Does your personality get on everyone’s nerves? Blame your white matter.

Scientists from Yale report correlating white integrity with personality:  Xu J, Potenza MN. White matter integrity and five-factor personality measures in healthy adults. Neuroimage. 2011 Aug 2.

This has to do with brain wiring — we previously nominated the brain wiring diagram is an idea likely to change the world. (Here).  This topic gets a little too quantitative for us, but in general, one must be down with the premise of systems analysis:

. . .It has been found that cortico-cortical networks display a few prominent characteristics: (i) modular organization, (ii) abundant alternative processing paths, and (iii) the presence of highly connected hubs.. . .

Gorka Zamora-López, G.,Changsong, Z., and Jürgen K., “Exploring brain function from anatomical connectivity,” Frontiers in Neuroscience, FOCUSED REVIEW published: 21 June 2011 doi: 10.3389/fnins.2011.00083

Brain connectivity, from a systems perspective, is modular, redundant, and has highly-connected hubs. Just like BART. Except with cell phone service. And so, where white matter is wobbly (having more diffusion detected according to diffusion tensor imaging, having something to do with deflection of water or something, we don’t really understand) the connection is wobbly. Why this  is so can be for any number of reasons — like injury or perhaps globally a channelopathy (one of our pet theories, particularly with calcium channelopathies).  Genetics having to do with white matter development and plasticity also play a role, apparently.

Let’s go through this abstract line by line in conjunction with the White Matter Atlas:

The five-factor model organizes personality traits into five factors: Neuroticism, Extraversion, Openness to Experience, Agreeableness, and Conscientiousness. Measures of these personality traits predict people’s behaviors and important outcomes of their lives. Therefore, understanding the neural correlates of these personality traits is important. This study assessed the relationships between white matter (WM) integrity and personality traits among 51 healthy participants using diffusion tensor imaging (DTI) and the revised NEO Personality Inventory (NEO-PI-R).

A standardized personality assessment combined with white matter imaging. Sounds good.

. . . Neuroticism correlated positively while Openness and Agreeableness correlated negatively with DTI mean diffusivity (MD) in the corona radiata and superior longitudinal fasciculus, tracts that interconnect prefrontal cortex (PFC), parietal cortex, and subcortical structures.

This is interesting. These areas aren’t particularly associated with psychopathy as a whole (blogged here, for instance), consistent with research that psychopaths don’t always show neuroticism. (Blogged here). The superior longitudinal  fasciculus is shown in yellow (click to enlarge):

The unciate fasciculus is shown in red below (click to enlarge).  The UF on the right hand side is wobbly in psychopaths.

To continue:

. . . Furthermore, Neuroticism correlated positively with MD in the anterior cingulum and uncinate fasciculus, tracts interconnecting PFC and amygdala.

This is surprising — neuroticism is associated with a wobbly UF.  Psychopaths have a wobbly uncinate fasciculus on the right hand side.  Perhaps there is a threshold effect, like you need both sides to have structural deficits to be neurotic, but only one side for psychopathy. But that still doesn’t explain why neurosis isn’t particularly correlated with psychopathy.  So here’s a paper:  what is it about psychopath uncinate fasciculus white matter on a cellular level that results in the microstructural deficits? Again our vote is something like a cellular condition, and, because channelopathy is our hammer, it looks like a calcium nail, to torture a metaphor.

As to the anterior cingulum, we wonder if this relates to perception. (See our post on the Uncanny Valley). The anterior cingulum is located near the eyes. Wobbly white matter in the anterior cingulum reportedly is associated with schizophrenia and bipolar disorder (here’s a slide show), as well as Alzheimer’s (here).  What strikes us is the paranoia/apathy associated with these conditions.  One thing we notice about paranoids, (n=1 or 2) is that they operate on the faulty premise, “Because you obviously are getting ready to attack us, we took the liberty of doing something nasty to you in advance.” Are white matter microstructural deficits a biological basis of a hostile attributional bias?

And more:

. . . Openness correlated negatively with MD of WM adjacent to the dorsolateral PFC in both hemispheres. These findings suggest that greater Neuroticism associates with worse integrity of WM interconnecting extensive cortical and subcortical structures including the PFC and amygdala and that greater Openness associates with better integrity of WM interconnecting extensive cortical and subcortical structures including the dorsolateral PFC. . . .

Well then. Suspicions confirmed: The better the white matter integrity and brain module interconnectivity, the less people find you annoying. (We overstate the conclusions, of course.)

Social implications are interesting: Perhaps people will self-segregate based on white matter integrity, with those who do not like change (Amish? political conservatives?) making communities, and the rest of the population freely intermixing.

And, how can anyone recommend those awful color-coded four letter personality tests that HR departments love? Is administering those some kind of HR malpractice?