Psychedelic mushrooms desynchronize parts of the brain, especially the default mode network, disrupting our normal sense of reality.
Default mode network- sounds rather dull, doesn't it? But somewhere within that pattern of brain activity lies at least some of our consciousness. It is the hum of the brain while we are resting without focus. When we are intensely focused on something outside, in contrast, it is turned down, as we "lose ourselves" in the flow of other activities. This network remains active during light sleep and has altered patterns during REM sleep and dreaming, as one might expect. A recent paper tracked its behavior during exposure to the psychedelic drug psilocybin.
These researchers measured the level of active connectivity between brain regions (by functional MRI) on human subjects given a high dose of psilocybin, or Ritalin- which stands in as another psychoactive stimulant- or nothing. Compared with the control of no treatment, Ritalin caused a slight loss of connectivity (or desynchronization), (below, b), while psilocybin (a) caused huge loss of connectivity, clearly correlated with the subjective intensity of the trip. They also found that if, while on psilocybin, they gave their subjects some task to focus on, their connectivity increased again, again tracking directly with the subjective experiences of their subjects.
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| The researchers show a metric of connectivity between distinct brain regions, under three conditions. FC stands for functional connectivity, where high numbers (and brighter colors) stand for more distance, i.e. less connectivity/synchrony. Methylphenidate is Ritalin. Synchrony is heavily degraded under psilocybin. |
Of all the networks they analyzed, the default mode network (DNM) was most affected. This network runs between the prefrontal cortex, the posterior cingulate cortex, the hippocampus, the angular gyrus, and temporoparietal junction, among others. These are key areas for awareness, memory, time, social relations, and much else that is highly relevant to conscious awareness and personhood. There is a long thread of work in the same vein that shows that psychedelic drugs have these highly correlated effects on subjective experience and brain patterns. A recent review suggested that while subnetworks like the DNM are weakened, the brain as a whole experiences higher synchrony as well as higher receptivity to outside influence in an edgy process that increases its level of (to put it in terms of complexity theory) chaos or criticality.
So that is what is happening! But that is not all. The effects of pychedelics, even from one dose, can be long-lasting, even life-changing. The current researchers note that the DMN desynchronization they see persists, at weaker levels, for weeks. This correlates with the subjective experience of changed senses that can result from a significant drug trip. And that trip, as noted above regarding receptivity and chaos, is a delicate thing, highly subject to the environment and mood the subject is experiencing at the time.
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| But when a task is being done, the subjects come back down towards normalcy. |
These researchers note that brain plasticity comes into play, evidently as a homeostatic response to the wildly novel patterns of brain activation that took the subject out of their rut of DMN self-hood. Synapses change, genes are activated, and the brain reshapes usually in a way that increases receptivity to novel experiences and lifts mood. For example, depression correlates with strong DMN coherence, while successful treatment correlates with less connectivity.
"We propose that psychedelics induce a mode of brain function that is more dynamically flexible, diverse, integrated, and tuned for information sharing, consistent with greater criticality."
So, consider the mind blown. Psychedelics appear to disrupt the usual day-to-day, which is apparently a strongly positive thing to do, both subjectively and clinically. That raises the question of why. Why do we settle into such durable and often negative images of the self and ways of thinking? And why does shaking things up have such positive effects? Jung had a deep conviction that our brains are healing machines, with deep wisdom and powers that are exposed during unusual events, like intense dreams. While there are bad trips, and people who go over the edge from excessive psychedelic use, with a modicum of care, it appears that positive trips, taken in a mood of physical and social safety, let the mind reset in important ways, back to its natural open-ness.
