The periaqueductal gray (PAG) is an area of gray matter found in the midbrain, which is associated with the generation of defensive behaviors. 

Low-intensity focused ultrasound stimulation (LIFUS) is gaining traction as a non-surgical experimental approach of modulating brain activity.  

A team of researchers from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences demonstrated that the LIFUS of the PAG induced defensive behaviors in mice brain, the study has been published on IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control. 

The team fabricated a 3.8 MHz head-mounted ultrasound transducer with a small focus size (0.5 mm ×0.5 mm).   

Twelve mice were divided into two groups, the sham group and the ultrasound stimulation group equally, through the real-time place preference test, open field test and rat exposure test, the multiple behavioral processes were orchestrated to observe the complex behavioral patterns.  

The results showed that the LIFUS of the PAG induced multiple defensive behaviors, including location-specific passive avoidance behavior, flight, and freezing and did not cause injury to the brain tissue.  

This study demonstrated that LIFUS of the PAG can induce a series of defensive responses in mice. “We expect that the LIFUS may be used as a novel neuromodulatory tool for the treatment of psychological diseases associated with defensive behaviors in the near future.” Said Dr. NIU Lili. 

Illustration of ultrasound stimulation system. (Image by Dr.NIU Lili)

Media Contact: 
ZHANG Xiaomin 
Email: xm.zhang@siat.ac.cn