Category: Brain imaging

Thinking about how others think: two ways?

Blogging on Peer-Reviewed ResearchJason Mitchell and Mahzarin R. Banaji, of Harvard University, and C. Neil Macrae, at the University of Aberdeen, published a fascinating piece in Neuron in May 2006, ‘Dissociable Medial Prefrontal Contributions to Judgments of Similar and Dissimilar Others’ (abstract on PubMed or pdf download here). I came across the article through the Mind Matters blog in a piece by Stephen Macknik (director of the Laboratory of Behavioral Neurophysiology at the Barrow Neurological Institute in Phoenix), entitled How Harvard students perceive rednecks: The neural basis for prejudice. Both the original article and the blog post by Macknik are worth checking out.

In the experiment, the team headed by Mitchell showed the subjects photographs and asked the subjects questions about the beliefs, feelings, or attitudes of the people in the pictures. Subjects were told the pictures were of either ‘liberal northeastern’ or ‘conservative Midwest fundamentalist Christian students’ after doing a survey which determined which group the subjects were most like. The categories for the photographs were false, the pictures being taken from dating websites and randomly assigned to either of the groups. The photos were reassigned for each subject, and gender, age and other distinguishing marks controlled for (or likely just avoided by the original choice of photos). In other words, college students were being told that other ‘college students’ were either ‘like them’ or ‘different from them,’ with (apparently) no visual cues for either identity. The research team was interested in what parts of the brain were being used in attempts to ‘mentalize,’ that is, to perceive the thoughts, motives or perceptions of others.

In particular, the researchers discussed that slightly different parts of the medial prefrontal cortex (mPFC) are used when trying to mentalize, depending upon whether the target of observation is believed to be similar or dissimilar (should I write ‘the Other’ to prove I’m a cultural anthropologist?) to the self. Specifically, a more ventral (front) part of mPFC is used when ‘mentalizing’ about others perceived as similar, as opposed to a higher (dorsal) part of the mPFC used to deduce the thinking or feelings of others when confronted with photos of people thought to be ‘unlike’ themselves. The difference is significant because the different regions suggest that these perceptions are being accomplished in distinct fashion.

… simulation theories of social cognition suggest that this [ventral] region should be specifically engaged for mental state inferences about others perceived to be similar to oneself, since mentalizing on the basis of self knowledge can only take place if another person’s internal experience is assumed to be comparable to one’s own. As such, this hypothesis suggests an important ‘‘division of labor’’ in the contributions made by different subregions of mPFC to mentalizing. Whereas ventral mPFC may be expected to contribute to mental state inferences about similar others, the dorsal [upper or top] aspects of mPFC—more traditionally associated with mentalizing tasks—should be specifically engaged by mentalizing about dissimilar others, that is, individuals for whom overlap between self and other cannot be assumed.

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Auditory neurons learning to hear

The Biotechnology and Biological Sciences Research Council’s recent business report (January 2008) had an interesting research report on auditory neurons and the perception of complex sounds. (Science Daily has a short report on the longer piece available here). (The BBSRC is the UK’s principal funder of basic biological research.)

As the BBSRC piece discusses, sound perception is extremely difficult because similar objects often make quite different sounds, and the medium (typically air) through which we hear does not allow for the spatialization or easy decomposition that, say, light allows in vision. The Oxford-based research team is using neural imaging to try to figure out how the brain makes sense of sound, and one thing that they’re finding is that background noise appears to be extremely important to sound processing. The auditory cortex does not simply respond to isolated qualities of specific sounds but to variations in the statistical properties of the entire sound scape. As the article reports: ‘Cortical neurons appear to anticipate this particular level of statistical regularity, and respond best to sounds that vary in pitch and intensity according to this natural rate of ebb and flow, which is found in many natural scenes and most musical compositions.’

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Visual Rewards

Blogging on Peer-Reviewed ResearchWhy will we study a favored painting again and again?  Or gaze on our lover’s face with such pleasure, even after years and lines have mounted?

 I came across an article, “Perceptual Pleasure and the Brain,” by Irving Biederman and Edward Vessel in American Scientist.  They studied the distribution of mu-opioid receptors, associated with the modulation of pleasure and pain, in the visual cortex.  Their basic result: “The receptors are sparsest in the early stages of this [central visual] pathway, the so-called V1 to V4 areas, where an image is processed as local bits of contour, color and texture.  Intermediate stages of visual processing, such as the lateral occipital area and ventral occipito-temporal cortex, which integrate local information to detect surfaces, objects, faces and places, contain greater number of opioid receptors.  The receptors are densest in the later stages of recognition, in the parahippocampal cortex and rhinal cortex, where visual information engages our memories.”

 Thus, they argue, “a visual stimulus that elicits many episodic or semantic memories should be more pleasing (or more interesting) than a stimulus that brings forth fewer mental associations.” 

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Puzzles and Cultural Differences

Blogging on Peer-Reviewed ResearchHere’s some interesting research where neuroscientists are using brain scans to show that cultural differences reach down to the level of functional activation in the brain.  Americans had a harder time with visual puzzles that required manipulating objects in context than “East Asians.”  Here a quote from the news article:

 

Neuroscientists Trey Hedden and John Gabrieli of MIT’s McGovern Institute for Brain Research asked Americans and East Asians to solve basic shape puzzles while in a functional magnetic resonance imaging (fMRI) scanner. They found that both groups could successfully complete the tasks, but American brains had to work harder at relative judgments, while East Asian brains found absolute judgments more challenging. Previous psychology research has shown that American culture focuses on the individual and values independence, while East Asian culture is more community-focused and emphasizes seeing people and objects in context. This study provides the first neurological evidence that these cultural differences extend to brain activity patterns.

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Why We Love, The Time Magazine Version

Too bad Jeffrey Kluger didn’t pay closer attention to Hannibal Lecter.  He might have written a better article on “Why We Love,” out this week in Time Magazine, instead of giving us a flawed view of evolution and brain research.  Still, in furtive glimpses of data, rather than quick quotes and pop theories, another way to think about love glides onto stage. 

As I told my anthropology students yesterday, the initial assumptions we make so often dictate our ideas and our results.  But those assumptions are generally presented as “facts” or assertions of truth, part of an unassailable background.  So here are the ones packed into Kluger’s piece, right there at the beginning: (1) that humans rely on our wits, so “losing our faculties over a matter like sex” needs explaining (in other words, humans are rational, why have primitive passions); (2) that we evolved in a “savanna full of predators,” so getting distracted by love could be potentially dangerous, (3) that our genes have “concerns,” primary among them to make us reproduce as much as possible (“breed now and breed plenty gets that job done”), and (4) that we can extend these sorts of explanations to all “the rituals surrounding” sex, love and relationships (like a bunch of scientists drunk on their own ideas—explanatory expansion gone wild!). 
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Steven Pinker and the Moral Instinct

By Daniel Lende 

Steven Pinker is selling something.  Here’s what’s on the table: “the human moral sense turns out to be an organ of considerable complexity.”  This organ has been built into our brains by evolution, culture-free except for how its five domains (harm, fairness, community, authority, and purity) are “ranked” and “channeled” in different places around the globe.  Ready to buy? 

Let’s sweeten the deal.  Pinker is offering his “deeper look” which will help you “rethink your answers” about life and morality.  He’s providing “a more objective reckoning” to help people get over their moral “illusions.”  And he’s got the data to show it, from people in the lab, Web sites, and brain scanners.  (I can’t help asking, these are his moral examples?  People in artificial situations, people who don’t physically interact, and a series of images?)  Continue reading “Steven Pinker and the Moral Instinct”