The great Greek philosopher and scientist Aristotle believed that our consciousness, imagination and memory was rooted in the human heart. It was a belief he shared with the ancient Egyptians, whose Book of the Dead endorses carefully preserving the heart of a mummy, but recommends scooping out and discarding the brain. Today, the supreme role of the heart lives on only as a metaphor for our intuitive, emotional selves.
There is evidence, however, that at least some Egyptians knew about the importance of the brain. The Edwin Smith Papyrus, dating back to 1700 BC, is the earliest known medical text in history. The papyrus discusses the brain, the meninges, the spinal cord and cerebrospinal fluid. It contains details of 48 medical cases, including seven that deal directly with the brain, which indicate that the Egyptian author knew the brain controls movement. However, the serious cases of brain injury are described in the papyrus as untreatable.
We have come a long way since ancient Egypt. We now know the parts of the brain responsible for many of its functions; we can operate successfully on the brain, and use medication to effectively treat many neurological disorders.
Getting to this point hasn’t been easy. Have you ever heard of trepanation? It’s the once popular belief that cutting a hole in your skull would relieve pressure on your brain and lead to enlightenment. Or how about phrenology, popular in the 1800s? Phrenologists thought that you could learn everything you needed to know about someone’s character by measuring the shape of his or her skull.
These missteps aside, neuroscience has advanced like most sciences: one small step after another — until the 20th century, when it flies into a sprint.
- 170 B.C. the Roman physician Galen, whose day job was fixing up gladiators, insists that a person’s temperament and bodily functions are controlled by the brain. His theories are dominant for the next 1200 years.
- 1000 A.D. The great Islamic surgeon Abu al-Qasim al-Zahrawi describes several treatments for neurological disorders in his 35-volume encyclopedia of medical practices, the Kitab al-Tasrif.
- 1543 The first true medical textbook to deal with neuroscience, “On the Workings of the Human Body,” is published by Andreas Vesalius.
- 1649 The French philosopher René Descartes comes up with the influential idea that while the brain may control the body, the mind is something intangible, distinct from the brain, where the soul and thought resides. This concept is still with us, much to the chagrin of many neuroscientists.
- 1664 Thomas Willis publishes “Anatomy of the Brain,” which describes reflexes, epilepsy, apoplexy and paralysis. He uses the term neurology for the first time.
- 1791 Italian physiologist Luigi Galvani proposes that nerves operate through electricity.
- 1837 J. E. Purkinje is the first man to describe a neuron.
- 1862 Paul Broca pinpoints the part of the brain necessary for speech, henceforth known as Broca’s area.
- 1878 William McEwen performs the first successful modern neurosurgery.
- 1911 Aptly named British neuroscientist Henry Head publishes “Studies in Neurology.”
- 1929 Hans Berger invents the EEG (electroencephalography), a device that measures electrical activity in the brain.
- 1932 Lord Edgar Douglas Adrian and Sir Charles S. Sherrington win the Nobel Prize for describing how neurons transmit messages.
- 1938 Isidor Rabi discovers nuclear magnetic resonance, facilitating the development of magnetic resonance imaging (MRI). Rabi’s discovery would go on to win the Nobel Prize in 1944.
- 1950 Karl Spencer Lashley determines that memory relies on several sites in the brain working together.
- 1970 The Society for Neuroscience is established.
- 1973 Candace Pert discovers opiate receptors in the brain.
- 1974 A mouse is the subject of the first nuclear magnetic resonance (NMR) scan.
- 1974 The first Positron Emission Tomography (PET) scanner is invented, providing visual information about brain activity.
- 1987 Prozac is introduced.
- 1990 George H. W. Bush declares the last decade of the 20th century as the Decade of the Brain.
- 1992 Functional magnetic resonance imaging (fMRI) is first used to map activity in the human brain. Neuroscience booms.
The rapid pace of developments in neuroscience facilitated by modern imaging techniques is astounding. Yet many of the most important questions regarding the brain have yet to be answered. Why do we sleep and dream? How does the chemical and electrical activity in the brain result in consciousness? These and other questions will fuel neuroscience in the 21st century.