NATS 1860 Study Guide - Midterm Guide: Sushruta Samhita, Cerebral Cortex, Retina

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18 Oct 2012
NATS 1860 Keywords and Definitions
- Localization theory: The core definition is the idea that different structures of
the brain should have different functions. This theory starts with the brain as
a whole, and narrows specific structures with specific functions. The first
sign of considered localization theory was historically shown to be in circa
16th century BCE (through the Edwin Smith Papyrus), when Egyptian scribes
noted that patients who were stricken on the head had a loss of balance.
Localization was taken into a more serious consideration during 4th century
CE when Nemesius, bishop of Emesa, proposed through the ventricle theory
that the three cavities in the brain were localized, and that each of these
cavities served a particular function; perception, cognition and memory. The
localization theory is also the main theme of our look at the history of
- Trepanation: Medical procedure in which a hole or series of holes is removed
from the skull for medical or traditionally religious purposes. Trepanated
skulls first discovered are dated to be over 10,000 years old and oldest skulls
were discovered from within the Neolithic region. Alexandre Francois Barbie
du Botage was the first to notably analyze the process of trepanation. The
process of trepanation was adapted in such countries as Mesopotamia,
Ancient Idea, Ancient China, Native Peru and Spain. Based on archeogical
discoveries, scientists have been able to determine the percentile of survival
rate being 63% based on skulls having a smooth texture (in the holes)
indicating a healing process occurred. However, as of the 20th century it was
replaced by psychosurgery and drug therapy. The most recent case of
trepanation was present in 1970 by Amanda Feilding, a young woman in the
Bart Hugus Amsterdam experiment, in which she engaged trepanation as a
method of hallucination.
- Edwin Smith surgical papyrus: It is a Papyrus bought by Edwin Smith in the
late 19th century and then translated by James Breasted in the early 20th
century. This papyrus was most likely written in 17th century BCE, and it
describes Ancient Egyptian Clinical cases. This is important to Neuroscience
because it told us that even in civilizations such as Ancient Egypt, they were
using clinical cases to localize which kinds of head injury caused which kinds
of movement impairment. This is important because it shows that
localization theory was considered a possibility since Ancient Egypt. For
example, In the Edwin Smith Papyrus there are many cases in which an
individual is stricken on the head, and then they are unable to stay balanced.
This lead to question if there was any specific function of the brain, which
caused people to maintain their balance.
- Humoral theory: It’s a theory that states that the human body is made up of
four humours; air (represented in the form of blood), water (represented in
the form of phlegm), earth (represented in the form of black bile), and fire (in
the form of yellow bile). It was the first essential framework for
understanding and curing disease. Essentially, in order to cure the body, you
had to “balance out” all the humours, and this usually meant bleeding to
remove too much of an air element in order to equalize all the other
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elements. Hippocrates considered this theory sometime in the 5th-4th century
BCE, and it’s a holistic approach to medicine, which suggests that the body
works as a whole as opposed to the theme of our course, specialization,
which suggests that every part has a specific and unique function.
- Ventricular localization: The theory that there were three large cavities in the
brain that were filled with cerebrospinal fluid as well as animal spirits, which
moved along through the muscles through nerve pathways, which were
considered to be hollow. Galen first proposed this theory sometime in 2nd
century CE. Later, Nemesius, the bishop of Emesa (4th century CE) proposed
that perception was part of the frontal ventricle, cognition was part of the
middle ventricle, and memory was in posterior ventricles. Therefore, this is
important to our course because it shows the very first specific thoughts
about localization, and that different parts in the brain have different
- Andreas Vesalius: He was an anatomist and physician during the 16th century
CE who wrote the di humani corpus fabrica, a very influential book in the
progress of neuroscience because it offered a very detailed sketch of the
brain and the different layers, ridges, and bumps in the brain. Vesalius is an
important character in our study of the history of neuroscience because his
works urged a re-examination of past medical beliefs based on anatomy,
meaning it urged neuroscience to progress forward, instead of wasting time
pondering on incorrect theories.
- Descartes: A French philosopher who lived in the 16th-17th century CE, he
came up with a theory of involuntary movement, which suggested that
animals are like machines because there is a constant flow of animal spirits
through the “valvules” in the hollow nerves. At the same time, he also said
that what makes humans more advanced than other animals is that to our
involuntary movements, we also have rational movements, which instead of
animal spirits are controlled by a rational soul that is stored in the pineal
- Automaton: A mechanical robot which was usually operated by a series of
mechanisms, intertwined with each other, and functioning in order to move
the robot. Each mechanism has a specific amount of gears, without which the
robot will be unable to move. Rene Descartes compared human beings to
automatons in the sense that we’re all just a bunch of tubes (nerve valvules)
and that the animal spirits seeping through us controls our movements.
Automatons are great examples of how neuroscientists believe the
localization theory works in the sense that there must be specific parts
(mechanism) in the brain, which causes a specific function to happen.
- Bell-Magendie Law: The law stated that there had to be some form of
separation of the motor and sensory roots in the spinal cords. This law was
proposed by Bell and Magendie (hence the name) in the late 18th century and
was discovered by the process of lesions and stimulations within the brain.
Essentially, there was a crude form of electricity in the form of an electrode,
which was prodded into different parts of the spinal cord to see what
reaction would occur. This law is important to neuroscience because it shows
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