SIGN-283 Lecture 30:
27 Jul 2020
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Task 9 – The Brain
Brysbaert, Chapter 6 p. 217-265
During the turn of society towards science there was another stream of input,
consisting of the growing insight into the workings of the human brain and its
consequences for mental life. The journey starts in Ancient Egypt and Greece.
Ideas in Ancient Egypt and Ancient Greece
• Edwin Smith Papyrus: Documents from Ancient Egypt that contains short
descriptions of the symptoms and treatment of different brain injury – it was found
in 1862 and was presumably written around 3000 B.C.
• But the existence of the papyrus did not imply that knowledge contained in it was
widespread and most scholars were convinced that the heart was the seat of the
soul. This can be concluded from the fact that efforts were made to conserve it.
• Plato: He divided the soul into three parts (Tripartite Soul)
1. The highest part is situated in the brain and responsible for reasoning. It
directly came from the soul of the universe and was immortal.
2. The second part dealt with sensation, mortal and situated in the heart
3. The lower part dealt with appetite and was place in the liver
• Aristotle: He was convinced that the heart was the seat of the soul and
functioned as the counterbalance of the heart. They formed a functional unit in
which the brain tempered the heat and seething of the heart.
Egypt
Greece
• Galen (130-200 C.E.): Started to experiment with animals six
centuries after Aristotle and found in one of his experiments that
after severing nerves in the throat, a pig would stop screaming
but not breathing, which suggested that the voice comes from
the brain
o He dissected brains and published drawings of them
o The brain was not important for reason or emotion but
residence for the soul
o How did the brain communicate with the body?
▪ The soul lived in the solid parts of the brain and
produced and stored animal spirits (= spirits that were
thought to travel over the nerves between the ventricles
in the brain and the body)
▪ The ventricles were an apertures in the middle of the
brain which for a long time were thought to contain
perceptions, memories and thoughts
Renaissance, 17th and 18th Century
• Galen’s view remained the norm until the 18th century
• Andreas Vesalius (1514-1564) resumed Galen’s view and extended it onto
humans. He found three ventricles which functions became differentiated
o Front ventricle: Receives information from the senses (“common sense”)
o Second ventricle: In the middle and comprised thought and judgment
o Third ventricle: At the back and contains memory
• With the discovery of Galen’s texts researcher also regained interest in the
relationship between injuries and behavior. The physician von Grafenberg for
example concluded that brain damage can lead to speech problems.
• The focus gradually turned to the solid parts of the brain rather than the ventricles
• In the 17th century they started to pay attention to the difference between the
outer layer or the cerebral hemispheres and the layer underneath
• Thomas Willis (1664) was one of the first researchers to implicate the grey part
of the brain in the functions of memory
• Around the same time scholars started to doubt the existence of spirits in the
nerves and hypothesized that fluid flows in them
• Increased Interest in Reflexes: That some behaviors were elicited automatically
without voluntary intervention became the focus of interest.
o Galen had already discovered the same in animals and had ascribed
“sympathy” between the various body parts (→ sympathetic nervous system)
Renaissance
17th and 18th Century
o Descartes was also interested in reflexes because
they fitted within his mechanistic view of the body.
He argued that a reflex consisted of a sensory
impression which rushed to the brain and was
reflected back into a motor command. This process
was unconscious and involuntary. (1633)
o Procháska published a book in 1784 in which the
argued that reflexes were not controlled by the
brain but involved the spinal cord
• However, the new insights did not lead to improved treatment of brain injuries
The Breakthrough in the 19th Century
A series of five breakthroughs in t he 19th century irrevocably altered the model of the
brain and made modern neurophysiology possible.
1. The Discovery of the Cerebrospinal Axis
• The view since Galen was that the spinal cord functioned as a transmission
channel of the spirits and later the brain fluid
• This view became questioned when researchers began to realize that a body
remained functioning in a vegetative state when the hemispheres were taken
away or disconnected from the top of the spinal cord
2. Growing Focus on Reflexes
• Research started to pay more attention to the nature and function of reflexes
• Marshall Hall (1790-1857) introduced the notion of the reflex arc to refer to
the mechanisms involve in involuntary movements elicited by sensory stimuli
o His claim profited from the discovery shortly made before that there exist
two different types of nerves (afferent and efferent nerves)
o He further extended his concept from a simple physiological phenomenon
to a biological principle and insisted that all muscular function, with a small
number of exceptions, depend on reflexes controlled by the spinal cord
• Ivan Sechenov was one of some scholars who extended Hall’s reflex arc from
the spinal cord to the complete brain – he was Pavlov’s teacher
• Still, there was some doubt among some scholars (e.g. William James and
John Dewey’s) but Watson did not share their hesitation when he introduced
behaviorism as the science of the S-R reflex arc.
3. Localization of Brain Functions
• Are different psychological functions localized in different parts of the brain?
• Brain Equipotentiality Theory: states that all brain parts have equal
significance and are involved in each task – view till 19th century
• Localization Theory: states that brain processes are localized, meaning that
only part of the brain underlies a particular mental function
