blogs

What percentage of your brain do you use?

2022-Nov-23

An enduring myth says we use only 10% of our brain the other 90% standing idly by for spare capacity huckster's promise to unlock that hidden potential with methods based on neuroscience. But all they really unlock is your wallet 2/3 of the public and nearly half of science teachers mistakenly believe the 10% myth. In the 1890s William James the father of American psychology said most of us do not meet our mental potential. James met this as a challenge not an indictment of scant brain usage but the misunderstanding stuck also scientists couldn't figure out for a long time the purpose of our massive frontal lobes or broad areas of a pariah lobe damage didn't cause motor or sensory deficits so authorities concluded. They didn't do anything For decades. These parts were called silent areas their function elusive we've since learned that they underscored executive and integrated ability without which we would hardly be human they're crucial to abstract reasoning planning weighing decisions and flexibly adapting to circumstances the idea that 9/10 of your brain sits idly by in your skull. Look silly when we calculate how the brain uses energy rodent and canine brains consume 5% of total body energy monkey brains use 10% and adult human brain which accounts for only 2% of the body's mass consumes 20% of daily glucose burnt, in children that figure is 50% and an infant's 60% this is far more than expected for their relative brain sizes which scale in proportion to body size human ones weigh 1.5 kg elephant brains 5 kg and whale brains 9 kg yet on a per weight basis humans pack in more neurons than any other species this dense packing is what makes us so smart there is a trade off between body size and the number of neurons a primate including us can sustain
A 25 kg ape has to eat 8 hours a day to uphold a brain with 53 billion neurons the invention of cooking one and a 1/2 million years ago gave us a huge advantage. Cooked food is rendered soft and predigested outside of the body are guts more easily absorbed its energy cooking freeze up time and provides more energy than if we ate food stuffs raw and so we can sustain brains with 86 billion densely packed neurons 40% more than the ape.


Here's how it works half the calories of brain Burns go towards simply keeping the structure intact by pumping sodium and potassium ion across membranes to maintain an electrical charge to do this the brain has to be an energy hawk it consumes an astounding 3.4 × 10 ^ 21 ATP molecules per minute ATP being the coal of the body's furnace the high cost of maintaining resting potentials in all 86 billion neurons means that little energy is left to propel signals down axons and across sign axes the nerve discharges but actually get things done even if only a timed percentage of neurons fired in a given region at any one time the energy burden of generating spikes over the entire brain would be unsustainable.


Here's where energy efficiency comes in letting just a small proportion of cells signal at any 1 time known as sparse coding uses the least energy but carries the most information because the small number of signals have thousands of possible paths by which to distribute themselves a drawback of sparse coating within a huge number of neurons is its cost worse if a big proportion of cells never fire than they are superfluous and evolution should have jettisoned them long ago the solution is to find the optimum proportion of cells that the brain can have active at once for maximum efficiency between 1% and 16% of cells should be active at any given moment this is the energy limit we have to live with in order to be conscious at all the need to conserve resources is the reason most of the brain's operations must happen outside of consciousness. It's why multitasking is a fool's errand we simply lack the energy to do 2 things at once let alone 3 or 5 when we try we do each task less well than if we'd given it our full attention the numbers are against us your brain is already smart and powerful so powerful that it needs a lot of power to stay powerful and so smart that it has Built-in an energy efficiency plan. So don't let a fraudulent myth make you guarantee about your supposedly lazy brain gilt would be a waste of energy after all this don't you realize it's dumb to waste mental energy you have billions of power hungry neurons to maintain so hop to it.