There are 100 billion neurons in the adult human brain, and each neuron makes something like 1,000 to 10,000 contacts with other neurons in the brain. Based on this, people have calculated that the number of permutations and combinations of brain activity exceeds the number of elementary particles in the universe.
Vilayanur S. RamachandranOne of the first things we teach medical students is to listen to the patient by taking a careful medical history. Ninety percent of the time, you can arrive at an uncannily accurate diagnosis by paying close attention, using physical examination and sophisticated lab test to confirm your hunch (and to increase the bill to the insurance company).
Vilayanur S. Ramachandran