Hello,
So my question is, our body uses a certain amount of energy through the day and 20% of that is used exclusively by the brain.
Why can’t we increase or decrease the calorie usage of our minds to burn more or less calories?
My own theory is that the brain runs on a base threshold of energy and it normally is around 20% but it doesn’t explain why doing brain teasers/puzzles doesn’t increase it.
And bonus if you can explain how doing extremely challenging problems for any amount of time makes you feel physically tired (such as taking a test).
Edit: there have been a amazing amount of answers while I was asleep (posted this before sleeping for a solid 10 hours), my questions about the brain functionality has been answered
In: 7004
Apologies to any neuroscientists who happen to read this and start foaming at the mouth from my mischaracterization-through-simplification explanations. I can’t quite ELI*5*, but this is the best *ELI’mNotAGradStudentInBiology* I can come up with.
A few points I didn’t see discussed elsewhere:
You only have conscious access to a tiny fraction of your brain. Almost all brain activity, including most “thinking” is done by structures that are opaque to the conscious mind. For example, both your eyes have a large blind spot where the optic nerve attaches to the retina, but the image “you” consciously see has that gap already filled in by some tiny corner of your brain you probably don’t even know exists. That function burns a (probably pretty steady) number of calories and absolutely no amount of conscious exercise of will is going to result in you being able to “turn that off” and see the image that actually registers in your eyes. So not only are the parts of your brain associated with non-conscious activities (breathing, heartbeat, endocrine system, etc.) unable to be controlled or even really affected by your conscious choices, but many parts of your brain associated with things you consciously do (looking, reading, listening, speaking, etc.) are done outside of conscious control. And that god they are! Can you imagine what a nightmare even just talking would be if you had to consciously control your lungs, vocal cords, tongue, etc. not to mention all of the rules of grammar and pronunciation for every single word?
Many people think the brain is like a computer, and they know that power consumption on a computer goes way up the “harder” it works on something. But that wasn’t always the case; back in the day DOS and even early Windows machines drew a steady amount of power no matter what you were doing. If, for example, running full-bore 100% processor utilization programs like something that calculates a million digits of pi took 100W of power for the processor, then just sitting there blinking the cursor would take the same 100W. This is actually a problem you can run into when using virtual machines of old operating systems that are expecting old chips like 8088 and 8086/286.
As to your “bonus,” nobody is certain exactly how mental effort leads to physical exhaustion, but it is generally believed that by burning large amounts of glucose (the simple carbohydrate that your body, especially the brain, uses for power) your brain will make more adenosine. Adenosine (in its triphosphate form, ATP) is a compound that your brain uses during the physical act of thinking, it’s like the raw material that drives the actual electrical impulses that constitute thought. It also blocks the absorption of (or maybe the production of?) dopamine, the hormone that helps you concentrate and, in general, exercise conscious will. With your dopamine depressed literally everything seems to take more and more effort, which your conscious mind interprets as “being tired.” It’s the same reason people with depression disorders lay around and sleep a lot. Assuming you’re normal/healthy, your brain is able to get more glucose fairly quickly, but the “lack of available energy” isn’t what is actually causing the fatigue, your brain’s perception of it performance is.
Latest Answers