What is the neural correlate of the self? The easy answer is that nobody knows. We have yet to discover a neurological patient who has lost their sense of identity, but still retained their conscious sensations. Nevertheless, certain brain areas have been implicated in distinguishing the self from non-self.
This 2006 paper by Todd Heatherton of Dartmouth, for example, detected increased activity in the medial prefrontal cortex (mPFC) when people were forced to perform “self-referrent tasks”. In other words, the mPFC is what recognizes your reflection in the mirror. It might not be the source of our identity – the self probably isn’t reducible into any single brain region – but it is certainly part of the self-awareness network.
In a fascinating paper in the new Neuroimage, scientists in China explore the cultural implications of this research. As they observe in their paper, our sense of self is subject to a wide variety of cultural influences:
Social psychologists have found that Westerners (North Americans and Europeans) tend to view the self as an autonomous entity separating from others and to behave according to their own internal attributes and thoughts (the independent self). In contrast, East Asians emphasize the interconnectedness of human beings along with contingencies between the individual’s behavior and the thoughts and actions of others in the relationship (the interdependent self). However, it remains unknown how the cultural influence on self-representation is accomplished in the human brain.
To test this sociological truism, the Chinese neuroscientists imaged people of “Western” and “Eastern” heritage. As Heatherton had found a year before, Westerners used the mPFC to distinguish between themselves and others. On the other hand, the activity of the mPFC of Chinese subjects did not correlate with the representation of the self. Instead, it was activated both by images of themselves and by images of loved ones, like their mother. Their self was literally “interdependent”.
The authors conclude that culture has profound effects on even the most basic elements of brain processing:
These fMRI results showed strong empirical evidence that MPFC mediates cultural influence on the neural substrates of representation of self and close others. While social psychological studies suggest that cultures create habitual ways of processing information related to the self and one’s important others, our fMRI results indicate that these habitual cognitive processes are accompanied by detectible parallel neural processes. The relatively heavy emphasis on interpersonal connectedness in Chinese culture has led to the development of neural unification of the self and intimate persons such as mother, whereas the relative dominance of an independent self in Western cultures results in neural separation between the self and others (emphasis mine).
Hat Tip: Neuroeconomics blog