“It is estimated that we have over 100 billion neurons (also called nerve cells or brain cells), which is

about the number of stars in the Milky Way Galaxy. Here are also trillions of supportive cells in the brain called glia. Each neuron is connected to other neurons by up to 40,000 individual connections (called synapses) between cells. Multiplying 100 billion neurons times 40,000 synapses is equivalent to
the brain having more connections in it than there are stars in the universe. A piece of brain tissue the size of a grain of sand contains 100,000 neurons and 1 billion synapses, all "talking" to one another.” - Daniel Amen