Researchers provide standardized nomenclature for the architecture of insect brains

When you’re talking about something as complex as the brain, the task isn’t any easier if the vocabulary being used is just as complex. An international collaboration of neuroscientists has not only tripled the number of identified brain structures, but created a simple lexicon to talk about them, which will be enormously helpful for future research on brain function and disease.

Nick Strausfeld and Linda Restifo, both professors in the Department of Neuroscience at the University of Arizona, worked with colleagues in Japan who led the project, and colleagues in Germany and in the UK to produce a comprehensive atlas of neuroanatomical centers and computational centers of the insect brain. In the process, the team identified many previously unknown structures. By providing the research community with a unified system of terminology, they set the stage for a systematic effort to elucidate brain structures and functions that carry over to functions of the human brain.

An article about the work appears in the scientific journal Neuron, regarded by many as one of the flagship publications of neuroscience; the online version includes an 80-page data supplement. The data will be publicly available within 6 months and include hundreds of images and 3-D video animations – amounting to an invaluable resource that will enable neuroscientists to work more efficiently, compare their results and obtain more meaningful interpretations.

"This effort provides a three-dimensional road map for describing structures for all insect brains, and enables comparisons with other arthropods," said Strausfeld, director of the UA Center for Insect Science. "It has huge value in describing network relationships between computational centers in the brain."

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Learned helplessness in flies and the roots of depression

When faced with impossible circumstances beyond their control, animals, including humans, often hunker down as they develop sleep or eating disorders, ulcers, and other physical manifestations of depression. Now, researchers reporting in the Cell Press journal Current Biology on April 18 show that the same kind of thing happens to flies.

The study is a step toward understanding the biological basis for depression and presents a new way for testing antidepressant drugs, the researchers say. The discovery of such symptoms in an insect shows that the roots of depression are very deep indeed.

"Depressions are so devastating because they go back to such a basic property of behavior," says Martin Heisenberg of the Rudolf Virchow Center in Würzburg, Germany.

Heisenberg says that the idea for the study came out of a lengthy discussion with a colleague about how to ask whether flies can feel fear. Franco Bertolucci, a coauthor on the study, had found that flies can rapidly learn to suppress innate behaviors, a phenomenon that is part of learned helplessness.

The researchers now show that flies experiencing uncomfortable levels of heat will walk to escape it. But if the flies realize that the heat is beyond their control and can’t be avoided, they will stop responding, walking more slowly and taking longer and more frequent rests, as if they were “depressed.”

Intriguingly, female flies slow down more under those stressful circumstances than males do. It’s not clear exactly what that means, but Heisenberg explains, “if we realize that the fly trapped in a strange, dark box, unable to get rid of the dangerous heat pulses, has to find a compromise between saving energy and not missing any chance of escape, we can understand that such a compromise may come out differently for males and females, as their resources and goals in life are different.”

Heisenberg’s team now intends to explore other questions, such as: How long does the flies’ depression-like state last? How does it affect other behaviors, like courtship and aggression? What is happening in their brain? And more.

Heisenberg says that the findings are a reminder of a lesson that children’s books are often best at showing: “Animals have lots in common with us humans. They breathe the same air, share many of the same resources, actively explore space, and have distinct social roles. Their brains serve the same purpose, too: they help them to do the right thing.”

Researchers identify brain pathway triggering impulsive eating

New research from the University of Georgia has identified the neural pathways in an insect brain tied to eating for pleasure, a discovery that sheds light on mirror impulsive eating pathways in the human brain.

"We know when insects are hungry, they eat more, become aggressive and are willing to do more work to get the food," said Ping Shen, a UGA associate professor of cellular biology in the Franklin College of Arts and Sciences. "Little is known about the other half-the reward-driven feeding behavior-when the animal is not so hungry but they still get excited about food when they smell something great.

The fact that a relatively lower animal, a fly larva, actually does this impulsive feeding based on a rewarding cue was a surprise.”

The research team led by Shen, who also is a member of the Biomedical and Health Sciences Institute, found that presenting fed fruit fly larvae with appetizing odors caused impulsive feeding of sugar-rich foods. The findings, published Feb. 28 in Cell Press, suggest eating for pleasure is an ancient behavior and that fly larvae can be used in studying neurobiology and the evolution of olfactory reward-driven impulses.

To test reward-driven behaviors in flies, Shen introduced appetizing odors to groups of well-fed larvae. In every case, the fed larvae consumed about 30 percent more food when surrounded by the attractive odors.

But when the insects were offered a substandard meal, they refused to eat it.

"They have expectations," he said. "If we reduce the concentration of sugar below a threshold, they do not respond anymore. Similar to what you see in humans, if you approach a beautiful piece of cake and you taste it and determine it is old and horrible, you are no longer interested."

