Do we have brain to spare?

  title={Do we have brain to spare?},
  author={David A. Drachman},
  pages={2004 - 2005}
  • D. Drachman
  • Published 28 June 2005
  • Biology, Psychology
  • Neurology
Within the liter and a half of human brain, stereologic studies estimate that there are approximately 20 billion neocortical neurons, with an average of 7,000 synaptic connections each.1 The cerebral cortex has about 0.15 quadrillion synapses—or about a trillion synapses per cubic centimeter of cortex. The white matter of the brain contains approximately 150,000 to 180,000 km of myelinated nerve fibers at age 20, connecting all these neuronal elements. Despite the monumental number of… 
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