The brain contains some 100 billion neurons, each of which is linked to tens of thousands of other neurons through a vast network of synapses.
A fleck of brain tissue roughly the size of a match head sports about a billion connections, according to neurobiologist and Nobel Prize–winner Gerald Edelman.
He estimates that the number of possible connections in the typical human brain totals somewhere in the region of ten followed by millions of zeroes, a number far in excess of the number of particles in the known universe.
Astronomical number of associations in brain is responsible for consciousness and thinking