Misophonia

Misophonia is a condition where people have extreme distress towards everyday bodily sounds like eating, chewing, breathing etc which are called trigger sounds. I am investigating the neuropathophysiology underlying this condition.

The contents of this page are embargoed until further notice.

Here are a couple of projects that I worked on:

Brain activation to trigger sounds

  • In addition to Left Anterior Insula as reported in Sukhbinder Kumar, et. al., Curr. Biol. (2017), we also find Motor and somatosensory areas show increased activation in Misophonics compared to matched healthy controls in response to any sounds.

  • Further we see a differential brain activation in response to trigger sounds over aversive or neutral sounds more so in Misophonia subjects than matched controls in these sensory-motor brain regions especially the brain area that is involved in representing lip, tongue and jaw movement.

Sound Evoked Response

Motor and somatosensory brain areas show increased activation in Misophonia subjects compared to controls in response to sounds.

Activation to sound types

There is a differential brain activation in response to trigger sounds over aversive / neutral sounds more so in Misophonics than controls in (B) motor and (C) somatosensory regions esp. (D) area representing chewing.

Functional Connectivity during sound perception

  • We found that the functional connectivity of secondary auditory cortex (right Planum Temporale) to motor cortex is higher in Misophonia subjects than matched controls during perception of all kinds of sounds (trigger, aversive, and neutral sounds).

  • We also found that the functional connectivity of brain area representing lip, tongue, jaw movement to secondary auditory cortex (right PT) is higher in Misophonia subjects than matched controls during perception of any kind of sounds.

Sound triggered network

Secondary auditory cortex (right PT) has enhanced functional connectivity to bilateral motor cortex in response to any kind of sound.

Chewing area connections

Brain area representing chewing has enhanced functional connectivity to secondary auditory cortex in response to any kind of sound.

Resting state Functional Connectivity

Using non-invasive fMRI modality, we recorded the metabolic activity of the brain at rest (resting state fMRI) in both Misophonic subjects and matched healthy controls. We found increased functional connectivity during rest in Misophonia subjects than healthy controls between:

  • Secondary interoceptive brain (Left anterior Insula) with Motor brain areas (left Motor cortex and right Cerebellum)

  • Auditory brain (Right Planum Temporale) with the brain area that represents chewing (right Motor cortex)

  • Visual brain (Right V2) with the brain area that represents chewing (right Motor cortex)

  • The brain area that represents chewing (right Motor cortex) with the interoceptive brain (right Insula)

  • Two core nodes of the default mode network (posterior Cingulate Cortex and ventro-medial Pre Frontal cortex)

Interoceptive network

The secondary interoceptive brain area has increased functional connectivity during rest with the motor brain areas in Misophonics than Controls

Auditory brain and Chewing area

The secondary auditory cortex has increased functional connectivity during rest with the brain area that represents jaw, lip, and tongue movement in Misophonics than Controls

Visual brain and Chewing area

Right secondary visual cortex has increased functional connectivity during rest with the brain area that represents jaw, lip, and tongue movement in Misophonics than Controls

Chewing area & Interoceptive network

The brain area that represents jaw, lip, and tongue movement has increased functional connectivity during rest with the secondary auditory cortex as well as interoceptive network in Misophonics than Controls

Core Default Mode Network

Left anterior Insula does not have a differential connectivity with the brain regions that are connected at rest (DMN) though the DMN itself has increased functional connectivity in Misophonics than Controls

Summary

  • Conventionally, Misophonia has been considered as a disorder of sound emotion processing.

  • Here, we propose a model of Misophonia based on involuntary ‘mirroring’ of action of others. Here, trigger sounds / images activate the part of the brain in Misophonia sufferers as if they are executing the movements themselves. This is known as "mirroring".

  • This involuntary overactivation of the 'mirror' system may lead to either a sense of loss of control or interference in current goals and actions of Misophonia sufferers. Thus this results in anger or irritation.

Relevant publication

Sukhbinder Kumar, Pradeep Dheerendra, Mercede Erfanian, Ester Benzaquén, Willam Sedley, Phillip Gander, Meher Lad, Doris-Eva Bamiou, Timothy Griffiths, "The motor basis for Misophonia", Journal of Neuroscience, May 2021, JN-RM-0261-21; DOI: 10.1523/JNEUROSCI.0261-21.2021

Link: https://www.jneurosci.org/content/early/2021/05/20/JNEUROSCI.0261-21.2021