscovered in any animal species.

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