BREAKTHROUGHS IN THE STUDY OF THE HUMAN BRAIN

he human brain has been the subject of study since the earliest of times, although ancient Egyptians didn’t consider it to be worth much. Archaeologists found that Egyptians removed and discarded the brain before mummifying the dead. Aristotle considered the brain to be a secondary organ that served to cool the heart. In the Middle Ages, the brain was believed to have “ventricles” or sections that contained imagination, thought and memory. However, study of the brain progressed through the centuries, with small, incremental discoveries and with great leaps forward.[1]

Classical Discoveries
Hippocrates: Around 400 B.C. Greek physician Hippocrates established a medical school on the Aegean island of Cos.[2] His more than 70 medical works were collected in the “Corpus Hippocraticum.” He observed that head injuries often resulted in deficiencies in thought and the senses, and wrote that the brain is involved with sensation and is the seat of intelligence. He observed that human brains, like those of many animals, had two sides divided by a thin membrane.[3] 
Herophilus of Chalcedon: Around 300 B.C. Herophilus of Chalcedon, who had studied at the medical school on Cos, identified several structures of the brain including what we now call by their Latin names, the cerebrum and cerebellum.
Galen of Pergamon: Around 77 A.D. Galen of Pergamon, having dissected animals, assumed that the structure of the human brain must be different from those of animals, but was responsible for motor control and interpreting sensory input. His teachings were the foundation of anatomical knowledge for centuries. [4]

Renaissance Neurology
In some European countries during the 1500s, anatomists were allowed to use live criminals and the cadavers of executed criminals to study human anatomy and function. Belgian anatomist Andreas Vesalius took advantage of this freedom to carefully dissect human brains. He contradicted Galen regarding the “ventricles” of the human brain, observing that they resembled those of animals and wrote that they must serve similar functions. In 1664 Thomas Willis, a physician in Oxford, England, described in text and highly-detailed drawings many structures in the brain including the corpus callosum, the band of fibers that connects the two hemispheres of the brain. He coined the word “neurology”

Advances of the Enlightenment
In the late 1700s, Luigi Galvani, an Italian physiologist, triggered movement in frog muscles with electricity. From these experiments he suggested that nerve cells conduct electricity to the muscles.[5] In the early 1800s, Scottish surgeon Thomas Bell traced the nerves from organs to their point of origin in the brain, showing that the function of the organs is indirectly controlled by the brain. London physician In 1817 James Parkinson published “An Essay on the Shaking Palsy” describing the neurological origins of the syndrome that bears his name.

Modern Discoveries.
In the late 1800s understanding of neurology progressed rapidly. In 1848, Phineas Gage, a railroad worker survived having a railroad spike through his brain. Following this accident his personality changed from that of a good-natured worker to a surly malcontent who was never able to keep a job. Gage’s transformation showed that aspects of personality must originate in the brain. Paul Broca observed that the speech center – now called “Broca’s Area” — was located in the left frontal area of the brain. In 1891: Santiago Ramon y Cajal showed that the nerve cell (the neuron is the elementary unit of processing in the brain, receiving inputs from other neurons via the dendrites and sending its output to other neurons via the axon.

Today’s Information
Since the middle of the 20th century, neuroscience continues to gain a better understanding of the brain. During the 1950s, Otto Loewi, Henry Dale, Wilhelm Feldberg, Stephen Kuffler, John Eccles and Bernard Katz studied and described the chemical basis of transmission between synapses. Arvid Carlsson identified the neurotransmitter, dopamine, and proposed its role in Parkinson’s disease.[6] From the early 1900s to the present day, research into movement disorders has produced valuable treatments including levodopa to treat Parkinson’s disease [7] and surgical procedures such as deep brain stimulation for movement disorders like Parkinson’s and Essential Tremor.[8]

RESOURCES
Medline Plus: Medical Dictionary
 
REFERENCES
[1] A History of the Brain
[2] Encyclopedia of World Biography
[3] The Journey of Discovering Skull Base Anatomy: Rise of the Greek Empire in Ancient Egypt
[4] The Journey of Discovering Skull Base Anatomy: Galen of Pergamon: AD 129–199
[5] The Secret Life of the Brain: History of the Brain
[6] A Timeline of Neuroscience Research
[7] Levodopa in the treatment of Parkinson’s disease: an old drug still going strong
[8] Wake Forest Baptist Medical Center — Deep Brain Stimulation: History of DBS