"The induced trauma to the fly is minimized, and the fly can remain alive longer," Sinha told LiveScience. "Learning and memory experiments in which the brain is imaged before and after training is possible."
Prior research had tried using laser surgery to open holes in animals for intravital microscopy before. Compared to past work that used infrared, visible or larger-wavelength ultraviolet lasers, this new technique can remove tissue more quickly or cause less collateral damage in the brain.
Sinha and his colleagues also successfully tested their technique on anesthetized and immobilized ants, nematode worms and mice. "Our main motivation is to better understand neural circuits, and faster screening and imaging could better help us reverse-engineer these circuits," Sinha said.
From one to 100
The scientists are also developing a way to automatically capture, mount and align the insects for laser surgery. Their short-term goal is to build a system that can hold a dozen flies.
"We are trying to streamline the procedure such that the experimentalist only has to press one button to have the system pick and mount and align 12 flies; a second button that would surgically remove the cuticle and apply saline to the 12 flies; and a third button to start imaging the 12 flies under predetermined stimulation," Sinha said.
Ultimately the researchers would like to simultaneously image the brains of about 100 awake fruit flies with a push of a few buttons, Sinha added.
"Our goal is to have this arrayed imaging technology adopted by a few other labs in the world," Sinha said. "These imaging centers could be used by fly biologists all over the world to conduct new classes of experiments that would not be possible or would be too impractical using traditional techniques."
The scientists detailed their findings online Oct. 28 in the journal Proceedings of the National Academy of Sciences.
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