For the first time ever, scientists have used a wireless brain implant to make mice socialise with each other, according to a paper published in Nature Neuroscience.
Developed by a team from Northwestern University, US, led by Yevgenia Kozorovitskiy and John A. Rogers, the implant uses the sci-fi-esque technique called optogenetics – using light to stimulate genetically targeted neurons – where the mice had modified neurons with a gene from light-sensitive algae.
Each device was fitted between the skull and skin of the mice and connected to a minuscule, flexible filament-like probe with an LED on it, which bed through the skull into the brain.
When light from the wirelessly controlled LED was delivered to the special neurons, they were stimulated, without affecting other neurons and behaviour.
Using the tiny, battery-free brain implant device, the team were able to program and deprogram mice to socially interact with each other in real-time. When two or more mice had their devices switched on, they interacted much more than usual, and when the device was switched off, the opposite effect was nearly immediate.
The lights stimulated multiple neurons in a network simultaniously, a phenomenon called neural synchrony.
“We didn’t actually think this would work,” says Kozorovitskiy. “To our knowledge, this is the first direct evaluation of a major long-standing hypothesis about neural synchrony in social behaviour.”
“It sounds like sci-fi, but it’s an incredibly useful technique. Optogenetics could someday soon be used to fix blindness or reverse paralysis.”
The researchers hope to learn more about the complex neurology of socialisation.
“This paper represents the first time we’ve been able to achieve wireless, battery-free implants for optogenetics with full, independent digital control over multiple devices simultaneously in a given environment,” says Rogers.
“Brain activity in an isolated animal is interesting but going beyond research on individuals to studies of complex, socially interacting groups is one of the most important and exciting frontiers in neuroscience.”
“We now have the technology to investigate how bonds form and break between individuals in these groups and to examine how social hierarchies arise from these interactions.”
Previously, stimulating neurons relied on fixed fibres that limited the movement. With the wireless device, they were able to observe behaviour uninhibited, they claim.
“With previous technologies, we were unable to observe multiple animals socially interacting in complex environments because they were tethered,” says Kozorovitskiy.
“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.”
Dr Deborah Devis is a science journalist at The Royal Institution of Australia.
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