Sound may hold key to healing, accordign to the findings of a recent study by researchers at the NIH/National Institute of Dental and Craniofacial Research; the University of Science and Technology of China, Hefei; and Anhui Medical University, Hefei, China. The team has pinned down neural mechanisms which can reduce the intensity of pain through sounds.
The findings of the study has been published in the journal Science, and they confirm that there could be safe, non-invasive methods to treat pain.
Rena D’Souza, NIDCR Director, said that by uncovering the circuitry that controls pain-killing effects of sound in mice, the study could ultimately help uncover new approaches for pain reduction.
Music and sound therapy
Music has the ability to put us in a good mood. We have long believed that listening to melodious sounds can improve health and harsh, non-rhythemic ones are bad. However, this study uncovered some surprising findings.
In the mid 20th century, research made big strides in the field of pain management through sound and music therapy, which targets both chronic and acute pain stemming from surgery, labour and cancer. However, the exact mechanism is still unclear.
Some parts of the human brain could play a role in music-induced analgesia; but the study on mice has been able to explore the circuitry more efficiently, according to the researchers.
To conduct the experiment, the researchers exposed the mice with inflamed paws to sounds: classical music, a garbled form of the same piece and white noice.
They noticed that all the three types of sound when they were played at a low intensity, helped reduce pain sensitivity in the rodents.
When they dialed up the intensity of the same sounds, it had no effect on the animals’ pain responses.
The surprising find was that the intensity of the sound mattered and not the pleasantness of the sound.
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The researchers used non-infectious viruses with flourescent proteins to map out the connections in the brain areas. With this, they were able to trace a route from the auditory cortex (which helps us process information about sound) to the thalamus (a reception and relay station for pain signals).
In the mice, low-intensity white noise reduced the activity of neurons at the reception end of the thalamas pathway.
When there was no sound, the pathway was suppressed with light and small molecule-based techniques, which mimicked the pain-reducing effects of low-intensity noise.
When the pathway was turned on, the animals’ pain sensitivity was restored.
The researchers said it’s unclear whether these brain processes and perceived mood of the sounds in mice are the same as those in humans for pain relief.
Emotional components of music may have different meanings to humans, said the researchers and it’s not clear whether mice also respond to music in the same way.
However, these findings could make a world of difference to pain research. They could provide safer alternatives to opioids that lead to addiction.
Wenjie Zhou, Chonghuan Ye, Haitao Wang, Yu Mao, Weijia Zhang, An Liu, Chen-Ling Yang, Tianming Li, Lauren Hayashi, Wan Zhao, Lin Chen, Yuanyuan Liu, Wenjuan Tao, Zhi Zhang. Sound induces analgesia through corticothalamic circuits. Science, 2022; 377 (6602): 198