Wintery Knight

…integrating Christian faith and knowledge in the public square

Target acquisition and interception in dragonflies

Here is a fascinating post about some of the capabilities of dragonflies from Evolution News.

Selective attention

First, dragonflies have “selective attention” – the ability to focus on a single prey and ignore other distractions:

Dragonflies are among the best flyers in the insect world. Their twin pairs of paper-thin wings allow them to hover and move in all directions, even in mating. When the time comes to dart after prey at high speed, they rarely miss.

What’s their secret? One is “selective attention” — a trait previously known only in primates, according to new research from the University of Adelaide, Australia. Selective attention is the ability to focus on one object and exclude others. Just as a tennis player must focus on the ball and ignore the cheers of the crowd, a dragonfly must pick out one target from a swarm of insects and avoid being distracted by all the others.

Here’s a snip from the research paper:

Our data make a compelling case that CSTMD1 reflects competitive selection of one target. We emphasize “competitive,” because the attended target is not always the same between trials or even within a trial, as seen in strikingly perfect switches from one to the other…. Competition is further suggested by rare examples where the activity observed under Pair stimulation initially lags both T1and T2 responses… suggesting initial conflict in the underlying neural network before resolution of competition by a “winning” target.

We previously showed that CSTMD1 still responds robustly to a target even when it is embedded within a high-contrast natural scene containing numerous potential distracters. Taken together with recent evidence that the behavioral state of insects strongly modulates responses of neurons involved in visuomotor control, our new data thus suggest a hitherto unexpected sophistication in higher-order control of insect visual processing, akin to selective attention in primates.Perhaps the most remarkable feature of our data is that once the response “locks” onto a target (or following a switch), the second target exerts no influence on the neuron’s response: the distracter is ignored completely.

In order to succeed at the task of catching its prey, the dragonfly has to tune out all other distractions.

Target selection

In addition, dragonflies have the ability to intercept a target in mid-air – similar missile defense systems on AEGIS cruisers and destroyers.

The Evolution News article explains:

Another paper on dragonflies shows that these marvels of the insect world are equipped with navigational equipment that can do vector calculus. In the Proceedings of the National Academy of Sciences, Gonzalez-Bellido and a team at the Howard Hughes Medical Institute discerned “Eight pairs of descending visual neurons in the dragonfly [that] give wing motor centers accurate population vector of prey direction.

Intercepting a moving object requires prediction of its future location. This complex task has been solved by dragonflies, who intercept their prey in midair with a 95% success rate. In this study, we show that a group of 16 neurons, called target-selective descending neurons (TSDNs), code a population vector that reflects the direction of the target with high accuracy and reliability across 360°. The TSDN spatial (receptive field) and temporal (latency) properties matched the area of the retina where the prey is focused and the reaction time, respectively, during predatory flights. The directional tuning curves and morphological traits (3D tracings) for each TSDN type were consistent among animals, but spike rates were not. Our results emphasize that a successful neural circuit for target tracking and interception can be achieved with few neurons and that in dragonflies this information is relayed from the brain to the wing motor centers in population vector form.

What did I make of this? Well, evidence like this always causes me to think aboutthe reality of God, and the disturbing thought that we do not live in an accidental universe where I can do whatever I want and be accountable to no one. It’s easier to believe that – it requires less work and it frees us to be our own boss and make our happiness the first priority. As individuals, it’s very tempting for us to think that we are number one, and to resent our obligations to anyone else. The problem is that the scientific data doesn’t support that worldview. The facts are what they are and it is up to us, now, to try to find out who the designer is and what he wants from us.

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