The Oscillation of Attention
I found a number of fascinating ideas in Michael Pollan’s book, How to Change Your Mind. I am going to simply list a number of quotes from the chapter on “The Neuroscience” then add some thoughts around them.
“[Marcus] Raichle had noticed that several areas in the brain exhibited heightened activity precisely when his subjects were doing nothing mentally. This was the brain’s “default mode,” the network of brain structures that light up with activity when there are no demands on our attention and we have no mental task to perform. Put another way, Raichle had discovered the place where our minds go to wander – to daydream, ruminate, travel in time, reflect on ourselves, and worry. It may be through these very structures that the stream of our consciousness flows.
The default network stands in a kind of seesaw relationship with the attentional networks that wake up whenever the outside world demands our attention; when one is active, the other goes quiet, and vice versa.”
“…working at a remove from our sensory processing of the outside world, the default mode is most active when we are engaged in higher-level “metacognitive” processes, such as self-reflection, mental time travel, mental constructions (such as the self or ego), moral reasoning, and “theory of mind” – the ability to attribute mental states to others, as when we try to imagine “what it is like” to be someone else.”
“ ‘The brain is a hierarchical system’ [Robin] Carhart-Harris explained in one of our interviews. ‘The highest-level parts’ – those developed late in our evolution, typically located in the cortex – ‘exert an inhibitory influence on the lower-level [and older] parts, like emotion and memory.’ ”
“…the default mode network appears to play a role in the creation of mental constructs or projections, the most important of which is the construct we call the self, or ego….Nodes in the default network are thought to be responsible for autobiographical memory, the material from which we compose the story of who we are, by linking our past experiences with what happens to us and with projections of our future goals.”
“Taken as a whole, the default mode network exerts in inhibitory influence on other parts of the brain, notably including the limbic regions involved in emotion and memory, in much the same way Freud conceived of the ego keeping the anarchic forces of the unconscious id in check.”
It appears to me that what is being offered in these quotes is that the inhibitory nature of the default mode network (DMN) both suppresses the immediate appetites of the Id, and allows us to distinguish a “self” out of all the incoming data streaming from our immediate sensings. When the outside world does not demand our attention, our attention goes to “…composing the story of who we are…”
In talking about the DMN, Pollan also adds “If not for the brain’s filtering mechanisms, the torrent of information the senses make available to our brains at any given moment might prove difficult to process – as indeed is sometimes the case during the psychedelic experience.” I can attest to this torrent from my own experiences with hallucinogens when I was young. The rate at which that torrent flowed was often much too fast for any assessment, descriptions or meaning-making to occur, which would, on occasion, be unsettling. The suppression of that torrent is apparently how the ego arose and so it seems to be fundamental to self-reflective awareness. Remember that this suppression comes from ‘The highest-level parts’ [of the brain] – those developed late in our evolution, typically located in the cortex”, which makes sense.
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