Suzana Herculano-Houzel (1972-) The Human Advantage (2016)
A New Understanding of How Our Brain Became Remarkable
9. So How Much Does It Cost?
...The average metabolic cost of the human brain fell in between, at 5.44 × 10−9 micromole of glucose per neuron per minute. This translates into 3.3 billion molecules of glucose consumed on average per human neuron per minute, which seems like a startling number. Put into perspective, however, it is actually not much. At the rate of 3.3 billion molecules of glucose per neuron per minute, 1 gram of glucose-one-fourth of a teaspoon-contains enough glucose molecules to feed all 86 billion neurons in the human brain for 12 minutes, and 5 grams or 1¼ teaspoons of glucose, enough molecules to power the entire human brain for one full hour!
...The energy budget available for neurons seems to be just barely enough for the maintenance of healthy brain activity compatible with waking, awareness, and consciousness: neurons are constantly pushing the limit. It is no wonder that the brain is particularly sensitive to restrictions in blood supply that compromise the availability of glucose and oxygen.