Neuroscientists who study consciousness have suggested that self-awareness depends on the presence of very specific "higher order" regions of the brain. In turn, that means that any serious impairment to these critical areas would virtually eliminate any sense someone has of themselves as a separate person. At least, that's how the theory goes.
But now, a detailed analysis of a patient with a rare neurological condition has cast doubt on this assumption, indicating that self-awareness does not require a complex brain.
When it comes to the brain organs of self-awareness, neuroscientists have isolated the insular cortex, the anterior cingulate cortex (ACC), and the medial prefrontal cortex (mPFC). But in a recent paper published in PLOS, a research team tested this theory by studying a man with extensive bilateral brain damage that affected all three of these regions — and quite severely. After a severe bout of herpes simplex encephalitis (which causes inflammation of the brain), only 10% of the patient's insula remained, along with only 1% of his ACC.
The patient in question is a 57 year-old-man known as "Roger." He suffers from extreme amnesia, a condition that has partially affected his "autobiographical self." At the same time, however, Roger's sense of himself — things like his basic self-recognition and sense of self-agency — have largely remained intact. Clearly, this was a result that the scientists, a team lead by David Rudrauf and Carissa Phillippi, were not expecting.
Writing in Scientific American, Ferris Jabr goes over the details of their experiments:
In a mirror recognition task, for example, a researcher pretended to brush something off of Roger's nose with a tissue that concealed black eye shadow. 15 minutes later, the researcher asked Roger to look at himself in the mirror. Roger immediately rubbed away the black smudge on his nose and wondered aloud how it got there in the first place.
Philippi and Rudrauf also showed Roger photographs of himself, of people he knew and of strangers. He almost always recognized himself and never mistook someone else for himself, but he sometimes had difficulty recognizing a photo of his face when it appeared by itself on a black background, absent of hair and clothing.
Roger also distinguished the sensation of tickling himself from the feeling of someone else tickling him and consistently found the latter more stimulating. When one researcher asked for permission to tickler Roger's armpits, he replied, "Got a towel?" As Philippi and Rudrauf note, Roger's quick wit indicates that in addition to maintaining a sense of self, he adopts the perspective of others-a talent known as theory of mind. He anticipated that the researcher would notice his sweaty armpits and used humor to preempt any awkwardness.
In another task, Roger had to use a computer mouse to drag a blue box from the center of a computer screen towards a green box in one of the corners of the screen. In some cases, the program gave him complete control over the blue box; in other cases, the program restricted his control. Roger easily discriminated between sessions in which he had full control and times when some other force was at work. In other words, he understood when he was and was not responsible for certain actions.
These tests indicated that, even without the complex brain regions that were thought to elicit self-awareness, Roger still has a stable self-concept and intact higher-order metacognitive abilities.
The researchers concluded that the insular cortex, ACC and mPFC are not required for most aspects of self-awareness. Instead, they are now suggesting that self-awareness is likely to emerge from more distributed interactions among brain networks, including those in the brainstem, thalamus, and posteromedial cortices.
The entire study is freely available as PLOS.
Image of Roger's brainscans via University of Iowa. Top image Oliver Sved/Shutterstock.com.