Science

TWO MIND-BOGGLING NETWORKS: DEFAULT MODE AND TASK POSITIVE

 

THE FOLLOWING is drawn from the second book in The Bipolar Expert Series, IN SEARCH OF OUR IDENTITY ...

Exciting new brain research is giving us new insights into deep trance states and creativity. Intriguingly, the circuitry involved may also loom large in depression and schizophrenia. This involves the brain’s default mode network (DMN).

The DMN refers to discrete but linked cortical regions that are most active when we are experiencing wakeful rest. When engaged in performing a task, though, a different network becomes dominant, the task positive network (TPN). Believe it or not, until the publication of a 2001 study by Marcus Raischle of Washington University (St Louis), hardly anyone even suspected the brain was organized this way.

In the past, if you were investigating the neural basis to any particular human behavior, standard operating procedure was to perform a scan while engaging the subject in some sort of cognitive task (such as trying to decipher a simple visual puzzle), then seeing which circuits lit up. When Dr Raischle noted that certain areas of the brain seemed to come on line as his subjects were resting between tasks, he decided to take a closer look.

According to Dr Raischle: “It hadn’t occurred to anyone that the brain is actually just as busy when we relax as when we focus on difficult tasks.”

Observing the brain at rest led to the discovery of the DMN, but it took several years before it became a hot research field. Wikipedia states that prior to 2007, there were but 12 published papers that mentioned the DMN. Between 2007 and 2014, we had nearly 1,400. A quick PubMed search reveals that the first DMN study involving bipolar was only published in 2010.

With a field of inquiry this new, we need to acknowledge that a good many study findings will be tentative, at best, no matter how rigorously researched, and that any attempts to generalize necessarily involves a good deal of speculation. Nevertheless, a picture is emerging of a dynamic and fluid brain network that seems to shift in and out of various states according to the laws of quantum physics.

We start with the proposition that this network is most active during our resting state. But here’s the catch. The circuitry is far more dense than those parts of the brain we associate with performing tasks and is metabolically far more active. This means a lot more is going on than simply the brain idling in neutral. As more studies get published, we are discovering that the DMN is associated with our own internal dialogues, that these dialogues are vital to our sense of self, and that without this sense of self, the tasks we perform have no reference point.

It goes deeper than that. It seems that our ability to time travel—to learn from the past and imagine the future, to just plain imagine—zips and zooms along these circuits. Thus, instead of blindly reacting to our immediate environment, we are more cogently responding through our accumulated wisdom and experience. Likewise, we can employ our powers of imagination to anticipate our future and plan ahead.

Not only that, our “theory of mind” appears to derive from the DMN. This refers to our ability to employ our higher sense of self-awareness as a tool in recognizing the mental states of others.

Thus, if we are ever to identify a seat of conscious, it is most likely to be found in the constantly shifting neural connections within the DMN. Significantly, the regions of the brain fingered in Alzheimers correspond to deficits in the regions in the DMN. In this regard, we may think of Alzheimers as not only a loss of memory, but a loss of identity.

We are also discovering the DMN is heavily implicated in depression. This has to do with the proposition that our own internal dialogues may give rise to unhealthy ruminating, self-criticism, and incessant worries over the past and future.

When those around us tell us to “snap out of it,” well now we have a brain science explanation for what they would like to see happen. In effect, they want us to flip our switch from the DMN to the TPN, from the internal morass we are mired in to active engagement in our external world. This, of course, is easier said than done, which strongly implies the need for research into treatments and therapies that would facilitate making the switch.

Coincidentally, new studies into psychedelic drugs are yielding invaluable insights into where to look. Compounds such as LSD first came to the attention of clinicians and researchers in the 1950s as a possible means to help patients see beyond the constraints of their narrow ego identities. With the hippie drug culture of the sixties, however, came the inevitable political reaction. The net effect was a virtual shutdown of research for the next four decades.

Now, we are beginning to see a reboot in the research. One drug of interest includes psilocybin, which occurs naturally from “magic” mushrooms and which enhances serotonin transmission. One effect of the drug is that both the DMN and TPN get turned down. This represents a stark contrast to business as usual, where one mode is expected to phase in while the other phases out. Intriguingly, the very opposite happened when researchers scanned the brains of Tibetan Buddhist monks as they meditated. In this case, the DMN and TPN simultaneously got turned up.

 

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Not surprisingly, when something as out of the ordinary as this happens, the brain is going to have a different experience with reality. Those who have used psilocybin or engaged in deep meditation or, for that matter, simply been struck out of the blue by a sudden shift in awareness, talk about arriving at inner knowing, experiencing a disintegration of the ego, and achieving a profound sense of connection.

According to William James in his classic The Varieties of Religious Experience: “In mystic states we both become one with the Absolute and we become aware of our oneness.”

The experience is typically short, no longer than about 30 minutes, but the effect may stay with the person the rest of his or her life. Indeed, the event is likely to be recalled decades later as life-changing.

Could our altered states provide insights into the hidden forces that influence our our more mundane behavior? According to Robin Cathart-Harris of Imperial College, who has been using psylocibin to investigate the DMN, in the past our only windows into the unconscious have been via dreams and psychotic states. The use of psychedelics in research, he claims, may shed light on that which is latent in the mind.

Now Dr Cathart-Harris and his colleagues feel reasonably confident in proposing “the entropic brain hypothesis,” which imagines our consciousness along a broad spectrum ranging from high disorder flexible states (think of something fluid) to low disorder rigid states (think of something solid), with our normal waking conscious in the middle.

Is there a place in this spectrum for realities existing beyond our normal conscious . In this regard, one can be forgiven for simply wanting to turn down the volume. Heaven knows, last thing I need is vivid earthquake dreams, especially living in California.states? Jung certainly thought this was worth looking into when he induced his own meditative trances. His Red Book offers clear physical evidence of what we can achieve when we leave ourselves open to whatever our own inner awareness may reveal.

But we also need to be mindful of the fact that many of us already seem to live inside a much wider mental and sensory and emotional bandwidth than what may be good for us.

In the realm of the psychic and spiritual, psychosis is always lurking in the background, ready at the slightest opportunity of bursting into the foreground. We may indeed have rare gifts. But we need to be careful. Being reduced to a life of eating out of dumpsters should not be the price we pay for acquiring a deeper awareness.

See also Brain Networks and Mental Illness.

Jan 3, 2017

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