Saturday, January 12, 2008
MIT researchers and colleagues report in the first brain imaging study of its kind.
Brain activity in East Asians and Americans as they make relative and absolute judgments. The arrows point to brain regions involved in attention that are engaged by more demanding tasks. Americans show more activity during relative judgments than absolute judgments, presumably because the former task is less familiar and hence more demanding for them. East Asians show the opposite pattern.
Culture influences brain function, MIT imaging shows
People from different cultures use their brains differently to solve the same visual perceptual tasks, MIT researchers and colleagues report in the first brain imaging study of its kind.
Psychological research has established that American culture, which values the individual, emphasizes the independence of objects from their contexts, while East Asian societies emphasize the collective and the contextual interdependence of objects. Behavioral studies have shown that these cultural differences can influence memory and even perception. But are they reflected in brain activity patterns?
To find out, a team led by John Gabrieli, a professor at the McGovern Institute for Brain Research at MIT, asked 10 East Asians recently arrived in the United States and 10 Americans to make quick perceptual judgments while in a functional magnetic resonance imaging (fMRI) scanner--a technology that maps blood flow changes in the brain that correspond to mental operations.
The results are reported in the January issue of Psychological Science. Gabrieli's colleagues on the work were Trey Hedden, lead author of the paper and a research scientist at McGovern; Sarah Ketay and Arthur Aron of State University of New York at Stony Brook; and Hazel Rose Markus of Stanford University.
Subjects were shown a sequence of stimuli consisting of lines within squares and were asked to compare each stimulus with the previous one. In some trials, they judged whether the lines were the same length regardless of the surrounding squares (an absolute judgment of individual objects independent of context). In other trials, they decided whether the lines were in the same proportion to the squares, regardless of absolute size (a relative judgment of interdependent objects).
In previous behavioral studies of similar tasks, Americans were more accurate on absolute judgments, and East Asians on relative judgments. In the current study, the tasks were easy enough that there were no differences in performance between the two groups.
However, the two groups showed different patterns of brain activation when performing these tasks. Americans, when making relative judgments that are typically harder for them, activated brain regions involved in attention-demanding mental tasks. They showed much less activation of these regions when making the more culturally familiar absolute judgments. East Asians showed the opposite tendency, engaging the brain's attention system more for absolute judgments than for relative judgments.
"We were surprised at the magnitude of the difference between the two cultural groups, and also at how widespread the engagement of the brain's attention system became when making judgments outside the cultural comfort zone," says Hedden.
The researchers went on to show that the effect was greater in those individuals who identified more closely with their culture. They used questionnaires of preferences and values in social relations, such as whether an individual is responsible for the failure of a family member, to gauge cultural identification. Within both groups, stronger identification with their respective cultures was associated with a stronger culture-specific pattern of brain-activation.
How do these differences come about? "Everyone uses the same attention machinery for more difficult cognitive tasks, but they are trained to use it in different ways, and it's the culture that does the training," Gabrieli says. "It's fascinating that the way in which the brain responds to these simple drawings reflects, in a predictable way, how the individual thinks about independent or interdependent social relationships."
Gabrieli is the Grover Herman Professor of Health Sciences and Technology and Brain and Cognitive Sciences, and holds an appointment at the Harvard-MIT Division of Health Sciences and Technology. This study was funded by the National Institutes of Health and supported by the McGovern Institute.
UCLA researchers show that culture influences brain cells
A thumb’s up for “I’m good.” The rubbing of a pointed forefinger at another for “shame on you.” The infamous and ubiquitous middle finger salute for—well, you know. Such gestures that convey meaning without speech are used and recognized by nearly everyone in our society, but to someone from a foreign country, they may be incomprehensible.
The opposite is true as well. Plop an American in a foreign land and he or she may be clueless to the common gestures of that particular culture. This raises a provocative question—does culture influence the brain"
The answer is yes, reports Istvan Molnar-Szakacs, a researcher in the UCLA Tennenbaum Center for the Biology of Creativity, and Marco Iacoboni, director of the Transcranial Magnetic Stimulation Lab at the Ahmanson-Lovelace Brain Mapping Center of UCLA's Semel Institute for Neuroscience and Human Behavior. Their research appears in the current issue of the journal PLoS ONE and is available online at http://www.plosone.org/doi/pone.0000626.
In their study, the researchers wanted to investigate the imprint of culture on the so-called mirror neuron network. Mirror neurons fire when an individual performs an action, but they also fire when someone watches another individual perform that same action. Neuroscientists believe this "mirroring" is the neural mechanism by which we can read the minds of other people and empathize with them.
When it comes to the influence of culture, they found that indeed, the mirror neuron network responds differently depending on whether we are looking at someone who shares our culture, or someone who doesn’t.
The researcher’s used two actors, one an American, the other a Nicaraguan, to perform a series of gestures--American, Nicaraguan, and meaningless hand gestures, to a group of American subjects. A procedure called transcranial magnetic stimulation (TMS) was used to measure the levels of so-called “corticospinal excitability” (CSE)—which scientists use to probe the activity of mirror neurons.
They found that the American participants demonstrated higher mirror neuron activity while observing the American making gestures compared to the Nicaraguan. And when the Nicaraguan actor performed American gestures, the mirror neuron activation of the observers dropped.
“We believe these are some of the first data to show neurobiological responses to culture-specific stimuli,” said Molnar-Szakacs. “Our data show that both ethnicity and culture interact to influence activity in the brain, specifically within the mirror neuron network involved in social communication and interaction.”
“We are the heirs of communal but local traditions,” said Iacoboni. “Mirror neurons are the brain cells that help us in shaping our own culture. However, the neural mechanisms of mirroring that shape our assimilation of local traditions could also reveal other cultures, as long as such cross-cultural encounters are truly possible. All in all, our research suggests that with mirror neurons our brain mirrors people, not simply actions.”
Thus, it appears that neural systems supporting memory, empathy and general cognition encodes information differently depending on who’s giving the information—a member of one’s own cultural/ethnic in-group, or a member of an out-group, and that ethnic in-group membership and a culturally learned motor repertoire more strongly influence the brain’s responses to observed actions, specifically actions used in social communication.
“An important conclusion from these results is that culture has a measurable influence on our brain and, as a result, our behavior. Researchers need to take this into consideration when drawing conclusions about brain function and human behavior,” said Molnar-Szakacs. The findings, the researchers note, may also have implications for motor skill and language learning, intergroup communication, as well as the study of intergroup attitudes toward other cultures. Source : University of California - Los Angeles.
Posted by SANJIDA AFROJ at 9:14 PM