Neuroscientists have successfully controlled a fly’s behaviour with thermogenetics – a new technique that uses lasers to remotely activate brain neurons.
Using the whimsically named Fly Mind-Altering Device (also known as FlyMAD), researchers were able to trigger complex courtship behaviour in a target fly, essentially causing the insect to ‘fall in love’ with a ball of wax.
The research, led by Barry Dickson of the Howard Hughes Medical Institute in Ashburn, Virginia, is similar to optogenetics; a method that activates neurons using light and that has previously been used to control behaviour in mice.
However, while optogenetics require fibre-optic cables to be embedded into mice skulls to activate the genetically-altered neurons, thermogenetics achieves the same effect by using infrared lasers to deliver the ‘instructions’ directly to the fly’s brain.
Scientists have previously influenced fly behaviour by adding a heat-activated protein called TRPA1 to neurons associated with certain actions. When flies modified in this way are placed in a hot box the targeted neurons activate and trigger certain behaviours.
FlyMAD, however, uses a video camera to track the fly as it moves around a box before directing an infrared laser at the insect and activating the parts of its neural circuit that control courtship.
In a video from Nature, the subject fly can be seen attempting to mate with a ball of wax, circling and ‘singing’ to it by vibrating its wings. This courtship behaviour continued for 15 minutes after the laser had been shut off “suggesting that the heat had triggered a lasting, complex behavioural state”.
Another test conducted by the neuroscientists was able to instantly make flies walk backwards by activating TRPA1 that had been added to neurons associated with muscular coordination.
The paper written by Dickson and his team is currently awaiting peer review, although some neuroscientists have already welcomed thermogenetics as easier to use than current optogenetic techniques.
Speaking to Nature, Dickson said that he would like to combine the TRPA1 control method with an alternative technique that uses a different light-activated protein known as channelrhodopsin. Scientists say they could then activate different neural circuits at the same time in order to “see which one wins”.