Sound induces analgesia through corticothalamic circuits

Sound induces analgesia through corticothalamic circuits. Wenjie Zhou et al. Science, Jul 7 2022, Vol 377, Issue 6602, pp. 198-204, DOI: 10.1126/science.abn4663

The pain-reducing effects of music: That sound can effectively suppress pain has been known for some time. However, it is still unclear what drives the analgetic effect induced by music or noise. Zhou et al. used a range of methods to demonstrate in mice that the auditory cortex is functionally connected to regions involved in nociception (see the Perspective by Kuner and Kuner). The neuronal circuits depend on the physical location of the pain. Whereas the analgetic effect of a 5-decibel signal-to-noise ratio white noise on the hindpaws involved projections from the auditory cortex to the posterior thalamic nuclei, on the forepaws, it involved projections from the auditory cortex to the ventral posterior nuclei. Distinct thalamic nuclei are thus involved in the processing of nociceptive information perceived at distinct physical locations. —PRS

Abstract: Sound—including music and noise—can relieve pain in humans, but the underlying neural mechanisms remain unknown. We discovered that analgesic effects of sound depended on a low (5-decibel) signal-to-noise ratio (SNR) relative to ambient noise in mice. Viral tracing, microendoscopic calcium imaging, and multitetrode recordings in freely moving mice showed that low-SNR sounds inhibited glutamatergic inputs from the auditory cortex (ACxGlu) to the thalamic posterior (PO) and ventral posterior (VP) nuclei. Optogenetic or chemogenetic inhibition of the ACxGlu→PO and ACxGlu→VP circuits mimicked the low-SNR sound–induced analgesia in inflamed hindpaws and forepaws, respectively. Artificial activation of these two circuits abolished the sound-induced analgesia. Our study reveals the corticothalamic circuits underlying sound-promoted analgesia by deciphering the role of the auditory system in pain processing.

Popular version: Soft sounds numb pain. Researchers may now know why. Experiments in mice show how sound tamps down on pain processing in the brain. Tess Joosse. Science News, Jul 7 2022. https://www.science.org/content/article/soft-sounds-numb-pain-researchers-may-now-know-why