Month: April 2008

Rats’ visual systems made plastic by anti-depressants

Blogging on Peer-Reviewed ResearchMy mind raced for potential titles to a post when I read the recent report from Science, ‘The Antidepressant Fluoxetine Restores Plasticity in the Adult Visual Cortex,’ by a team headed by José Fernando Maya Vetencourt (abstract), but I’ve opted to be demure, rather than go with some of my other options (like ‘Anti-depressants the “Cocoon” pool for brain?’ or something similarly outrageous).

The research team investigated wither fluoxetine, a selective serotonin reuptake inhibitor (SSRI), could restore plasticity in the visual system of adult rats. They chose fluoxetine because long-term regimens of the drug promote neurogenesis and synaptogenesis in the hippocampus and increased activity of neurotrophin brain-derived neurotrophic factor (BDNF) and its primary receptor, TrkB (close paraphrase to the original article). These effects have been shown essential to the drug’s effect; block one of these processes, and the anti-depressant doesn’t work nearly as well. In order to test plasticity, the team studied how rats responded to monocular deprivation — covering one eye — both the initial shift in ocular dominance and then the recovery of visual function after long-term monocular deprivation. In general, the fluoxetine-treated rats responded in exaggerated fashion to both conditions, suggesting that plasticity was greater with long-term administration of the drug. From the abstract:

We found that chronic administration of fluoxetine reinstates ocular dominance plasticity in adulthood and promotes the recovery of visual functions in adult amblyopic animals, as tested electrophysiologically and behaviorally. These effects were accompanied by reduced intracortical inhibition and increased expression of brain-derived neurotrophic factor in the visual cortex. Cortical administration of diazepam prevented the effects induced by fluoxetine, indicating that the reduction of intracortical inhibition promotes visual cortical plasticity in the adult. Our results suggest a potential clinical application for fluoxetine in amblyopia as well as new mechanisms for the therapeutic effects of antidepressants and for the pathophysiology of mood disorders.

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Perception and Politics

Do we really know what’s going on? Or do we just see what we want to see?

The Data

Larry Bartels, director of the Center for the Study of Democratic Politics at Princeton, has an op-ed Who’s Bitter Now? which shows us a stereotype of rural voters in action. His argument? “Small-town people of modest means and limited education are not fixated on cultural issues. Rather, it is affluent, college-educated people living in cities and suburbs who are most exercised by guns and religion. In contemporary American politics, social issues are the opiate of the elites.”

Bartels sets out to actually define the “small-town working class,” making less than $60,000, living in small towns or rural areas, never graduated from college. He compares them to cosmopolitan voters, college graduates who live in the suburbs or cities making $60,000 or more. The first group makes up about 16 percent of voters, the second 13 percent.

Small-town, working-class people are more likely than their cosmopolitan counterparts, not less, to say they trust the government to do what’s right. In the 2004 National Election Study conducted by the University of Michigan, 54 percent of these people said that the government in Washington can be trusted to do what is right most of the time or just about always. Only 38 percent of cosmopolitan people expressed a similar level of trust in the federal government.

Do small-town, working-class voters cast ballots on the basis of social issues? Yes, but less than other voters do. Among these voters, those who are anti-abortion were only 6 percentage points more likely than those who favor abortion rights to vote for President Bush in 2004. The corresponding difference for the rest of the electorate was 27 points, and for cosmopolitan voters it was a remarkable 58 points. Similarly, the votes cast by the cosmopolitan crowd in 2004 were much more likely to reflect voters’ positions on gun control and gay marriage.

Bartels finishes by telling us the larger pattern behind it all. “It is true that American voters attach significantly more weight to social issues than they did 20 years ago. It is also true that church attendance has become a stronger predictor of voting behavior. But both of those changes are concentrated primarily among people who are affluent and well educated, not among the working class.”

The Interpretation

So why the problem in perception? Is it because he clings to a stereotype, as Bartels seems to suggest?

