The entire brain weighs three pounds (1.4 kg) and so is only a small percentage of an adult’s total body weight, typically 2%. But it consumes 20% of all the energy the body uses. Why? The perhaps oversimplified answer is that time is energy.
Neural communication is very rapid — it has to be — reaching speeds of over 300 miles per hour and with neurons communicating with one another hundreds of times per second. The voltage output of a single resting neuron is 70 millivolts, about the same as the line output of an iPod. If you could hook up a neuron to a pair of earbuds, you could actually hear its rhythmic output as a series of clicks.
[…]
Neurochemicals that control communication between neurons are manufactured in the brain itself. These include some relatively well-known ones such as serotonin, dopamine, oxytocin, and epinephrine, as well as acetylcholine, GABA, glutamate, and endocannabinoids. Chemicals are released in very specific locations and they act on specific synapses to change the flow of information in the brain. Manufacturing these chemicals, and dispersing them to regulate and modulate brain activity, requires energy — neurons are living cells with a metabolism, and they get that energy from glucose. No other tissue in the body relies solely on glucose for energy except the testes. (This is why men occasionally experience a battle for resources between their brains and their glands.)
Daniel J. Levitin, The Organized Mind, 2014.
October 16, 2015
QotD: This explains so much
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