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We came a long way. The question of the self was raised in ancient Greek philosophy and has persisted ever since. Every generation asks questions about the nature of the self. For instance, Descartes argued that the mind is the self and that it is sustained by a specific mental substance that is different from the physical substance of brain and body. Nowadays many argue that there is no such self—there is the brain and nothing else. The self is an illusion, the philosopher Thomas Metzinger claims. Is that true? This is the moment where one wants to revert from philosophical speculation to scientific evidence.
I ventured into different empirical results about the self in my recent blog posts. There was the finding that stimuli like trait adjectives that are strongly related to your own person elicit strong activity in a particular set of regions in the brain, the so-called cortical midline structure. This suggests that our brain and its neural activity are very sensitive to personal relevance or self-relatedness. The self matters for the brain and its neural activity. Empirical evidence thus opts against the irrelevance of the self for the brain’s neural activity. And that in turn makes it rather unlikely that the self is a mere illusion as current philosophers like to postulate. Even if the self is no one for us in our philosophical speculation, it is at least somebody for the brain and its neural activity.
Does this mean that the self is located in a particular brain region or network, like the cortical midline structures? No it only means that these regions’ neural activity is particularly sensitive to self-related stimuli. Other regions and networks may participate too as it has been shown but these are not as sensitive to self-related stimuli in their neural reactivity. Why then is the neural activity in specifically the midline regions so sensitive to the self? We currently do not know. Maybe there are some specific physiological and neuronal properties in these regions that distinguishes them from other regions and makes them suit perfectly for processing what we describe as personal relevance or self-relatedness. This is the subject of intense research in my group.
My last blog described the overlap between resting state or spontaneous activity and self-related activity. Specifically, the study by Bai et al. (2015) could demonstrate that the pre-stimulus resting state activity level predicts whether we perceive and experience a stimulus, e.g., an emotional picture, as high or low-self-related. How is that possible? This is only possible when the brain’s resting state or spontaneous activity contains or better encodes some information about the self, e.g., about what might be personally relevant or self-related to that particular person. This led me to suggest what I described in a recent paper as “rest-self containment” (Northoff 2015), namely that the brain’s resting state or spontaneous activity contains some information about the self, e.g., something that might be personally relevant for the respective owner of the brain.
Such rest-self containment carries major implications. As I outline in the paper (Northoff 2015), we traditionally conceive the self as higher-order cognitive or mental feature that stems from its association with the mind by Descartes. Such self as a higher-order feature of the mind has to be distinguished from lower-order features associated with brain and body. This Cartesian Dualism now resurfaces in the brain in that the self is often associated with higher-order cognitive functions in the prefrontal cortex as distinguished from lower-order sensory function in sensory cortex. The findings speak a different language though. The self is neither associated with higher-order cognitive nor lower-order sensory functions and their respective regions. Instead, the self is already encoded into the brain’s resting state or spontaneous activity. It is thus a basic and most fundamental function of the brain. It is the floor upon which everything else stands rather than tables (the sensory functions) and their beautiful vases (the higher-order cognitive functions). The self is thus a basic and fundamental feature of the brain rather than being a higher-order cognitive feature of the mind. The findings thus tell us that we need to reverse Descartes and put the self from the upper echelons of the mind down to its ground floor in the brain.
How does the self come into the brain’s resting state or spontaneous activity though? You recall my blog about the early childhood trauma that were predicted by the degree of disorganisation or chaos, e.g., entropy, in the adult brain’s spontaneous activity (Duncan et al. 2015). The self may enter the brain’s spontaneous activity by exposure to the world and its relation to the brain. If so, the self may consists in the most concrete, basic and fundamental world-brain relation rather than some lofty and abstract mind that seems to be independent of both world and brain. The self is thus relational signifying the relation between world and brain rather than consisting in either physical or mental properties associated with either mind or brain. This provides a different view of self and brain as I outline in my recent book “Neurophilosophy and the Healthy mind. Learning from the unwell brain” that is about to come out (Norton publisher 2015/2016).
In order to understand the self and its basis we need to understand better the brain’s spontaneous activity and how it impacts our actions, emotions, and thoughts. This will be the subject of the next blog. In the meantime, I wish you a nice pre-Christmas time and a merry Christmas.
References
Northoff, G. (2015). Is the self a higher-order or fundamental function of the brain? The "basis model of self-specificity" and its encoding by the brain's spontaneous activity. Cogn Neurosci.
Duncan NW, Hayes DJ, Wiebking C, Tiret B, Pietruska K, Chen DQ, Rainville P, Marjańska M, Ayad O, Doyon J, Hodaie M, Northoff G. (2015). Negative childhood experiences alter a prefrontal-insular-motor cortical network in healthy adults: A preliminary multimodal rsfMRI-fMRI-MRS-dMRI study. Hum Brain Mapp.
Bai Y, Nakao T, Xu J, Qin P, Chaves P, Heinzel A, Duncan N, Lane T, Yen NS, Tsai SY, Northoff G. (2015). Resting state glutamate predicts elevated pre-stimulus alpha during self-relatedness: A combined EEG-MRS study on "rest-self overlap". Soc Neurosci.
Northoff, G (2016): “Neurophilosophy and the Healthy mind. Learning from the unwell brain”. Norton.
http://books.wwnorton.com/books/Author.aspx?id=429498842
