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It's hard to imagine an experiment more suited to stoking conspiracy theorists' fears: researchers have increased social bonding among mice using light-producing brain implants. Human brains are certainly more complex and harder to control than those of rodents, but the work raises the possibility of using technology to enhance social mingling – potentially whether the subjects like it or not. Suddenly, compulsory ice-breaker games don't seem so bad.
Optogenetics is a rapidly growing field in which light is used to turn gene activity on and off. In some cases, it has been used to activate specific neurons, a process that started with invertebrates such as snails or dragonflies, but which has now moved on to our fellow mammals. Neurons are modified to express a gene from light-sensitive algae. When exposed to light of a particular wavelength, the neuron is stimulated, creating ripple effects that can alter behavior.
Advances in optogenetics have been hampered, however, by the need to deliver the light through fibreoptic wires which prevented the free movement of the subjects – a limited problem for snails perhaps, but an obstacle with fast-moving mice. A team at Northwestern University has overcome this, and Dr Yevgenia Kozorovitskiy used the development to control animal interactions.
"With previous technologies, we were unable to observe multiple animals socially interacting in complex environments because they were tethered," Kozorovitskiy said in a statement. "The fibers would break or the animals would become entangled. In order to ask more complex questions about animal behavior in realistic environments, we needed this innovative wireless technology. It's tremendous to get away from the tethers."
Kozorovitskiy and colleagues achieve this by implanting wireless devices that fit between the skull and skin of the mouse. A filament extends into the brain with an LED on the end positioned next to the target neuron.
In Nature Neuroscience, the authors describe using this control as a sort of photonic soma, integrating the mice into the collective before reversing the process. Instead of triggering neurons associated with particular movements or senses, as in the past, researchers activated neurons in the parts of the brain associated with socialization. In one experiment, unfamiliar mice were paired up and their brains stimulated simultaneously. Almost half the pairs of mice engaged in social behavior such as grooming and sniffing with the strangers.
When the mice were given unsynchronized signals, only a quarter of the mouse pairs interacted, and for a shorter period.
A second experiment placed mice together in threes, with the neurons of two of the mice triggered simultaneously. The third mouse also had its neurons activated, but using a different frequency from the other two. The two who were literally operating on the same frequency interacted with each other more than with the third mouse.
"It sounds like sci-fi, but it's an incredibly useful technique," Kozorovitskiy said. "Optogenetics could someday soon be used to fix blindness or reverse paralysis." Likely benefits could extend to treating mental illness.
However, it's easy to imagine the resistance efforts to apply optogenetics to humans will face. After all, if people can oppose vaccines on the entirely false grounds that they could contain microchips to control our behavior – something that is far beyond our technological capacity even if anyone wished it – imagine the response when someone actually tries to conduct experiments with mind control that could actually work, making individuals behave in ways deemed more socially desirable.
