Brains: Milestones of Understanding
Snappy Page Essence
Brains are the chief mediators of thoughts, feelings and behaviours; we cannot fully understand our relationship to animals at least until we know what is going on in them.
The brain is the chief mediator of thoughts, feelings and behaviour in animals. The brain, therefore, is the physical font of ethics and we will not fully understand our relationship to animals at least until we know what is going on in their brains and can compare them with what goes on in our brains.
Discovering how the brain works began slowly and scientists discovered the basis of how it functions only during last century. The brain sends electrical impulses along fibres with chemical transmission between fibres.
When reading any history of discoveries about the brain (of which just a few are recorded here) bear in mind the pain and suffering endured by vivisected animals � and vivisected humans until human vivisection was banned - especially before pain killers were discovered in the 19th century.
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Left to right: human, rhino and dolphin brains. Photo: Escaladix.
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6,000 years before present
The first known record about the brain, or at least about an influence on the brain. It is a description about the feeling of well-being after swallowing parts of the poppy plant. Someone wrote the record in cuneiform on tablets in Sumeria in the Middle East. The opium poppy,
Papaver somniferum, was grown from early times as a source of opium and is now cultivated around the world for its mind-bending euphoric influence.
4,500 years before present
First written account of the brain, in ancient Egyptian on papyrus by an anonymous physician. He describes in a non-mystical rational way the anatomy of the brain, cases of injury to it, resultant changes to other parts of the body and treatment of these injuries. The document is the
Edwin Smith Surgical Papyrus, named after the American Egyptologist who discovered it in Luxor, Egypt, in 1862. The papyrus dates from the 17th century BC and is a copy of an earlier manuscript from about 2500 BC.
2,450 years before present
Alcmaeon, a physician and philosopher living in the foot of Italy, is one of the first people to base his ideas on animal vivisection. He concluded from his dissection work that the brain is the main organ of thinking and feeling, an idea that Plato approved. People had accepted that thinking and feeling were the job of the heart.
2,300 years before present
Herophilus and Erasistratus, of Alexandria, wrote a detailed account of the anatomy of the brain. They vivisected criminals and were the first to compare dissections of humans with animals. Herophilus discovered the nervous system and distinguished sensory and motor neurones. The study of anatomy stopped after the pair died, possibly because people thought the dissection of humans debased the dead.
Post Roman Era to 10th Century
At the end of the Roman Empire the Church banned human dissection and the study of anatomy. Discoveries about the brain largely cease until at least the 10th century and essentially for a number of centuries more.
1543
Andreas Vesalius (1514 - 1564), a Fleming, published an early textbook on neuroscience,
De Humani Corporis Fabrica (
On the Workings of the Human Body). One of his discoveries is that animal and human brains have the same ventricles, certain cavities. For centuries after people assumed these ventricles were the base of mentality. But Vesalius inferred that the ventricles were not involved in 'higher' functions, like memory and emotion, since animals have no
soul. Vesalius dissected away entire live animals, as well as dead humans. Anatomists look upon him as the founder of modern anatomy and still prize his illustrations.
1664
Thomas Willis (1621 - 1675), a professor at Oxford University, published the first monograph,
Cerebri Anatome, on the structure and function of the brain and central nervous system. Thought, according to Willis, is a product of the cerebral hemispheres; other parts of the brain control movement, like eating and walking.
1791
Luigi Galvani (1737 - 1798) was a surgeon and physiologist at the University of Bologna. Following his study of twitching in legs detached from dead frogs, he proposed that electricity flows through nerves to make muscles contract. He claimed nerves were not pipes or channels, as contemporaries thought, but were electrical conductors. This marks the beginning of our understanding of electricity in the nervous system.
1848
Phineas Gage (d 1860) was a railway worker in Vermont, USA. During an explosion at work a big iron bar pierced right through the front of his brain. The bar weighted 6kg (13 lbs) and was a metre (3 ft) long. Gage survived and became a medical celebrity. After he was hit by the bar he suffered severe personality changes, suggesting that the front of the brain is involved with personality.
1875
Richard Caton (1842 - 1926), a British physician, published the results of his discovery of electrical activity in the brain after exposing and exploring the brains of animals.
1906
Santiago Ramon y Cajal (1852 - 1934), a Spaniard, applied a method to show the existence of brain cells. He was the first to isolate nerve cells and their connections on the surface of the brain and showed they are the basic units of the nervous system. For his research he won the Nobel Prize.
1929
Following on from the findings of Richard Caton in 1875 (above), the first electrical signals from a human brain were transcribed and recorded by Hans Berger (1873 - 1941), a German psychiatrist. He found some signals were associated with mental concentration and others with sleep. Berger coined the name electroencephalograph, or EEG, for the apparatus which picks up, amplifies and records electrical signals from the brain.
1963
John Carew Eccles (1903 - 1997), an Australian physiologist, and co-workers shared the Nobel Prize for showing how an electric impulse can travel along a nerve fibre. An electric impulse in a neurone stimulates the release of a substance (a neurotransmitter) into a tiny gap between it and neighbouring neurones, thus transmitting electrical impulses through the brain. Release of a different substance into the gap inhibits transmission between neurones.
1970
Julius Axelrod (1915 - 1998), American biochemist, shared a Nobel Prize with British and Swedish co-workers for discoveries about the storage, release, and inactivation of substances (neurotransmitters) which carry a signal from one neurone to the next. Their work was essential for understanding the transmission of signals in the nervous system among neurones and between neurones and organs, like muscles.
1970's Onwards
Now we are able to see inside the living working brain. CAT (Computerised Axial Tomography) takes images of different layers of the brain. MRI (Magnetic Resonance Imaging) employs radio waves and powerful magnets to show the brain in action when a subject does something. PET (Positron Emission Tomography) shows up areas of the brain receiving more blood, as when the brain performs certain functions. Computers convert electrical impulses from these tools into pictures for inspection and interpretation.
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