The genome combined with experiences make a person who they are. 80 billion neurons connect to 1,000 to 10,000 synapses, and all of those minuscule connections form a person.

1 quadrillion neurons and synapses are in a constant state of flux, meaning a person is consistently changing. All of these connections form the connectome, John J. Miller, MD, explains.

Dr Miller is Medical Director, Brain Health, Exeter, NH; Editor in Chief, Psychiatric Times; Staff Psychiatrist, Seacoast Mental Health Center, Exeter, NH; Consulting Psychiatrist, Exeter Hospital, Exeter, NH; Consulting Psychiatrist, Insight Meditation Society, Barre, MA.