Nicholas Kristof’s column today, Divided They Fall, offers us better than a yes/no. He wants to take on “how our biases shape our understanding of reality.” Of course the candidate you favor won the debate last time… Or did he or she?

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Microtargeting or Macrotargeting? On Politics and Culture

What’s for Dinner? The Pollster Wants to Know sets out a basic anthropological argument—people’s behaviors and traits are not isolated, discrete units, easily analyzed as individual phenomenon. They are linked, interconnected, patterned.

As Kim Severson opens, “If there’s butter and white wine in your refrigerator and Fig Newtons in the cookie jar, you’re likely to vote for Hillary Clinton. Prefer olive oil, Bear Naked granola and a latte to go? You probably like Barack Obama, too. And if you’re leaning toward John McCain, it’s all about kicking back with a bourbon and a stuffed crust pizza while you watch the Democrats fight it out next week in Pennsylvania.”

Voting patterns are linked to eating patterns. Any wonder politicians are always stuffing down the local “delicacies”?

Severson’s article then goes onto discuss microtargeting: “The idea is that in the brand-driven United States, what we buy and how we spend our free time is a good predictor of our politics. Political strategists slice and dice the electorate into small segments, starting with traditional demographics like age and income, then mixing consumer information like whether you prefer casinos or cruises, hunting or cooking, a Prius or a pickup. Once they find small groups of like-minded people, campaigns can efficiently send customized phone, e-mail or direct mail messages to potential supporters, avoiding inefficient one-size-fits-all mailings.”

Karl Rove, President Bush’s ex-adviser, and Mark Penn, Hillary Clinton’s ex-adviser, both practiced microtargeting, looking for those wedge issues. And indeed, that captures one part of the story about everyday life. Local context, social relationships, like-minded people, that’s a powerful way to think about culture. Republicans tend to drink Dr. Pepper, Democrats go for Pepsi.

But Coca-Cola is the American brand, recognized the world around. And Obama’s campaign is aiming for this sort of “macrotargeting.” “The idea is to build a unified, all-encompassing Obama brand that works well across all kinds of media platforms. ‘I would say we’re old-fashioned in that you have to look at America as a whole,’ said Bill Burton, Mr. Obama’s national press secretary.” The larger patterns, the things that unify people across lines of class and gender and race, that’s another powerful way to think about culture too.

Generally these patterns of culture are harder to recognize—people pick up on the daily wedge issues, on the things that make us different. Most social science research is built on this approach. But as Robert LeVine argues in his classic Properties of Culture, this focus on individual variation generally comes at the expense of understanding consensus.

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Why Obama Won Last Night

Today op-ed writers and bloggers alike are going critical on Obama’s performance in last night’s debate.  Like teenagers on OMG (Oh My God!), they say things like, “Like, did you hear what Obama said in the middle?” and “OMG, Hillary had the best put down.”

A basic dictum in anthropology, and much of life, is to pay attention to both what people say and what people do.  And the doing often matters much more.  But today’s critics are all focused on the message, not the medium or even the meta-message.  From the perspective of this neuroanthropologist, Obama won.  Here’s why.

Let’s talk medium.  A nationally televised debate.  And in this debate it is the performance that matters as much as the words said.  Last night for the first time Obama acted presidential, not just inspirational.  “The buck stops here”–that was the most significant moment of the debate.  People want leadership from a president.  Obama showed himself ready.

The whole debate format backed that up, reinforcing a clear but largely unconscious conclusion.  For the first time Clinton said Obama was presidential.  The moderators defered to Obama, even with their challenging follow-up questions–reporters after a leader.  Remember the moderator comment, apologizing to Clinton for Obama speaking more?  All Clinton could comment was, “I noticed.”

In the primate world an avoidant gaze is a mark of submission.  Clinton, time and again, had her eyes wandering around the crowd.  Obama looked directly at the moderators or at the cameras.  The implicit message?  Here’s the leader.

