The Neural Basis of the Self

Perhaps the most personal and most quintessentially human aspect of our existence is the experience of our ‘self.’ What contemporary philosopher Daniel Dennett has described as the unitary narration of our experience, the ‘author’ of our life. Artists, writers, philosophers and psychologists dedicate much of their attention to describing and discerning the kernels of the self. And now, cognitive neuroscientists have entered the debate. With the recent advent of brain imaging technologies, researchers now have a tool to take a stab at this fundamental, though esoteric, question.

Based on brain imaging studies, the medial prefrontal cortex (MPFC) seems to play a pivotal role in the self. For example, the MPFC is more active when participants make judgments about themselves, compared to other semantic judgments (i.e. I am a good friend vs. you need water to live). Similarly, MPFC is recruited when subjects retrieve memories about themselves compared to a fictional character. Interestingly, the MPFC is also recruited when participants passively rest while undergoing an fMRI scan. Until recently, most fMRI scans required that participants perform cognitive tasks during scanning, and researchers mapped statistically significant brain activation to cognitive components of the task. However, a recent trend in brain imaging is to identify the neural circuitry active during humans’ resting state, or when they are not performing tasks and instead are free to think about whatever they want. During such scans, a few brain areas are active, including the MPFC. It has been hypothesized that the MPFC activation represents the ongoing self-related processing during a conscious state, orchestrating the ‘authorship’ of our daily experiences.

However, such interpretations are controversial. Most notably, skeptics argue that 2identifying the neuroanatomy during rest does not reveal anything about the cognitive content that corresponds with it. Although previous studies identify the MPFC as crucial in self judgments and reflection, this is not enough evidence to suggest that during our day-to-day experience, it is the hub unifying and personalizing our conscious experience.

Skepticism aside, the findings reflect the reality that cognitive neuroscience is beginning to address questions previously believed to be unanswerable. In his recent book, “Proust was a Neuroscientist,” Jonah Lehrer elegantly draws connections between the philosophies of great artists that now, hundreds of years later, garner empirical support from the neurosciences. Virginia Woolf, one of the profiled artists, attempted to translate the contents of her resting state into written narration. Today, scientists are trying to identify the brain mechanisms underlying this narrative content. As Lehrer argues, it may be that in this pursuit, science could learn from art, and hopefully create studies that better isolate the content of the self and it’s related brain architecture.

References

Gusnard, D. (2001). Medial prefrontal cortex and self-referential mental activity: Relation to a default mode of brain function Proceedings of the National Academy of Sciences, 98 (7), 4259-4264 DOI: 10.1073/pnas.071043098

Kelley, W.M., Macrae, C.N., Wyland, C.L., Caglar, S., Inati, S. & Heatherton, T. F. (2002). Finding the self? An event-related fMRI study. Journal of Cognitive Neuroscience, 14(5), 785-794.

Pfeifer, J., Lieberman, M., & Dapretto, M. (2007). ?I Know You Are But What Am I?!?: Neural Bases of Self- and Social Knowledge Retrieval in Children and Adults Journal of Cognitive Neuroscience, 19 (8), 1323-1337 DOI: 10.1162/jocn.2007.19.8.1323