Most people would have to agree, trying to hit and kill a fly can be a challenging business. Michael Dickinson, a professor who researches the biomechanics of insect flight at the California Institute of Technology, has recently discovered why flies are so hard to swat. Dickinson used high-resolution, high-speed digital imaging to record the flies reaction to being swatted at by a 14-centimeter-diameter black disk. What he and his graduate student, Gwyneth Card, found was that in about 100 milliseconds time the fly is able to not only calculate the direction and angle that the threat is coming from, but also to orient its body in the optimal direction for takeoff before it flies off unscathed. "This illustrates how rapidly the fly's brain can process sensory information into an appropriate motor response," Dickinson says. The fly was also found to be able to make “planning movements prior to take-off” and adjust It's movements according to the position it was in. Once again, in only 100 milliseconds,
“The fly must integrate visual information from its eyes, which tell it where the threat is approaching from, with mechanosensory information from its legs, which tells it how to move to reach the proper preflight pose. This means that the fly must integrate visual information from its eyes, which tell it where the threat is approaching from, with mechanosensory information from its legs, which tells it how to move to reach the proper preflight pose."
It is suggested in the article that there could be “some sort of map in which the position of the looming threat is transformed into an appropriate pattern of leg and body motion prior to take off”. These findings remind me of the owl and its kidney shaped optic tectum. It seems to me that because the fly is able to accurately adjust to the angle and location it is being swatted from, that there could be some part of it's brain where neurons are laid out as some sort of spatial map that will rapidly fire neurons connecting the visual input from the flies many eyes to its legs and body. Also, the fly is able to respond so quickly, and in the appropriate direction that it seems strikingly similar to the crayfish's ability to move it's tail in response to an attack. This makes me wonder if the neurons involved are large in size to allow for such a fast reaction time. Dickinson said, "This is a rather sophisticated sensory-to-motor transformation, and the search is on to find the place in the brain where this happens."
This press release was found on the Caltech Media Relations website. Dickinson's paper, “Visually Mediated Motor Planning in the Escape Response of Drosophila," will be published August 28 in the journal of Current Biology.
Posted by: Rachel Carboni (1)
posted by PWH @ 11:10 PM
9 comments
9 Comments:
I think the fly has this reaction advantage not only because of the "wiring" difference in our brains but also because of the size difference. Flies don't really possess a brain as much as they have a group of tightly nit ganglion in their head.The fact that these ganglion are so close together and small allows information to travel exponentially faster than our hands can clap together. On a less serious note I have a sure fire way to not miss those flies. If you clap your hands laterally about 1 inch above the fly its survival rate becomes very low.
Patrick Salome
How did the 14 centimeter black disk move? I was wondering if it was automated by controls or by other means. The mechanosensory information from the fly's legs tells it how to move to reach the proper preflight pose. What is the proper preflight pose? How does being in the proper preflight pose help the fly to escape?
The fly must integrate visual information from its eyes with mechanosensory information from its legs. I wasnt sure if this is supposed to happen together to get a response from the fly. What would happen if the fly did not get any information from its eyes or legs?
SUSAN DUONG
This makes sense because a fly has a short life, and so it needs to be able to do what it needs to do in less time than other animals.
-Sasha Rogers
Interesting article, i knew flies were quick but 100 milliseconds is very fast. I wonder what a flies reaction time is in relation to an average humans reaction time?
Alex Pavidapha
I am also curious to know how the black disc moved in the experiment. You mention that the visual input from the fly's many eyes to its legs and body is the sensory connection for a "fly away". I am curious to know if perhaps the fly senses air pressure or vibrations, through the hairs on their body, and interprets them also as a threat for survival. Perhaps they have a similar sensory road-map for a vibration or air pressure stimulus?
Maura Mulvey
I am also curious to know how the black disc moved in the experiment. You mention that the visual input from the fly's many eyes to its legs and body is the sensory connection for a "fly away". I am curious to know if perhaps the fly senses air pressure or vibrations, through the hairs on their body, and interprets them also as a threat for survival. Perhaps they have a similar sensory road-map for a vibration or air pressure stimulus?
Maura Mulvey
I wonder how scientists calculated the response time. They said these flies have 100 milliseconds response time. They are such small in size. As a result, it will be hard to wire equipments to the fly, and calculate neurons firing.
Also, if they had technology to determine the response time, how did they determine when flies responded to the threat? We cannot control how flies move, so it is very hard to determine whether the flies ran away from the black disk, or just random movements.
Yi, Jeongsang.
wow 100 milliseconds i takes humans .1 seconds to blink. it pays to have a simple brain. this article was very interesting. no wonder it is soo hard to kill them.
Matthew Sousa
The article doesn't specify how the black disc moves. At one point it mentions that it moves toward the fly at a 50 degree angle so I would think it could be set up to some sort of automated control so this could be measured and accurately adjusted. As for the "proper preflight pose", I think that all this means is that the fly positions its legs in the correct way in response to the threat so that when it flaps its wings and takes off, it is angled in the opposite direction. If it is approached from the side it will lean it's body to the other side and then fly off.
If the fly didn't get any information from its eyes or legs then I would guess that it wouldn't live very long. At the same time, someone mentioned that it could sense vibrations in the air, which seems logical because it does have tiny hairs on it's legs. If you blew on a fly I think it could either respond and fly away or it would just stay put because it can't fly away every time the wind blows. I'm sure it uses other stimuli other then sight, but when it comes time to make a quick decision it has the means to respond in time by using visual cues.
In order for the scientists to determine the response time they must have spent a lot of time reviewing the video of the fly frame by frame. I bet they had to decide ahead of time what would be considered a "preflight" pose and set some sort of a standard. No matter how they did this, I imagine it was very tedious work and someone had to spend a lot of time watching for slight movements in the legs.
Rachel Carboni
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