Scientists are using light to switch nerve cells on and off in the brains of mice wearing headsets and backpacks to study the animals’ social behaviour, a new study shows. These remote control experiments are elucidating new information about the neural circuitry underlying social interactions. Previous corroborating research suggests that minds in sync are more cooperative. Professor Yevgenia Kozorovitskiy, a neurobiologist at Northwestern University and colleagues, reported on May 10 in the journal Nature Neuroscience.
The new devices are based on optogenetics, a technique in which researchers use bursts of light to activate or suppress brain nerve cells, or neurons, frequently by genetically engineering cells to respond to illumination. Optogenetics has been used to probe neural circuits in mice and other laboratory animals to gain insight into how they might function in humans.
Although optogenetic devices frequently deliver light to neurons via fibre-optic cables, these tethers can impair natural behaviours and social interactions. While scientists have developed implantable wireless optogenetic devices in recent years, these devices rely on relatively simple remote controls or a small set of preprogrammed instructions.
These newly developed fully implantable optogenetic arrays for mice and rats may enable more advanced research. Precisely, the researchers can adjust the programming of each device during experiments, “allowing for a much more complex targeting of what an animal does,” says Yevgenia Kozorovitskiy, a neurobiologist at Northwestern University.
These battery-free, head- and back-mounted devices are powered wirelessly by the same high-frequency radio waves used to control the intensity, duration, and timing of the light pulses remotely. Additionally, the prototypes enable scientists to manage four distinct neural circuits in an animal simultaneously, thanks to LEDs that emit four different colours — blue, green, yellow, and red — rather than just one.
Kozorovitskiy and colleagues used the devices to target the prefrontal cortex, a region of the brain associated with decision-making and other complex behaviours, in mice experiments. When the researchers applied similar patterns of neural stimulation to pairs or trios of mice, they observed that the rodents groomed and sniffed their companions more frequently than those with whom their neurons were out of sync. The findings corroborate previous research suggesting that this type of mental synchrony can enhance social behaviour, “particularly cooperative interactions,” according to Kozorovitskiy.
The widely available wireless technology used in this work, which is also used in contactless credit card payments, may enable widespread adoption across the neuroscience community “without requiring extensive specialized hardware,” according to neurotechnologies Philipp Gutruf of the University of Arizona at Tucson, who was not involved in the research. This “means that in the near future, we may see these devices in a large number of laboratories, enabling discoveries.” The insights gained from such research into the nervous system, he says, may help “inform better diagnostics and therapeutics in humans.”
Yang, Y., Wu, M., Vázquez-Guardado, A. et al. Wireless multilateral devices for optogenetic studies of individual and social behaviors. Nat Neurosci (2021). https://doi.org/10.1038/s41593-021-00849-x
Main Image Credit: Rama, CC BY-SA 2.0 FR, via Wikimedia Commons
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