Using brain scans carried out with Magnetic resonance imaging (MRI) the team revealed a physical difference in the frontal lobe between the cerebral hemispheres of people with misophonia - with higher myelination in the grey matter of ventromedial prefrontal cortex (vmPFC).
The study also used functional MRI to measure the brain activity of people with and without misophonia while they were listening to a range of sounds such as;
Rain, busy café, a kettle boiling – neutral sounds
Baby crying, a person screaming – unpleasant sounds
The sounds of breathing, eating – trigger sounds
This showed abnormal connections between this frontal-lobe area and an area called the anterior insular cortex (AIC). This area is in the grey matter of the brain but buried in a deep fold at the side of the brain and is known to be involved in processing emotions and integrating signals both from the body and outside world.
When presented with trigger sounds activity goes up in both areas in misophonic subjects, whilst in normal subjects the activity goes up in the AIC but down in the frontal area. The team think that this reflects an abnormality of a control mechanism between the frontal lobe and AIC.