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. Author manuscript; available in PMC: 2015 Jan 22.
Published in final edited form as: Neuron. 2014 Jan 22;81(2):224–226. doi: 10.1016/j.neuron.2014.01.006
  • 01

    Weight: ~1,375 grams in male, ~1,275 grams in females

  • 02

    Number of neurons: ~86,000,000,000

  • 03

    Number of synapses: ~100,000,000,000,000

  • 04

    Number of neocortical neurons: >20,000,000,000

  • 05

    Number of neocortical glial cells: >35,000,000,000

  • 06

    Asymmetry: left side has 186,000,000 more neurons

  • 07

    Total length of myelinated fibers: ~100,000 miles

  • 08

    Total length of blood vessels: ~100,000 miles

  • 09

    Number of fibers in corpus callosum: ~250,000,000

  • 10

    Body’s energy usage: 20%

  • 11

    Energy generation: 10–23 watts (could power a light bulb)

  • 12

    Oxygen consumption: 94% gray matter, 6% white matter

  • 13

    Organic composition: 60% fat

  • 14

    Maximum transmission speed : >250 mph

  • 15

    Membrane surface area of neurons: 25,000 m2

  • 16

    Birth of neurons during peak of neurogenesis: 250,000/minute

  • 17

    Average loss of neocortical neurons: ~85,000/day

  • 18

    Sensory system input: 11 million bits/second

  • 19

    Conscious awareness of sensory input: less than 50 bits/second

  • 20

    Number of thoughts: 70,000/day