Biology
How many neurons does the human brain have?
~86 billion neurons
How many neurons does the human brain have?
The human brain contains approximately 86 billion neurons, each forming thousands of synaptic connections. Total synapses: ~100–500 trillion. The number of possible brain states exceeds the number of atoms in the observable universe — which is why no two brains are identical.
Source: Azevedo et al. (2009), Journal of Comparative Neurology