New Wireless Brain Imaging Method Could Advance Social Neuroscience

Osaka, Japan – Electrophysiological and fluorescence-based brain imaging techniques in mice are generally invasive, require head fixation or cables, and are unsuitable for long-term recordings. Although there has been recent advances in imaging methods in animals moving freely, these are important limitations for researchers who are interested in the brain correlates social behaviors.

Researchers at Osaka University have come up with a new method to record brain activity simultaneously in multiple, free-moving mice. The method is based on a bioluminescence-based recent indicator of membrane voltage called "LOTUS-V". The LOTUS-V bioluminescent probe is genetically encoded, which means that it is transmitted to target cells non-invasively via a common gene expression system (the adeno-badociated virus). Its signal is derived from voltage changes in the cell membrane, which reflect brain activity.

"The LOTUS-V method reported brain activity in mice moving freely with good sensitivity and without movement artifacts," says author Takeharu Nagai correspondent. "More importantly, it could measure the dynamic evolution of brain activity in the primary visual cortex during social interactions. "

LOTUS-V has been applied to cells in the primary visual cortex; this area has been targeted as it is known to react to locomotor activity and visual stimulation. LOTUS-V changes reflect the neuronal activity in response to visual stimuli and locomotor activity, as well as during interactions with other mice; Neuronal activity was significantly higher when one mouse approached the others. In addition, the LOTUS-V signal was not affected by signals emitted by other people's leaks, nearby mice, which means that it accurately reflects brain activity in vivo.

"Our method successfully detected activity of the superficial layer of the primary visual cortex – it is about 300 μm deep," says Shigenori Inagaki, the study's first author. "It will be important to test its applicability to recording in deeper brain regions."

If the temporal resolution of the LOTUS-V method was sufficient to study the dynamics of brain activity triggered by specific events, it is not yet superior to that of the fiber-based method.

"These results could be really exciting for social neurobiologists," said Nagai. "It is non-invasive, does not require cables or headband, and is suitable for long-term recordings on animals in free movement, which means that it could also be useful in many other areas of research . "

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The article titled "Local brain activity imaging of multiple free-roaming mice sharing the same environment," was published in Scientific reports at DOI: https: //do I.org /ten.1038 /s41598-019-43897-x

About the University of Osaka

Osaka University was founded in 1931 as one of the seven imperial universities of Japan and is now extended to one of Japan's leading comprehensive universities. The university is today the most innovative in Japan and one of the most innovative institutions in the world according to the Top 100 Innovative Universities of Reuters 2015 and Nature Index Innovation 2017. The capacity of the # 39 university to innovate from the stage of basic research through the creation of useful technologies with an economic impact stems from its broad disciplinary spectrum.

Website: https: //resou.Osaka-u.ac.jp /fr /top