This story is from the category The Brain
Date posted: 23/08/2012
Ancient Greek philosophers considered the ability to "know thyself" as the pinnacle of humanity. Now, thousands of years later, neuroscientists are trying to decipher precisely how the human brain constructs our sense of self.
Self-awareness is defined as being aware of oneself, including one's traits, feelings, and behaviors. Neuroscientists have believed that three brain regions are critical for self-awareness: the insular cortex, the anterior cingulate cortex, and the medial prefrontal cortex.
However, a research team led by the University of Iowa has challenged this theory by showing that self-awareness is more a product of a diffuse patchwork of pathways in the brain -- including other regions -- rather than confined to specific areas.
The conclusions came from a rare opportunity to study a person with extensive brain damage to the three regions believed critical for self-awareness. The person, a 57-year-old, college-educated man known as "Patient R," passed all standard tests of self-awareness. He also displayed repeated self-recognition, both when looking in the mirror and when identifying himself in unaltered photographs taken during all periods of his life.
"What this research clearly shows is that self-awareness corresponds to a brain process that cannot be localized to a single region of the brain," says David Rudrauf, co-corresponding author of the paper, published online Aug. 22 in the journal PLoS ONE. "In all likelihood, self-awareness emerges from much more distributed interactions among networks of brain regions."
The authors believe the brainstem, thalamus, and posteromedial cortices play roles in self-awareness, as has been theorized.
The researchers observed that Patient R's behaviors and communication often reflected depth and self-insight. First author Carissa Philippi, who earned her doctorate in neuroscience at the UI in 2011, conducted a detailed self-awareness interview with Patient R and found he had a deep capacity for introspection, one of humans' most evolved features of self-awareness.
"During the interview, I asked him how he would describe himself to somebody," says Philippi, now a postdoctoral research scholar at the University of Wisconsin-Madison. "He said, 'I am just a normal person with a bad memory.'"
Patient R also demonstrated self-agency, meaning the ability to perceive that an action is the consequence of one's own intention. When rating himself on personality measures collected over the course of a year, Patient R showed a stable ability to think about and perceive himself. However, his brain damage also affected his temporal lobes, causing severe amnesia that has disrupted his ability to update new memories into his "autobiographical self." Beyond this disruption, all other features of R's self-awareness remained fundamentally intact.
"Most people who meet R for the first time have no idea that anything is wrong with him," notes Rudrauf, a former assistant professor of neurology at the UI and now a research scientist at the INSERM Laboratory of Functional Imaging in France. "They see a normal-looking middle-aged man who walks, talks, listens, and acts no differently than the average person.
"According to previous research, this man should be a zombie," he adds. "But as we have shown, he is certainly not one. Once you've had the chance to meet him, you immediately recognize that he is self-aware."
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