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What Happens When the Brain "Farts" and Why Does It Matter?

Riki's picture

“To pay attention, this is our endless and proper work.”

Mary Oliver


The brain is responsible for controlling the whole body, so naturally it consumes a respectable amount of the body’s energy – up to 20 percent. This being the largest energy usage of any organ in the body (4), it makes sense that the brain will take any chance for a break (1). However, the I-function is often not aware of the brain’s rest, or at least doesn’t realize until a mistake has been made. Colloquially, these mistakes are better known as “brain farts”—and are related to a fundamental neural network. Brain farts are under-researched but not inconsequential, because what they say about the default mode network gives rise to a number of other questions about the brain.


You might notice that you have trouble focusing on a task at hand when it’s one that you’ve done many times before, such as washing the dishes, or more frighteningly, when you’re driving. If the brain recognizes a pattern in the activity as one that has happened before, it will begin slowing down the systems it deems unnecessary for the current task (1). One of the systems on this list is the attention network. As your brain shuts down these processing systems, you experience “mind wandering”. While some networks are becoming inactive, others are firing up. Most widely known is the default mode network. Not surprisingly, the brain doesn’t hesitate to return to the default mode network. In fact, the default mode network must be inhibited before the I-function can engage in conscious activity, like changing lanes on the highway or rereading that paragraph you glazed over (1). Even when researchers directed subjects to pay attention to certain tasks, they found that despite their best efforts, subjects spaced out as much as 50 percent of the time they were supposed to be focusing (2). Assuming the subjects didn’t all have ADD, this shows that it can be difficult to consciously control the activation and inhibition of the default mode network.


During mind wandering, you can either be aware or totally unaware it is happening (2). When you are aware that the I-function isn’t completely attentive to what your body and rest of your mind are doing, minor blunders can be made, but you are usually able to catch the mistake before it happens. When you are unaware of your mind wandering, perhaps your I-function is not processing external stimuli at all; perhaps only when some part of the unconscious brain notices something amiss is the I-function alerted to correct the mistake. Brain farts frequently occur in this unaware state.


If a seasoned knitter stumbled into an fMRI machine and began daydreaming while knitting, a neuroscientist examining the image would be able to foresee a brain fart (possibly in the form of a double stitch or a hole in the knitting) as much as 30 seconds in advance, due to its characteristic neural pattern (1). Of course if the neuroscientist watching the imminent disaster warned the knitter as soon as the pattern was detected, the brain fart would not occur because the knitter would inhibit their default mode network and activate their attention network. If, however, the neuroscientist gave no warning and watched the scene unfold, they would notice the default mode network activity decrease following the knitter’s realization of the brain fart. They would notice high levels of attention network activity, especially in the frontal lobes, in addition to limbic-hypothalamic-pituitary-adrenal axis activity as a result of the stress related to making the mistake (1).


The default mode network is assertive and persistent. Why should the brain expend unnecessary energy to pay attention if it doesn’t have to? It is metabolically efficient for the brain to enter the resting state of the default mode network. You often aren’t even aware the network has been activated because the network is so persistent that it diverts resources from the executive functions keeping one focused (3). The default mode network and the attention network are constantly at odds with each other. However, when these two competing networks reach a certain threshold, brain farts are abundant (1). No one knows yet where this threshold lies. If they were to determine it, I doubt it would be the same for everyone. Given the plastic nature of the brain, could one adjust the threshold with some sort of training? If so, this might be a way to keep the mind from wandering when performing repetitive tasks.


My preliminary research on brain farts led to a plethora of interesting studies on the default mode network. I have sorted through some of it and have many lingering thoughts, some of which I might address in my next web paper. If the default mode network is associated with an awake but resting brain state, what role does it play during sleep? “Day dreaming”, the subjective experience of the default mode network, implies some connection to “night” dreaming. During sleep, the brain is not processing as much external stimuli as it does when awake. Similarly, when awake and mind wandering your brain does not process as much external stimuli as it does when it is more attentive. REM activity in the brain resembles an awake state, though obviously you are asleep, so can you become distracted via default mode network activation during a dream?


As stated previously, the attention network and default mode network play an incessant game of tug-of-war. Might the threshold hold a significant position in sources or results of mental disorders? Maybe the networks aren’t competing at all; rather they are working together in a way that doesn’t seem ideal to the I-function’s desire/societal internalization to accomplish many tasks, but is ideal to achieving one’s optimal unconscious state. This idea can be tangled in the web of arguments surrounding free will.


Another subject of interest to be explored is the relationship between the default mode network and various mental disorders. The default mode network is associated with self-referential thinking (2). If this state is the brain’s default, perhaps preferred state, then self-referential thinking must be essential to functioning. Indeed, it seems to be adaptive to reflect on one’s past actions and behaviors and their subsequent consequences to determine a better way to handle future situations. Nevertheless, too much of something beneficial is frequently detrimental. I imagine depression might be a disorder of an overactive default mode network (or, conversely, the latter is merely a symptom of the former). Depressives are drowning in an indomitable quagmire of self-referential thinking. This means they must have extraordinary difficulty inhibiting the default mode network. Again, if they were to somehow manipulate the threshold, could their depression be lifted to some extent? Do anti-depressants affect the default mode network directly? If depressives are experiencing too much self-referential thinking, can this thinking become exaggerated and distorted, or is it merely the “self” that becomes distorted? ADD and ADHD seem obviously tied to the default mode network. Perhaps they too have trouble inhibiting the network. But ADD/ADHD and depression are not always comorbid disorders, which suggests that an overactive default mode network is just a symptom of both disorders and not a cause. I’m curious to know the bond between the default mode network and other mental disorders.


Throughout this paper, I have assumed the I-function is not related to the default mode network because often one is not aware of the default mode network’s activation, and the I-function is conscious perception and the “self”, but self-referential thinking is about the consciously perceived “self”, so how could the default mode network not be related to the I-function? Then, do self-aware animals have default mode networks? If an animal is not self-aware, does that mean it does not have a default mode network? What mechanism works in its place to conserve the brain’s energy?


Brain farts, though not heavily researched, are a small piece of the puzzle that is the default mode network. This network is currently an area of great interest to neuroscientists, and I hope to uncover more questions and answers surrounding this network in my next web paper.




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Paul Grobstein's picture

"attention" and "default" networks

Very interesting set of issues.  One might indeed argue that its not "attention" vs "no attention" but rather a matter of what one is paying attention to, things outside or things inside.  And it is indeed interesting to think of these set of issues in connection with the "rumination" often associated with depression.   Is that inherent in depression or something that results from an I-function that is not entirely comfortable in the default network state?