25 October 2007

Optimism and the Brain

A recent study in Nature suggests that a sense of optimism about the future may depend upon at least two brain centers--the amygdyla and the rostral Anterior Cinculate Cortex (rACC).
Brain scans obtained using functional magnetic resonance imaging (fMRI) revealed that reflecting on both past and future events activated the amygdala and the (rACC) areas, both of which sit deep in the middle of the brain. However, positive events – and particularly those imagined in the future – elicited a significantly bigger brain response in these regions than reflecting on negative events.

Tali Sharot, a co-author of the new study now based at the University College London, UK, notes that the more pessimistic subjects in the trial had less activation of these brain areas than their optimistic counterparts when imagining happy events.

All this has led the researchers to suspect that the amygdala and rACC play an important role in signalling cheerful thoughts.

Wayne Drevets, a scientist at the National Institute of Mental Health in Bethesda, Maryland, US, says that the results represent a departure from "a long-term fad where people would only talk about the amgydala [and rACC] in terms of negative emotions".

"What's striking is that these appear to be the same areas implicated in depression," says Phelps. Previous research has suggested that patients with depression have decreased nerve signalling in the rACC and amygdala.

Drevets notes that autopsies performed on severely depressed patients found fewer cells than normal in the rACC and amygdala. He says the new findings from Phelps’s study could perhaps explain why people with depression often have an absence of positive thoughts.
New Scientist

Intriguingly, the size of this region of ACC seems to be associated with the sense of personal social status and, also, health and lifespan.
In their paper, Gianaros and colleagues (2007) used structural neuroimaging techniques to investigate, whether certain neural regions vary in size as a function of "perceived social standing," a self-report measure that captures the subjective perception of being lower in social status. Participants were shown an image of a 10-rung ladder and were asked to mark the rung that corresponds to where they think, they ‘stand’ compared to others in the United States based on income, education and occupational status. The authors found that self-reported social status correlated with gray matter volume in only one region in the entire brain, the perigenual anterior cingulate cortex (pACC). Specifically, low perceived social status was associated with reduced gray matter volume in the pACC. These findings remained significant after controlling for demographic, psychological (e.g. depressive symptoms, recent life stress) and conventional SES measures (e.g. income, education).

It is logical to expect someone with high self-perceived social status to feel relatively optimistic about life, and to reap whatever health benefits derive from that optimism.

Certainly the role played by the amygdyla and the rACC in both depression and optimism will require more clarification and elaboration. At this stage in development, neural imaging techniques are more seminal in the generation of excellent questions and hypotheses, than in the answering of questions and conclusive testing of hypotheses. With time, imaging will become better at doing both.

Next question: If a person with low self-perceived status experiences unexpected success--to the point that his self-assessment of status becomes quite high--will his rACC gray matter grow as large as the person who had always self-assessed "high" in status?

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Blogger AntiCitizenOne said...

> If a person with low self-perceived status experiences unexpected success--to the point that his self-assessment of status becomes quite high--will his rACC gray matter grow as large as the person who had always self-assessed "high" in status?

Depression doesn't work like that.

Friday, 26 October, 2007  
Blogger al fin said...

Fair enough. But just how does depression work? Unexpected success will not be enough for some people to "snap out of" their depression. But success that is worked for and sustained may lead to "plasticity" of the gray matter of the rostral anterior cingulate cortex--more gray matter. Not everyone who is clinically depressed is clinically depressed for life.

Current behavioural and cognitive therapies for depression--as well as pharmacological therapies--are mere stopgap therapies until neuroscientists understand why so many people get stuck on the treadmill of depressive thoughts and depression-sustaining habits.

Although, I must admit that the generation of new neurons and synapses from some "effective" depression therapies suggests not only the dynamic nature of the depression spectrum, but possible avenues of research for more long term effective therapies.

Saturday, 27 October, 2007  
Blogger AntiCitizenOne said...

When you are depressed you are not able to identify with personal success.

It would be thus hard to snap out of it.

Sunday, 28 October, 2007  

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