Shen’s team also tried to further define this phenomenon-the connection between excitement and expectation. He found when the larvae were presented with a brief odor, the amount of time they were willing to act on the impulse was about 15 minutes.

"After 15 minutes, they revert back to normal. You get excited, but you can’t stay excited forever, so there is a mechanism to shut it down," he said.

His work also suggests the neuropeptides, or brain chemicals acting as signaling molecules triggering impulsive eating, are consistent between flies and humans. Neurons receive and convert stimuli into thoughts that are then relayed to the downstream mechanism telling the animals to act. These signaling molecules are required for this impulse, suggesting the molecular details of these functions are evolutionarily tied between flies and humans.

"There are hyper-rewarding cues that humans and flies have evolved to perceive, and they connect this perception with behavior performance," Shen said. "As long as this is activated, the animal will eat food. In this way, the brain is stupid: It does not know how it gets activated. In this case, the fly says ‘I smell something, I want to do this.’ This kind of connection has been established very early on, probably before the divergence of fly and human. That is why we both have it."

Impulsive and reward-driven behaviors are largely misunderstood, partially due to the complex systems at work in human brains. Fly larvae nervous systems, in terms of scheme and organization, are very similar to adult flies and to mammals, but with fewer neurons and less complex wirings.

"A particular function in the brain of mammals may require a large cluster of neurons," he said. "In flies, it may be only one or four. They are simpler in number but not principle."

In the fly model, four neurons are responsible for relaying signals from the olfactory center to the brain to stimulate action. Each odor and receptor translates the response slightly differently. Human triggers are obviously more diverse, but Shen thinks the mechanism to appreciate the combination is likely the same. He is now working with Tianming Liu, assistant professor of computer science at UGA and member of the Bioimaging Research Center and Institute of Bioinformatics, on a computer model to determine how these odors are interpreted as stimuli.

"Dieting is difficult, especially in the environment of these beautiful foods," Shen said. "It is very hard to control this impulsive urge. So, if we understand how this compulsive eating behavior comes about, we maybe can devise a way, at least for the behavioral aspect, to prevent it. We can modulate our behaviors better or use chemical interventions to calm down these cues."

Electronic brain hacks are turning insects into robotic helpers

We’re a long way from directly controlling human minds remotely, but recent years have seen a string of breakthroughs in hacking the minds of insects. Insect brains are probably the simplest interesting brains, as insects can perform a range of tasks (flying, smelling, carrying, etc.) with brains that have numbers of neurons orders of magnitude less than those in complex vertebrates. A fruit fly has around 100,00 neurons, compared to 85 billion in humans.

So at the conjunction of neuroscience and robotics lie insects — their tiny brains still too complex to model completely, but offering an easy way into modelling certain parts of the brain. It’s how engineers from Sheffield and Sussex universities can claim they’re preparing to upload the smell and sight parts of a bee’s brain into a bee-like flying robot, enmeshed with human-created software to create a completely new “brain”.

The hope is that the bee-bot could fly in areas that other robots can’t fit, like a collapsed building. And it makes sense to use nature’s own smell modules instead of developing new ones — their combination of efficiency in size and operation is so far unmatched by anything synthetic. A bee-bot could smell out explosives in a warzone, or drugs in shipping containers, or any of many other myriad uses, and actually go investigate. They can even be used as little spies. Who would notice a fly sitting on the wall of a meeting room?

A lot of research in the area of bug brains is being funded by the US Defense Advanced Research Projects Agency (Darpa), the Pentagon agency which seeks out new technologies for military use. It’s not hard to imagine a future where drones are grown on farms, with extra controls implanted at the larval stage — a process developed by bionic researchers at North Carolina State University.

Insects change the way they communicate when drowned out by man-made noises

Birds and frogs do it, even whales have been known to do it. Now scientists have for the first time shown that insects also change the way they sing to one another when drowned out by man-made noises.

Click HERE to listen to a grasshopper battling traffic noise

Grasshoppers living next to a main road respond to the increased background volume of passing traffic by adjusting their summer courtship songs, scientists have discovered.

In order to make themselves heard above the low-rumble noise pollution of moving vehicles, male bow-winged grasshoppers of central Europe alter the pitch of their songs’ lower notes so that they rise to a mini-crescendo, the scientists found.

“Bow-winged grasshoppers produce songs that include low and high frequency components,” said Ulrike Lampe of the University of Bielefeld in Germany, who led the study published in the journal Functional Ecology.

“We found that grasshoppers from noisy habitats boost the volume of the lower-frequency part of their song, which makes sense since road noise can mask signals in this part of the frequency spectrum,” Dr Lampe said.