Spying on the sense of self
Sun, 8th Mar 2009
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from the show Your Questions and Swallowing Swords
One of the most intriguing areas of neuroscience at the moment is the issue of the “sense of self” – basically, how we are aware of our own thoughts and personality. Previous research has shown that a few areas of the brain – the prefrontal cortex, the posterior cingulated cortex, and the parietal regions – are involved in self-reflection, and processing our sense of self.
But can we draw a distinction between regions of the brain that are specifically involved in processing thoughts about our “self” from those that are involved in processing thoughts about people in general? New results from researchers in the Netherlands using functional MRI scanning have provided a clue – our sense of self may reside (at least partly) in a region called the anterior insula, deep in the forebrain, which is part of the brain linked to feelings and emotions.
The researchers used sixteen young male volunteers an put them in a functional MRI scanner, which looks at the activity levels of different regions of the brain. They were shown three different types of statements, and were asked to say whether they were true about them, like “I am a good friend”, about someone they knew like a team-mate or classmate, like “So-and-so talks too much”, or just a general knowledge fact like “a vertebra is a bone”.
While asking the volunteers to carry out the task, the researchers monitored their brain activity. They found that when the volunteers were considering the statements about themselves, there was activity in the anterior insula, but this wasn’t seen so much when they were thinking about the general knowledge statements. And, crucially, activity in the anterior insula wasn’t seen when they were thinking about other people.
The team found activity in regions such as the medial prefrontal cortex and the posterior insula when the volunteers were thinking either about themselves or about another person. But the scientists only saw extra activity in the anterior insula when the volunteers thought about statements related to themselves.
These kind of studies are important, not only for scientific interest, but for psychiatrists. There are several illnesses in which a person’s sense of self is disturbed, including schizophrenia. Understanding more about the parts of the brain that are involved could shed light on the roots of these complex diseases, if neuroscientists focus more on them.