How a fly logically grooms itself can shed light on how its brain--and that of higher creatures--drives sequential behaviors.

A behavioral study by a team from the Janelia Research Campus at the Howard Hughes Medical Institute focused on the search for the neural circuits that control grooming in fruit flies.

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"This kind of logical architecture might underlie lots of sequences," said Julie Simpson who led the research.

Simpson and her team wanted to comprehend how animals are able to carry out a sequence of activities that add up to more complicated behaviors. To attain this aim, the team focused on observing how fruit flies act when dirty.

The act of grooming in an animal or insect is an instinctual motor sequence in the species. Understanding its circuits and logic could provide information on other types of sequences such as individual steps of an intricate courtship dance or a string of words an individual puts together to create a statement.

For such complex behaviors, it's important that each move is accomplished in a particular order. Less precise sequences should be carried out one step at a time.

"You can't do everything at once," Simpson said, "so how do you manage competing demands on your limbs and brain so that you execute things in order of importance?"

Andrew Seeds, a postdoctoral researcher and a colleague of Simpson's, coated flies in dust and observed how they groomed themselves.

He found the insects clean themselves with a predictable pattern of cleaning movements.

"Flies have to decide which body part to groom, and once they've cleaned one body part, there's a new decision of which of the remaining body parts to groom. This series of choices leads to the emergence of a sequence," he said.

The team used fruit flies that were developed with sets of neurons that could be switched on or off by exposing the insects to mild heat.

Seeds was able to make a fruit fly groom itself because of the heat, even if it was clean. A dust-covered fly initiates its normal grooming sequence but never goes further than the area the activated neurons are responsible for.

"This deep understanding of the behavior changes the search image of what neural circuits we are looking for," Simpson said. "I think we are now looking for the right things with a formidable set of tools." 

Tagsneurons, brain, Neural activity, brain function, Fly, Research