On July 8, 2022, Zhang Zhi's team from the School of Life Sciences and Medicine at the University of Science and Technology of China, in collaboration with Yuanyuan Liu's team from the National Institutes of Health and Wenjuan Tao's team from Anhui Medical University, made progress in the neural circuit mechanism of acoustic analgesia. The work was published in the journal Science under the title "Sound induces analgesia through corticothalamic circuits."

As early as 1960, a paper in Science found that music can regulate mood, and even noise can produce direct analgesic effects. However, for half a century, the key factors and neural mechanisms of acoustic analgesia have not been understood. The researchers first gave the pain mice different intensities of harmonized sounds (as opposed to human music), unharmonized sounds (non-musical structured sounds), and white noise, and found that only low intensities of all three types of sounds were effective in relieving pain in the mice. Since there are studies suggesting that the analgesic effect of sound is closely related to the treatment environment, the researchers found that the sound intensity difference (SNR) of about 5-dB relative to the ambient noise is crucial to the analgesic effect of sound by studying the environment with different background sounds. At this point, the researchers established a mouse model of acoustic analgesia.

So what is the neural mechanism by which sound exerts its analgesic effect? The auditory cortex (ACx) is the most advanced center for sound processing, so the researchers tracked ACx output across the brain through viral tracers. It was found that glutamate neurons (ACxGlu) of ACx mainly project to the somatosensory thalamus, which is closely related to pain processing. Acoustical exposure to 5-dB SNR inhibited ACxGlu thalamic projection through in vivo electrophysiology and in vivo deep calcium imaging. Photogenetic and chemogenetic studies have shown that 5-dB SNR inhibits ACxGlu from projecting into the thalamus to relieve pain in mice (Figure 1). In conclusion, this study reveals that the sound intensity difference from environmental noise is crucial for sound pain relief, and further reveals the fine neural circuit mechanism of sound analgesia.

Figure 1: Low intensity sound-to-noise ratio alleviates pain in mice by inhibiting ACxGlu projection into the thalamus.

Dr. Zhou Wenjie, a special associate researcher at the University of Science and Technology of China, doctoral student Ye Chonghuan, Professor Wang Haitao from Anhui University of Traditional Chinese Medicine, and doctoral student Mao Yu are the first authors of this paper. Zhang Zhi from the Department of Life Sciences and Medicine at the University of Science and Technology of China, Tao Wenjuan from Anhui Medical University, and Liu Yuanyuan from the National Institutes of Health in the United States are the co corresponding authors of this paper. The collaborators of this study include Dr. Zhao Wan from the Otolaryngology Department of the First Affiliated Hospital of the University of Science and Technology of China and Professor Chen Lin from the Department of Life Sciences and Medicine of the University of Science and Technology of China. They have received funding from the National Natural Science Foundation of China, the Science and Technology Innovation 2030 (China Brain Program) of the Ministry of Science and Technology of China, the National Research Center for Microscale Materials Science in Hefei, the Hefei University of Science and Technology Center, the Key Laboratory of Brain Function and Brain Disease of the Chinese Academy of Sciences, and the University of Science and Technology of China.


Article link:https://www.science.org/doi/10.1126/science.abn4663

(Department of Life Sciences and Medicine, Department of Scientific Research)
Source: HKUST News Network