“It is much easier to feel the self than to define the self.” (Gordon Allport, 1961)
Philosophers have written a great deal about consciousness and the self. In contrast, many have doubted that these concepts belong in the realm of the neurosciences. I disagree. We should neither let centuries of philosophical debate stand in our way nor intimidate us. I agree with the philosopher John Searle who said that studying the brain without studying consciousness was like studying the stomach without studying digestion! I am therefore happy to report that studies of the self, self-awareness and consciousness have now become quite common in the neuroscientific literature.
A historical parallel
In the early days of neuropsychology, in the 19th century, people´s understanding of language was very limited. This did not prevent clinicians and researchers from studying patients with brain damage and language difficulties (aphasia). Sweeping claims were made on the basis of limited data and unsophisticated definitions and measurements. Soon after the first reports of cases of aphasia the first anatomical and psychological model of language was developed. We certainly have made progress in understanding language since this time but the old studies are classic and are still read and referred to by every student of neuropsychology and related fields.
Patients with a broken self
So who are the patients we can study to learn about the self? The self is complex and composed of many processes. It is not to be found in one particular place in the brain and there are many ways in which it can be disrupted. We have, for example, a physical self and an autobiographical self (our personal memories). These and other aspects of the self can be disrupted by brain injury or disease.
Anorexic patients can be said to have a disruption in their physical self. They see themselves as fat when in fact they are extremely thin. Those who seek to have their leg amputated because they feel it does not belong to them (see here) also have a disrupted physical self. Those who lose their empathy, i.e. their ability to feel for others, because of a brain injury have lost an important aspect of their social self. There are patients who have no insight into their cognitive, or physical disability. This is called anosognosia and is also a disorder of self-awareness.
Studying the self with brain imaging
Studying patients (the lesion method) is not the only way to study the self. We have other methods available. We now have access to technology that allows us to study self-referential processes in the brain of healthy individuals. I am referring to PET and fMRI. Both the lesion method and PET/fMRI are currently being used in the neuroscientific study of the self.
Northoff and colleagues summarized 27 PET and fMRI studies on self-referential processing in the brain. Their conclusion was that the self-referential processes, which they consider to be at the core of our self, are mediated by cortical midline structures in the brain (most of the areas marked by 1 in the picture below). But many other areas of the brain have also been implicated in the self. What would happen to the self if all these areas got wiped out?
In a new study Philippi and his colleagues studied patient R. who suffered a serious brain injury following encephalitis. His injury covered very many of the brain areas previously shown to be related to self-awareness. In spite of this R´s self-awareness, which was tested in various ways, turned out to be suprisingly intact. We obviously still have a long way to go in understanding how the various parts of the self relate to different brain networks or brain areas. Many years of exciting work lie ahead!
To be continued! My next post will be on mirror neurons and the self.
Northoff, G., Heinzel, A., de Greek, M., Bermpohl, F., Dobrowolny, H. and Panksepp, J. (2006). Self-referential processing in our brain – A meta-analysis of imaging studies on the self. NeuroImage, 31, 440-457.
Phillippi, C.L., Feinstein, J.S., Khalsa, S.S., Damasio, A.,Tranel, D., Landini, G., Williford, K. and Rudrauf, D. (2012). Preserved self-awareness following extensive bilateral brain damage to the insula, anterior cingulate, and medial prefrontal cortices. PLoSONE, 7(8): e38413.
Illustration credit: 1) http://commons.wikimedia.org/wiki/File:Vincent_Bethell_Self_Aware_Placard.png and 2) http://commons.wikimedia.org/wiki/Image:Human_brain_midsagittal_cut_.JPG