Your brain off the leash

I recently finished Michael Pollan’s new book, How to Change Your Mind (with long subtitle). It’s about the resurgence in studies of psychedelic substances, such as LSD and psilocybin, and how they affect the brain (including his). It’s also about how they might be useful therapeutically.

For me, the most interesting bit was learning about the default mode network—brain structures first described in 2001. I’d never heard of this network (DMN). It links parts of the cerebral cortex with older (evolutionarily speaking) parts of the brain and acts as a sort of orchestra conductor, keeping order in a system that might otherwise “descend into the anarchy of mental illness.” It acts as a kind of filter, admitting only the information required for us to get through the day. Otherwise, the torrent of information coming at our senses at any given moment would be difficult to process. It also plays a role in the creation of various mental constructs, the most important of which is our sense of self (our egos). It’s most active when we are involved in higher-level cognitive processes such as self- reflection, mental time travel, and trying to imagine what it is like to be someone else. By the way, the DMN isn’t operational until late in a child’s development.

When the default mode network goes quiet—the effect of psychedelics—our other centers of mental activity are “let off the leash,” allowing material otherwise unavailable to us to float to the surface. In this state, people feel a loss of ego and that they are a part of nature. Here’s a graphic image comparing the brain activity when the DMN is in charge (left) and when it is not (under the effect of psilocybin).

Kind of exciting, don't you think? (I'll discuss therapeutic uses next week.)

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