Genes, Culture and Aging

The study of genetics is becoming ever more interesting. Not only have we gone well beyond the nature/nurture debate, but also there is more and more interest in genetic influences on culture and vice versa: the way in which culture impacts gene expression. It is also clear that our brains are amazingly plastic: nutrition, emotional environment, education and experience all impact brain development.

Now it appears that culture does indeed affect the brain.

Westerners and East Asian people process visual information differently: Westerners preferentially process objects, while Asians tend to pay more attention to contextual information. In studies of semantic organization, Asians associate pictures based on functional relationships, for instance grouping together a mother and her child based on maternal relationship. Westerners based their associations on physical features and categorical membership, such as grouping together a woman and a man because they are adults. These differences may be changing as young people in Asian cultures are becoming more westernized.

New research has found that the aging brain reflects cultural differences in the way that it processes visual information. This study “Age and culture modulate object processing and object-scene binding in the ventral visual area” is published this month in the journal Cognitive, Affective & Behavioral Neuroscience. This paper (which can be downloaded here) and another published by the same group in 2006 are the first to demonstrate that culture can alter the brain’s perceptive mechanisms.

The research is the result of a collaboration between Denise Park’s group from the University of Illinois and Michael W. Chee, of the Cognitive Neuroscience Laboratory, SingHealth, in Singapore. The researchers conducted an array of cognitive tests on study subjects at their facilities in the U.S. and Singapore, and used identical functional Magnetic Resonance Imaging (fMRI) scanners at both sites. Their analysis involved 37 young and old East Asians, and 38 young and old Westerners. They found significant cultural differences in how the older adults’ brains responded to visual stimuli.

As Professor Park said,

“These are the first studies to show that culture is sculpting the brain. The effect is seen not so much in structural changes, but at the level of perception.”

We have known for decades that East Asians and Westerners process visual information differently. A paper in 1972 reported that East Asians are more likely to pay attention to the context and relationships in a picture than are Westerners, who more often notice physical features or groupings of similar subjects.

More recent research, which analyzed the eye movements of East Asians and Westerners viewing identical images, found that Westerners were more attentive to central, or dominant, objects, while East Asians paid more attention to the background, or scene.

Last year the team reported differing patterns of neural activation in the brains of East Asians and Americans shown identical pictures. The Americans showed more activity in brain regions associated with object processing than the East Asians, whose brains showed more activity in areas involved in processing background information.

The new study takes this work further, comparing neural responses to visual stimuli in young and old adults in both cultures. These are some of the pictures they used in the experimenets:

The researchers found that all four groups – young and old East Asians; young and old Americans – processed background information in part of the brain called the parahippocampal gyrus: a region that is vital to memory encoding and retrieval. As expected, older adults in both cultures had less ability to use “binding mechanisms” – the ability to connect a particular object to its background – in the hippocampus. The older people also had diminished object processing in the lateral occipital cortex.

The most striking finding was that the “object areas” of the brains of older East Asian subjects responded much more weakly to novel stimuli than did those same brain regions in the older Americans. For the older East Asians, a lifetime of attention to the backgrounds, or context, of pictures eventually showed up as a diminished response in the part of the brain that keeps track of foreground objects.

One of the best ways of keeping the brain healthy is with cognitive cross training: doing things like crossword puzzles, but also doing things that exercise other cognitive muscles, like playing the piano. This research would suggest that the exact strategies that we should use will be different in native-born Asian and western-born people. Something to factor in the next time that we get some advice about how to keep the brain young for as long as possible.