Most neuroscientists would agree that the human brain has adapted over time to meet the challenges of life. One of the biggest challenges to adaptation for the self, the sense of one’s unique existence, is other people.
One’s sense of self is used in numerous social areas such as fantasizing, distinguishing oneself as separate from others, and in developing one’s identity and is a crucial aspect of social functioning. At the APS Annual Convention in Atlanta, Todd Heatherton, Dartmouth College, examined how the brain processes are related to the sense of self during an invited address, “A Social Brain Sciences Approach to Understanding the Self.”
According to Heatherton, several methods can be used to study the social brain, including cognitive tasks, studying patients with certain disorders or brain damage, and neuroimaging. In a series of five studies, Heatherton used fMRI techniques and a split-brain patient in an attempt to learn more about the sense of self. Studies using fMRI are well suited, Heatherton said, because they help distinguish relevant brain functions that are important in the sense of self. Although fMRI studies will not reveal an exact location for the self in brain, Heatherton suggests, it will “allow us to find a set of processes that contribute to the sense of self that we have, like consciousness, memory, and emotion.”
Heatherton has used a self-referent task to investigate how people perform tasks that are self-relevant (i.e., related to the self) and other-relevant (i.e., related to someone else). Some of these tasks involve a subsequent memory test. Previous research has shown that people tend to remember items that are processed with reference to the self better than those that are processed with reference to others. Heatherton states that two reasons are usually given for this effect. The first suggests that there is something unique about the self, which causes people to remember self-referent items better. The other reason suggests that items related to the self are remembered better because they are processed at a deeper level. However, both propositions make the same prediction – items related to the self are remembered better. Standard behavioral measures cannot support one proposition over the other. Heatherton believes that fMRI studies can provide good evidence in support of which proposition is more accurate. He contends that if a level of processing proposition is correct, the brain’s left inferior frontal cortex should be active during a self-referent task as compared to an other-referent task. However, if there is something special about the self, other areas of the prefrontal cortex should be active during self-referent tasks as compared to other referent tasks.
Heatherton’s studies support the proposition that there is something special about the self as opposed to the idea that self-referent tasks lead to a deeper level of processing. His fMRI studies revealed that during self-referent and other-referent tasks, the left inferior frontal cortex is equally active. During a self-referent task, however, the medial prefrontal cortex is active while during an other-referent task it is deactivated. This pattern of activation and deactivation occurs during the self and other referent tasks, and during the memory test of the self and other referent items. In addition, Heatherton’s research reveals that this pattern of activation and deactivation of the left medial prefrontal cortex is replicable when different types of self and other referent tasks are used. The medial prefrontal cortex is an important area when considering the sense of self.
“The medial prefrontal regions are recruited during self-referential processing and that activity in this medial prefrontal area predicts subsequent memory for information processed with relevance to the self,” Heatherton said.
According to Heatherton, knowledge about the self is represented in the brain in the medial prefrontal cortex, but he has not found the region of the brain where the self is located. He contends that the medial prefrontal cortex is involved in other areas of social processes such as memory, affect, and social decisions that give rise to the sense of self.
“Instead of saying that imaging is just phrenology brain mapping, rather it is allowing us to identify the important brain regions that might be vital to being able to do things like processing information about you and about others,” Heatherton said.