You may be the laziest person on the planet, but your brain never rests. So what happens when you’re more or less written off?
In the 1930s, Hans Berger, a German psychiatrist who had recently invented electroencephalogram (EEG), suggest that our brains are always active, even when we don’t seem to be doing much with them. Few people took the idea seriously at the time (perhaps because Berger spent much of his career trying to prove telepathy, or perhaps because he was simply ahead of his time). About 40 years later, in the 1970s, researchers confirmed that blood flow to the brain, a useful proxy for brain activity, varies depending on what you’re doing.
Modern brain imaging
However, it was difficult to learn much about which regions of the brain were active during different activities until the advent of modern brain imaging technology such as positron emission tomography (PET) scans and magnetic resonance (NMR). However, at the turn of the century, scientists used these technologies to study the brain.
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The researchers noticed that when the test subjects were resting in the scanner without performing any particular task (perhaps they were in the control group or simply waiting for the experiment to begin), their brains showed interesting patterns of activity. The researchers found that certain areas of the brain show lower levels of activity when we’re paying attention to a task, but spring into action when we’re not engaged in any particular mental task. Berger was right that the brain is always active; in fact, it turns out that he is very active indeed, even during those periods when he was previously thought to be resting.
Default mode Network
In 2001, a team led by Marcus Reichelneuroscientist at the University of Washington, published first of a series of papers describing the phenomenon and naming this network of brain regions: the Default Network (DMN).
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The brain regions involved in the DMN appear to be primarily: the medial prefrontal cortex, the posterior cingulate cortex, part of the inferior parietal lobe, and sometimes, perhaps, the middle temporal lobe. Perhaps? Yes, the scientists are I’m still working to determine which parts of the brain are involved in the DMN. In fact, there may be several DMNs and different combinations of domains that network for different purposes.
DMN of the brain
One thing that all of these brain areas have in common is that they play a role in the inner voice. The brain’s DMN is activated when we dream, remember, or think about, say, that text your sister sent this morning, what you had for dinner, noticing that the room is getting a little hot, wondering what your cat is thinking when they looking like that, wondering what your sister meant by that text she sent this morning—you know, all those seemingly random thoughts that run through your mind when you’re not focused on anything else. Meanwhile, areas of the brain responsible for things like attention, working memory, and decision-making take a breather.
Why the DMN is important
Since the DMN was discovered, scientists have been working to better understand what it is, what it does, and why it’s important. Although it is early days to understand or even fully define the DMN, the concept has already spawned some fascinating research. some are focused on the role that the DMN—and changes in its patterns—play in dementia. others research looks at the DMN in autism and some types of psychosis. Some researchers are investigating how addiction alters the DMN. The the role of the DMN in post-traumatic stress disorder (PTSD) is another area of research.
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Maybe one of the most interesting ideas about the DMN is that it plays a role in building the self. Brain regions involved in autobiographical memory and self-concepts are part of the DMN. Many of the ideas that float through the mind during this “downtime” are related to our personal lives and our sense of who we are.
So it’s possible that when your brain isn’t doing anything that seems important, it’s actually pretty busy making all the connections that make you feel like you.
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