A novel way to control the brain and muscles of tiny organisms, including freely moving worms has been discovered by researchers who are using inexpensive components from ordinary liquid crystal display (LCD) projectors.
Red, green and blue lights from a projector activate light-sensitive microbial proteins that are genetically engineered into the worms, allowing the researchers to switch neurons on and off like light bulbs and turn muscles on and off like engines.
The new study has shed light on how the inexpensive illumination technology allows researchers to stimulate and silence specific neurons and muscles of freely moving worms, while precisely controlling the location, duration, frequency and intensity of the light.
"This illumination instrument significantly enhances our ability to control, alter, observe and investigate how neurons, muscles and circuits ultimately produce behavior in animals," said Hang Lu, of the Georgia Institute of Technology.
"Because the central component of the illumination system is a commercially available projector, the system's cost and complexity are dramatically reduced, which we hope will enable wider adoption of this tool by the research community," explained Lu.
By connecting the illumination system to a microscope and combining it with video tracking, the researchers are able to track and record the behavior of freely moving animals, while maintaining the lighting in the intended anatomical position.
When the animal moves, changes to the light's location, intensity and color can be updated in less than 40 milliseconds.
Once Lu and her team built the prototype system, they used it to explore the 'touch' circuit of the worm Caenorhabditis elegans by exciting and inhibiting its mechano-sensory and locomotion neurons.
The findings were reported in the advance online edition of the journal Nature Methods.