The neurological basis of personality has always been a bit of a mystery but researchers are now one step closer to understanding it. Using advanced brain scan technology, researchers were able to estimate myelination levels in different brain areas.

So what exactly is myelin? Myelin is a fatty substance that insulates nerve fibres in your brain. It speeds up information processing and it’s usually thicker in cortex areas related to perception and movement. The process of coating nerve fibres, also known as axons, with myelin is called myelination. Myelination helps protect and conduct electrical signals in the neuron.

Over 1000 young men and women around the age of 29 took personality tests tapping into the Big Five traits and based on their brain scans, it was found that personality traits that are seen as more advantageous such as conscientiousness and emotional stability, may benefit from enhanced myelination in specific areas of the brain during development. These brain areas are where the myelination process is prolonged and continues through adolescence and into your twenties.

Throughout the sample size (1000 brain scans), researchers noticed a pattern where myelination occurred through the cortex. Myelination was thicker in motor and sensory cortices and lighter in the frontal and parietal areas. Frontal and parietal regions support high order mental functions and while myelination appeared lighter, the process was longer.

In addition, researchers found several links between personality traits and myelination:

1) Lower emotional stability (i.e. higher neuroticism) correlated with less myelination in the prefrontal cortex, a brain region involved in emotional control

2) Higher agreeableness correlated with greater myelination in orbitofrontal cortex, specifically in the anterior region which is implicated in prosocial behaviour

3) Higher conscientiousness correlated with greater myelination in part of the prefrontal cortex which is associated with the human conscience

It seems as though traits considered more advantageous are associated with greater myelination but it’s more complicated than that. The study found that higher conscientiousness and higher trait openness were correlated with less myelination in a frontal brain area called the anterior cingulate cortex, an area involved in monitoring mistakes. In addition, greater neuroticism was correlated with more myelination in the occipital lobe.

The findings from this study improves our understanding of personality through a neurobiological standpoint. In the future, it would be interesting to investigate how personality traits and myelination patterns vary over time and see how factors such as diet, genes, and education may influence these patterns.

Toschi, N., & Passamonti, L. (2018). Intra-cortical myelin mediates personality differences. Journal of Personality. doi:10.1111/jopy.12442

https://digest.bps.org.uk/2019/01/08/people-with-advantageous-personality-traits-have-more-nerve-fibre-insulation-myelination-in-key-brain-areas/