And the meta-message?  Whatever the policy debates and the snipping over verbal gaffes and significant others (OMG! they know people!), Obama had the clearer meta-message.  We need change.  We need to address the broad problems facing all of us.  We need to get past politics as usual.

Why is this important?  Obama, in responding to criticisms, consistently and clearly came back to his meta message, his unifying theme.  Clinton came off as defensive in her meta-message–But I have experience, But I’ve been vetted by Republican attacks.  It was not about leadership.  And it was dispersed, rather than focused.  Focus matters.

What about those spontaneous moments?  Applause, muted and quickly cut off, came for Obama.  People heard that, in the room and on television.  People saw the two candidates’ eyes.  People followed not just the questions, but how the reporters acted.  People got the take-home meta-message.  Context, interactions, behaviors–Obama acted like a winner in a convincing way reinforced by those around him.

Do I agree with all his words?  I don’t know.  I don’t even remember them all.  But I know what I saw.

Testosterone and cortisol explain market behaviour?

There’s a fascinating post on Testosterone, Cortisol and Market Behavior on the website Pure Pedantry. Normally, I’d have a whole lot of caveats and snarky comments to add, but Jake Young does a great job of handling an original research article by Coates and Herbert, ‘Endogenous steroids and financial risk taking on a London trading floor’ (abstract). You should definitely check out Jake’s post if you find this material interesting, as he deals with the article in greater depth. Unlike in my last piece on ‘neuroeconomics’, Bad brain science: Boobs caused subprime crisis, in which I thought the science writer involved was really responsible, in this case, it looks like the authors of the original study are partly to blame, and Young does a good job of highlighting this issue.

The original research paper examines the links between market risk-taking behaviour among traders with endogenous steroids: testosterone and cortisol. Since both are linked to aggression and stress, this would seem to be a good place to study the body’s response to risk taking. But things don’t go brilliantly, as Young suggests: ‘Let’s file this paper under “wildly over-interpreted” because there are some big caveats that you have to remember before you can make a claim anything like [hormone changes lead to market changes and higher market volatility].’

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Antidepressants suppress identity?

Another interesting one from The New York Times, Who Are We? Coming of Age on Antidepressants, by Dr. Richard A. Friedman; I found this one really well done, asking more questions than it answers, but thought-provoking.

The introduction to the article lays out the central existential question posed by long-term treatment with anti-depressants, especially for patients who started on their regimens when very young:

“I’ve grown up on medication,” my patient Julie told me recently. “I don’t have a sense of who I really am without it.”
At 31, she had been on one antidepressant or another nearly continuously since she was 14. There was little question that she had very serious depression and had survived several suicide attempts. In fact, she credited the medication with saving her life.
But now she was raising an equally fundamental question: how the drugs might have affected her psychological development and core identity.

As Friedman points out, the medical testing for these pharmaceuticals doesn’t include long-term research anywhere close to the lengths of time that people are actually spending on the drugs: the longest maintenance study — done on Effexor — lasted two years.

But the more subtle issues that Friedman raises, as far as I’m concerned, are the questions of identity that are clouded by long-term anti-depressant use. He discusses one woman who was concerned about her ‘low sex drive’ and pressure from her boyfriend to have sex after eight years on libido-reducing Zoloft: ‘She had understandably mistaken the side effect of the drug for her “normal” sexual desire and was shocked when I explained it: “And I thought it was just me!”’ I can’t tell from the way Friedman writes this how he feels about the idea that an individual has a ‘normal’ sex drive, something that might exist ‘prior to’ or ‘independent of’ any outside influences, whether that influence be an anti-depressant or a particular life event or the effects of interpersonal dynamics with a partner.

The idea that the ‘anti-depressed’ state might become ‘normal,’ both in the medical sense that intervention seeks to create this state and in the sense that a patient spends so much time in the drug-influenced state that it becomes a kind of reference, suggests yet another way that cultural expectations might become biological ‘nature.’