Interoception
in 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.

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Interoception concerns with the ability of the brain to receive, integrate, process, be aware of the physiological signals from the body like heart beat, breathing, etc. We hypothesise that interoceptive abilities are different in Misophonia subjects than healthy controls.

To assess brain basis underlying interoception, we recorded the metabolic activity of the brain, using non-invasive fMRI modality, in both Misophonia subjects and matched healthy controls during two tasks: first an interoceptive task of heart beat counting, and second, an sensory task of counting visual gratings.

Brain Activity

We analysed the brain activity during interoceptive and sensory tasks, and found that:

  • In Misophonics, the change in the brain activity within the secondary interoceptive brain (Left Anterior Insula) between an interoceptive (heart beat counting) task vs sensory (visual) tasks is different from those seen in healthy controls.

Brain activity

In Misophonics, the change in the brain activity within the secondary interoceptive brain (Left Anterior Insula) between an interoceptive (heart beat counting) task vs sensory (visual) tasks is different from those seen in healthy controls.

Connectivity during Interoception

During an interoceptive task, the primary interoceptive brain region increases its connectivity with the secondary interoceptive brain region while decreasing with the sensory regions.

Connectivity in Misophonics

In Misophonics, the change in the functional connectivity within the interoceptive brain between an interoceptive vs sensory tasks is different from those seen in healthy controls.

Functional Connectivity

We analysed the functional connectivity during interoceptive and sensory tasks in Misophonia subjects and controls, and found that:

  • During heart beat counting (interoceptive) task, the primary interoceptive brain area (Left Posterior Insula) region increases its functional connectivity with the secondary interoceptive brain area (Right Anterior Insula) while decreasing its connectivity with the sensory regions (visual occipital cortex).

  • Further, this change in the functional connectivity within the interoceptive brain (Insula) between an interoceptive task (heart beat counting) vs sensory task (visual) is different in Misophonia subjects compared to those seen in healthy controls.

Heart Rate variability and Functional Connectivity

A good variability in heart rate is important physiologically. We observed reduced heart rate variability in Misophonics compared to controls. This was found by evaluating RMSSD, the variation in the change in the inter-beat-interval.

This physiological variable was positively correlated with resting state functional connectivity between left anterior Insula and motor cortex (SMA) in Misophonics while negatively correlated in matched healthy controls.