Misophonia — responding to everyday sounds with extreme anger and anxiety — is associated with stronger connections between both the auditory and visual cortex, as well as the area of the brain associated with orofacial movements, according to a recent study to be published in the Journal of Neuroscience.
Sounds that come from facial movements, such as eating, drinking, and chewing, typically trigger anger in people with misophonia.
The researchers analyzed resting state fMRI connectivity in 16 women with misophonia and 17 controls. The researchers captured 10 minutes of resting state fMRI data. The researchers also used results from a previous misophonia fMRI study that measured evoked-sound response in 20 women with misophonia and a control group of 22, age- and sex-matched.
The fMRI data analysis showed misophonia is characterized by the following:
- Increased resting-state functional connectivity between the orofacial motor area and both the auditory and visual cortex.
- Increased functional connectivity between the auditory cortex and orofacial motor areas in response to all types of sound.
- Increased activation of the orofacial motor area in response to trigger sounds. Specifically, activation of the orofacial motor area increases in proportion to the misophonic distress. There was no difference from the control group in the activation of auditory cortex to trigger sounds and other sounds.
- Increased resting-state functional connectivity between the vPMC (ventral pre-motor cortex) containing the orofacial motor area and insula in the resting state.
The researchers also found that “spontaneous fluctuations in auditory/visual cortex and the orofacial motor cortex are synchronized to a greater extent in the misophonia group compared to the control group.” This stronger connection means the orofacial motor cortex is “primed to respond” in people with misophonia.
This study had some limitations. The researchers said that fMRI measurements are too “coarse” to reveal the workings of single neurons, which means their evidence is indirect. Also, debate remains over to what extent misophonia can be explained by other disorders.
Misophonia is typically characterized as a “disorder of sound emotion processing.” This research suggests “an alternative but complementary perspective on misophonia that emphasizes the action of the trigger-person rather than the sounds which are a by-product of that action. Sounds, in this new perspective, are only a ‘medium’ via which action of the triggering-person is mirrored onto the listener. This change in perspective has important consequences for devising therapies and treatment methods for misophonia. It suggests that instead of focusing on sounds, which many existing therapies do, effective therapies should target the brain representation of movement.”
Disclosure: One study author declared support from the Misophonia Research Fund and REAM Foundation, USA. Please see the original reference for a full list of authors’ disclosures.
Kumar S, Dheerendra P, Erfanian M, et al. The motor basis for misophonia. J Neurosci. 30 June 2021, 41 (26) 5762-5770. doi:10.1523/JNEUROSCI.0261-21.2021