Scientists have genetically modified fruitflies to let them smell blue light - it smells of bananas to them, apparently.
The Ruhr University researchers did it by activating a single receptor neuron out of 28 olfactory neurons in the Drosophila larvae.
The olfactory neurons of the larvae - just one millimeter long - are all capable of producing the protein that is activated by light.
The researchers were able to activate either cells which normally register repulsive odors, or those that sense attractive odors such as banana, marzipan or glue.
The activated neurons send an electrical signal if they are stimulated with blue light at a wavelength of 480nm. The larva thus has the impression that it perceives odors.
Moreover, the researchers found they could measure the effect electrophysiologically, using thin electrodes to detect the signal of the light-activated neurons. They were able to follow the transmission of the nerve signal all the way into the brain, enabling non-invasive observation of neural networks.
The researchers now plan to use the same principle with adult Drosophila, equipping them with photo-activated proteins to cause targeted isolated cerebral neurons to react. They also hope to repeat the trick with mice.
The fidings appear inFrontiers in Behavioral Neuroscience.