Do introverts have physically different brains?

Some differences have been reported, but the evidence is thin. A 2012 MRI study of 32 men found introverts had more grey matter in parts of the right prefrontal cortex and temporo-parietal junction, regions tied to inhibition and introspection. A 1999 PET study found higher blood flow in frontal regions in introverts. Samples are small, and a 2025 review found no consistent anatomical map of extraversion.

Source: Forsman et al. (2012), Neuroscience Research; Johnson et al. (1999), American Journal of Psychiatry