Post date: Nov 08, 2013 2:47:46 PM
Scientists in the US are planning to map the brain activity of the dragonfly as it hunts, using a specially built backpack to transmit electrical signals from the insect's active neurons to a computer. The researchers believe that, if successful, their experiments could shed light on how the human brain functions and how degenerative diseases like Parkinson's and Alzheimer's develop.
ASHBURN, VIRGINIA, UNITED STATES (REUTERS) - At rest, the dragonfly is a picture of energy conservation. It barely moves as it waits for its next meal to fly past, but when it spots an approaching insect, it launches into action, taking flight on four independently moving wings. At the same time, it must make a series of lightning-fast calculations in order to anticipate its prey's position relative to its own, and adjust its flight path accordingly before catching the fly.
It's a process that fascinates neuroscientist Anthony Leonardo and his team at the Janelia Farm campus of the Howard Hughes Medical Institute in Ashburn, Virginia.
"We are interested in how the brain solves problems and one very common problem that dragonflies, and amphibians and people experience all the time is catching a moving object," said Leonardo. "You know, so something's moving through the air and you're in one location and it's in another location and to get it, you have to do two things at once. You have to predict where it's going to be in the future and you have to find a way to navigate your body along that interception course."
In order to find out exactly how the human brain processes information from the point of stimulus to action, Leonardo is using the far simpler and more accessible dragonfly brain as a model. He plans to combine two proven technologies in one larger experiment - to track the insect's neuronal activity as it hunts.
He's already demonstrated that a dragonfly is capable of carrying a backback weighing about 40 milligrams, equal to about ten percent of its own weight, with minimal interference to its movement. In laboratory experiments he's also shown that electrodes inserted into the dragonfly's brain can record the electrical activity of neurons when the animal is stimulated. Now, he and his colleagues have attached to the backback, the electrodes and a tiny chip that amplifies electrical signals, which they plan to use for the dragonfly hunting project.
Leonardo has created a room at Janelia Farm, designed to replicate the natural environment of the dragonfly. Temperature and humidity are controlled by sensors and a spring meadow scene is painted on the walls. Eighteen high speed cameras surround a central platform where fruitflies will be released for the dragonflies to hunt. The cameras will track the movement of tiny metallic balls attached to the dragonflies' wings.
"So we track the location of those little balls while the animal is flapping the wings and moving the head at very high spatial resolution and we can essentially figure out what the animal sees, what neurons are active and how the wings are being steered, and that's sort of the idea in these experiments, we can record almost all the, sort of, variables that the animal is looking at and the things that he's controlling," said Leonardo.
Crucially, the experiments will also record the animal's neuronal activity. The lightweight backback will be attached to the anaesthetised dragonfly and connected to its brain via a thin wire. When the insect wakes up, and begins to hunt, the backback will transmit the electrical signals produced as the neurons fire.
The job of building the backback fell to instrument and systems designer, Jason Osborne. He says that creating the tools to fit a living animal with miniaturised technology was a technical challenge.
"There's a lot of trial and error, there's a lot of fails but, nevertheless, you're trying to do something that noone has done before so the inventing process and the trouble shooting and the R and D is just mind-blowing," he said.
Ulitmately, Leonardo says he hopes the project will lead to a greater understanding of how the human brain works. If neuronal activity can be tracked in a simple animal like the dragonfly, he believes the lessons learned could be applied to humans, particularly for the treatment of mysterious neuronal conditions like Alzheimer's and Parkinson's disease.
"If you really want to help people in terms of malfunctioning brains or disease and other things, I mean one way to do it, the standard way we do it is with molecular tools and therapeutic things but really, if you go to your car mechanic he understands how the parts work, how they fit together and how they interact, and that's what we're trying to do here and build up an understanding of how the parts work," he said.