Chapter 1 History and Introduction
The brain is like a muscle.
When it is in use, we feel very good.
—Carl Sagan (Astronomer, Cosmologist, and Author)
The human brain is made of about 85 billion cells called neurons that send and receive signals from thousands of other neurons. The brain also has billions of other cells called glia that bind the neurons together, provide them with food and oxygen for energy, get rid of waste, help in communication, and function in hundreds of different supporting roles. The complexity of billions of cells communicating together and getting feedback from the body and the environment creates, as physicist Michio Kaku said, “the most complex object in the solar system” (Kaku, 2015). People have been studying the brain for centuries, but in the past 50 years there have been incredible advancements in brain imaging, genetic analysis, biochemistry, and psychology that have helped researchers begin to unravel the mysteries of the brain. In many ways, however, we are just at the beginning. Through this textbook, you’ll get a foundation of what we’ve learned so far and what’s happening today, and maybe a glimpse into what could happen in the near future.