The Principal Investigator

A recent paper from a consortium including researchers from the National Institute of Mental Health (NIMH), the Lieber Institute on Brain Development, and Johns Hopkins documents the DNA methylation pattern in the human prefrontal cortex across the lifespan. At first glance this article seems exceedingly technical and not of general interest. Now I may be biased because I study a disease (schizophrenia) with significant developmental aspects, but I believe this paper is full of incredible, novel findings on gene expression. The main points of this paper are concepts that we all should be concerned with. It gets to the crux of the age-old nature vs. nurture argument.

The study generally deals with a relatively new field of study known as epigenetics. Epigenetics deals with changes in gene expression, some potentially heritable, that do not include changes to the underlying DNA sequence. This particular article is concerned with DNA methylation. Long story short, DNA methylation leads to the silencing genes and subsequently less mRNA and protein produced by the silenced gene. More genes are silenced as we age. This makes since as development and growth, both physical and mental, should require the products of a greater number of genes. Interestingly, genes that become silenced as we age consist of many many integral players in what we consider “aging.” These include tumor suppressors and DNA repair genes.

We know that environmental experience can lead to epigenetic alterations that affect gene expression. For example, we know that maternal attention (licking, grooming, etc.) leads to epigenetic changes that facilitate anxiolytic responses in the offspring. This finding gets me to the title of this post: How much of what we now call environmental factors actually exert their effect through changes in gene expression. Potentially long-lasting changes in gene expression. I wonder how many experiences that we think are in our past, both positive and negative, that are still with us epigenetically?

Researchers from NYU and UCLA have identified an interesting neurocognitive feature that appears to separate liberals and conservatives. They report that self-described liberals (based on their 2004 choice for President and self-rating on a 10-point liberal-conservative continuum) show better performance on a Go/No-Go and greater activity in the anterior cingulate cortex (ACC) during trials in which an error occurred. The authors conclusions from this study can be summed up by this excerpt:

Stronger conservatism (versus liberalism) was associated with less neurocognitive sensitivity to response conflicts. At the behavioral level, conservatives were also more likely to make errors of commission.

Essentially, the authors are asserting that conservatives have a more rigid cognitive style that makes it more difficult to alter habitual responses when the circumstances require a change in behavior. On the surface, for those of us who have lived through the Bush Administration, this assertion seems plausible maybe even irrefutable. However, there is a lot more sizzle than substance to this paper and I was surprised to see it in Nature Neuroscience in its current form.

Breakdown:

Journal: Nature Neuroscience

Title: Neurocognitive correlates of liberalism and conservatism

Authors: David M. Amodio, John T. Jost, Sarah L. Master and Cindy M. Yee

Subjects: Humans (non-invasive techniques)

Experimental Techniques:
1) Survey questions

2) Electroencephalographic recordings (scalp recordings of the pooled electrical activity of a group of cortical neurons)

Behavioral Measures:
1) Self-rating on a 10-point political ideology scale (-5 to 5). -5 = most liberal
and 5 = most conservative.

2) Go/No-Go Task: An “M” or “W” was displayed on a computer monitor. For half of the participants “M” was the Go symbol and “W” was the No-Go symbol. This means that when the “M” appears the subject was press a button within a certain amount of time after the letter is removed from the screen. The letter is only present for 100 milliseconds (ms) and the subject has only 500 ms to make a response. If “W” is presented the subject must refrain from responding. The Go to No-Go ratio is 4:1 which, along with the short time interval in which to make a decision, serves to bias the responses towards Go. The other half the participants had “W” as the Go signal and “M” as the No-Go signal.

Study Critique:
Pros: This is an interesting attempt to identify the underlying neural components
of an extremely important cultural phenomenon. Political ideology serves to literally govern our interactions with other humans and there is very little known about what is involved in shaping our political values. The researchers show a correlation (although relatively weak) between political views and accuracy on No-Go trials (stronger liberalism = better performance). They also show a correlation between anterior cingulate cortex activity and behavioral accuracy on these No-Go trials with stronger liberalism correlating with increased cingulated activity.

Cons: This report was unable to address any cause/effect aspects of this
phenomenon. For instance, do these differences in the neural activity lead the subjects to find the traditionally “conservative” or “liberal” ideas more appealing or would the pattern of brain activity change along with a change in ideology? It would have been interesting to see if the researchers could have found a task on which more conservative subjects exhibit greater accuracy. Also, other than the fact that the subjects were all right-handed, no other information about the subjects is given. It’s impossible to determine what confounds may be inherent to the study population. Finally, the anterior cingulate cortex appears to be involved in a large array of cognitive functions, however, there is no discussion of other possible explanations beyond alterations in “conflict-related activity.”

Conclusions: This article is a good jumping off point for research into this area. It is also highly controversial given the current political environment. Hopefully, this exposure will lead to more in-depth and insightful research on the topic of what I am going to call Political Neuroscience.

Neurocognitive correlates of liberalism and conservatism (Nature Neuroscience)