Stanford University researchers have suggested that a lack of response to emotionally meaningful information in the insula, a brain region at the hub of the salience network, can lead to a cascade of effects that result in inappropriate emotional displays.

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Activity was also elevated in the insula, a region that monitors one's emotional and physical state (it's also involved in disgust, shame and other strong negative emotions).

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The reason for this, the UCLA life scientists found, seems to be that a brain region called the anterior insula, which is linked to disgust and is important for discerning untrustworthy faces, is less active in older adults.

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They discovered that when people are offered an unfair split, a primal part of their brains known as the anterior insula sends out signals of disgust and anger.

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