What is happiness, and how do we find it? There are 93,290 books on happiness at Amazon.com. Happiness is Life's Most Important Skill, an Advantage and a Project and a Hypothesis that we can Stumble On and Hard-Wire in 21 Days.
The Pursuit of Happiness is an Unalienable Right granted to all human beings, but it also generates billions of dollars for the self-help industry.
And now the search for happiness is over! Scientists have determined that happiness is located in a small region of your right medial parietal lobe. Positive psychology gurus will have to adapt to the changing landscape or lose their market edge. “My seven practical, actionable principles are guaranteed to increase the size of your precuneus or your money back.”
The structural neural substrate of subjective happiness is the precuneus.A new paper has reported that happiness is related to the volume of gray matter in a 222.8 mm3 cluster of the right precuneus (Sato et al., 2015). What does this mean? Taking the finding at face value, there was a correlation (not a causal relationship) between precuneus gray matter volume and scores on the Japanese version of the Subjective Happiness Scale.1
Fig. 1 (modified from Sato et al., 2015). Left: Statistical parametric map (p < 0.001, peak-level uncorrected for display purposes). The blue cross indicates the location of the peak voxel. Right: Scatter plot of the adjusted gray matter volume as a function of the subjective happiness score at the peak voxel. [NOTE: Haven't we agreed to not show regression lines through scatter plots based on the single voxel where the effect is the largest??]
“The search for happiness: Using MRI to find where happiness happens,” said one deceptive headline. Should we accept the claim that one small region of the brain is entirely responsible for generating and maintaining this complex and desirable state of being?
NO. Of course not. And the experimental subjects were not actively involved in any sort of task at all. The study used a static measure of gray matter volume in four brain Regions of Interest (ROIs): left anterior cingulate gyrus, left posterior cingulate gyrus, right precuneus, and left amygdala. These ROIs were based on an fMRI activation study in 26 German men (mean age 33 yrs) who underwent a mood induction procedure (Habel et al., 2005). The German participants viewed pictures of faces with happy expressions and were told to “Look at each face and use it to help you to feel happy.” The brain activity elicited by happy faces was compared to activity elicited by a non-emotional control condition. Eight regions were reported in their Table 1.
Table 1 (modified from Habel et al., 2005).
Only four of those regions were selected as ROIs by Sato et al. (2015). One of these was a tiny 12 voxel region in the paracentral lobule, which was called precuneus by Sato et al. (2015).
Image: John A Beal, PhD. Dept. of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center Shreveport.
Before you say I'm being overly pedantic, we can agree that the selected coordinates are at the border of the precuneus and the paracentral lobule. The more interesting fact is that the sadness induction of Habel et al. (2005) implicated a very large region of the posterior precuneus and surrounding regions (1562 voxels). An area over 100 times larger than the Happy Precuneus.
Oops. But the precuneus contains multitudes, so maybe it's not so tragic. The precuneus is potentially involved in very lofty functions like consciousness and self-awareness and the recollection of autobiographical memories. It's also a functional core of the default-mode network (Utevsky et al., 2014), which is active during daydreaming and mind wandering and unconstrained thinking.
But it seems a bit problematic to use hand picked ROIs from a study of transient and mild “happy” states (in a population of German males) to predict a stable trait of subjective happiness in a culturally distinct group of younger Japanese college students (26 women, 25 men).
Cross-Cultural Notions of Happiness
Isn't “happiness” a social construct (largely defined by Western thought) that varies across cultures?
Should we expect “the neural correlates of happiness” (or well-being) to be the same in Japanese and Chinese and British college students? In the Chinese study, life satisfaction was positively correlated with gray matter volume in the right parahippocampal gyrus but negatively correlated with gray matter volume in the left precuneus... So the participants with the largest precuneus volumes in that study had the lowest well-being.
What does a bigger (or smaller) size even mean for actual neural processing? Does a larger gray matter volume in the precuneus allow for a higher computational capacity that can generate greater happiness?? We have absolutely no idea: “...there is no clear evidence of correlation between GM volume measured by VBM and any histological measure, including neuronal density” (Gilaie-Dotan et al., 2014).
Sato et al. (2015) concluded that their results have important practical implications: Are you happy? We don't have to take your word for it any more!
In terms of public policy, subjective happiness is thought to be a better indicator of happiness than economic success. However, the subjective measures of happiness have inherent limitations, such as the imprecise nature of comparing data across different cultures and the difficulties associated with the applications of these measures to specific populations, including the intellectually disabled. Our results show that structural neuroimaging may serve as a complementary objective measure of subjective happiness.
Finally, they issued the self-help throw down: “...our results suggest that psychological training that effectively increases gray matter volume in the precuneus may enhance subjective happiness.”
Resting-state functional connectivity of the default mode network associated with happiness is so last month...
Are You Conscious of Your Precuneus?
Be nice to your Precuneus – it might be your real self…
Your Precuneus May Be the Root of Happiness and Satisfaction
The Precuneus and Recovery From a Minimally Conscious State
1 The Subjective Happiness Scale is a 4-item measure of global subjective happiness (Lyubomirsky & Lepper, 1999).
Habel, U., Klein, M., Kellermann, T., Shah, N., & Schneider, F. (2005). Same or different? Neural correlates of happy and sad mood in healthy males NeuroImage, 26 (1), 206-214 DOI: 10.1016/j.neuroimage.2005.01.014
Sato, W., Kochiyama, T., Uono, S., Kubota, Y., Sawada, R., Yoshimura, S., & Toichi, M. (2015). The structural neural substrate of subjective happiness Scientific Reports, 5 DOI: 10.1038/srep16891
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