Brain cartography: the fly mating dance neurons mapped

Wien (OTS) - How the bundles of neurons in the brain control
behaviour remains an ongoing mystery. Researchers from the Institute
of Molecular Pathology (IMP), in Vienna, Austria, and the Laboratory
of Molecular Biology (LMB/MRC), Cambridge, United Kingdom, have
mapped neurons of the fruit fly, Drosophila, that control sexual
behavior. "We literally untangled the mess of wires in the fly brain
and laid the ground plans for investigating a complex behavior in a
simple organism," says Jai Yu, whose doctoral work will be published
in Current Biology.

Not only do animals come in different shapes and sizes, variety is
certainly not lacking when it comes to behavior. Each species is born
with its own unique set of behaviours but how this is controlled by
the brain is not well understood. This is where the fruit fly,
Drosophila, can help. Sex is a behaviour the fruit fly does well.
Their amazing reproductive prowess has ensured their successful
spread throughout the world. Unlike their human counterparts, the
male fruit fly is born knowing very well how to impress the female.
Its brain is fully equipped with the right neurons that allow it to
perform an intricate mating dance to woo the female for copulation.

For his PhD work in Barry Dickson's laboratory at the Institute of
Molecular Pathology (IMP), in Vienna, Jai Yu used clever genetic
tricks to see individual types of neurons in the tiny brain of the
fruit fly that are known to be important in controlling its mating
dance, or courtship dance. These neurons are called fruitless neurons
because they express a critical gene, fruitless, that is needed for
fruitful reproduction. "At the beginning, we knew there's about 2% of
the fly brain, which is around 1500 individual neurons, that are
important for courtship, but we didn't know how many types or groups
of neurons they belong to. We now know there are at least 100
different types based on where they connect to," says Jai Yu, "We
think each type of neuron is important in some way and together all
the components work hand in hand to generate the courtship dance."

This work was possible by looking at the miniscule brains, at less
than a millimeter across, of thousands of different genetic strains
of Drosophila, each one having a different group of neurons made
visible with a fluorescent protein. "It was like a giant jigsaw
puzzle, where each fly strain provided a piece and we had to put
together the complete picture one strain at a time," explains Jai Yu.
After meticulously analysing a large collection of images of fruit
fly brains using a combination of microscopy and advanced digital
imaging software, Jai Yu could connect the pieces and reveal a map of
mating dance neurons, "What we did was similar to making an
electronic circuit diagram, looking at how the parts are connected."
The finding opens up many avenues of research, particularly it offers
a chance to really know how these 100 different types of neurons in
the fly nervous system orchestrate the mating dance. "What excites me
now is instead of looking at these neurons we have a way to go back
to our selection of fly strain that we have used and try to shut the
neurons down, something like pulling out the wires, one by one, to
see what happens to the mating dance of the fly," Jai Yu says, "then,
we can find which ones do what by looking at the defects during the
mating dance."

The implications from this research are wide reaching. Although
the fly brain is small and relatively simple, it offers a chance to
understand how collections of neurons allow an animal to perceive the
environment and interact with it. "I look forward to a time in the
near future, where we can understand what goes on in the brain of the
little fruit fly, how it has become so efficient at doing things,
eat, sleep and reproduce," says Jai Yu, "I hope through our efforts,
the brain will become less of a mystery and more of a tangible entity
that we can one day understand."

Rückfragehinweis:

Dr Barry Dickson 
   Institute of Molecular Pathology 
   Dr Bohrgasse 7 1030 Vienna 
   mailto:[email protected] 
   
   Dr Jai Yu Institute of Molecular Pathology 
   Dr Bohrgasse 7 1030 Vienna 
   mailto:[email protected]

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