NROB60H3 Chapter Notes - Chapter 1: Luigi Galvani, Andreas Vesalius, Ventral Root Of Spinal Nerve
11 Jun 2018
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Chapter 1- Neuroscience Past, Present, and Future
• The Origins of Neuroscience
o The archeological record has many hominid skulls that have signs of fatal cranial damage that
other hominids inflicted on others like boring holes (called trepanation) ---this technique was
attempted to cure not to kill, therefore these procedures were performed before death
o They started to boar holes in an attempt to cure mental disorders and headaches by allowing
eil spirts to esape the raiu
o In ancient Egypt there were writings (5000 years ago) that show that they were aware of
symptoms of brain damage but they still believed that the heart contained the soul and
memories
▪ Even in the burial process they removed the brain and discarded it while the rest of the
body is preserved, Hippocrates was the first person to challenge the theory that the
heart was the center of consciousness
➢ Views of the Brain in Ancient Greece
o Different parts of your body look different because they perform different function but there is a
clear correlation between the structure and the function
o Hippocrates observed the brain and realized that the parts of the head have nerves (specialized
for sense) that go into brain therefore he concluded that the brain is and organ of sensation, he
also believed that the brain was important for intelligence
o Aristotle had the belief that the heart was still the center of intellect, he believed that the brain
was used as a cooling center and they thought the temperament of humans was based on their
ability to cool the brain
➢ Views of the Brain
o Galen looked at the injuries (spinal cord and brain) that gladiators suffered and he did many
animal dissections
▪ During these animal dissections he tried to deduce the function of the 2 major parts
(cerebrum and cerebellum) so he touched both the parts and realized that the cerebrum
was soft and the cerebellum was hard
▪ From that observation he thought that the cerebrum was responsible for sensation and
the cerebellum was responsible for muscle control
▪ He was fairly correct as the cerebrum is responsible for sensation and perception (and
MEMORY) and cerebellum is the motor control center
▪ Galen cut open the brain and realized that it was hollow and these spaces are hollow and
there was fluid and this is where he thought the different fluid (humors) travelled
through the ventricles and nerve (also thought to be hollow)
➢ Views of the Brain from the Renaissance to the Nineteenth Century
o Andreas Vesalius added more detail to the structure of the brain but the ventricular theory
remained unchallenged and when hydrolytic machines were built they thought the muscles flow
to usle to pup you up, like hy to usles ulge durig otratio
o Rene Descartes believed in the hydraulics theory but he believed that the full range of
behaviour as god-gie soul ad oly the aialisti side of huas is otrolled y the
brain
▪ He believed that the mind received sensations and commands by communicating
through the pineal gland
o Scientists realized that there are white and gray matter, and they thought the function of white
matter (since it was connected to nerves) brought information to and from the gray matter
o CNS and PNS, gyri and sulci, and lobes was discovered
➢ Nineteenth-Century Views of the Brain
o Nerves as Wires
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▪ Luigi Galvani and Emil du Bois-Reymond showed that muscles twitched when electrical
stimuli were applied to the nerved and that they brain itself can generate electricity
▪ These theories displaced the theory that nerves were used to carry fluid and instead
used to carry electrical stimuli
▪ Bidirectional communication was suggested to answer whether or not the same wires
were used to communicate between movement and registering sensations of the skin
▪ When a nerve is cut you realize that the the movement and the sensation to that area is
lost
▪ Each nerve has smaller filaments called nerve fibers and these each carry bits of
information to different places
▪ Charles Bell and Francois Magendie realized that before the nerves attach to the spinal
cord the fibers divide and the dorsal root enters the back of the spinal cord and the
ventral root enters the front and to find the function of each of the roots they were
severed to observe function
▪ the served ventral roots resulted in muscle paralysis and the severed dorsal roots was
responsible for carrying sensory information
▪ in sensory and motor nerve fibers the transmission is strictly one-way
o Localization of Specific Functions to Different Parts of the Brain
▪ Bell proposed that the origins of the motor fibers are in the cerebellum and the origins of
the sensory fibers are in the cerebrum to find out you could use a experimental ablation
method which involves destroying an area to determine the function
▪ Marie-Jean-Pierre Flourens used this method on animal and birds to show that the
cerebellum was important for the coordination of movement and he concluded that the
cerebrum was involved in sensation and perception
▪ Franz Joseph Gall believed that the bumps on the brain corresponded to the bumps on
the skull and he thought that each bump reflected one personality trait (called
phrenology)
▪ Fluorens discredited Gall by performing ablations to test personality traits and also said
that the bumps on the skull do not means that there are bumps on the brain
▪ Paul Broca had a patient who could understand language but could not speak and he
examined his brain after he died and realized that he had a lesion on an area which is
responsible for speech production
▪ Gustav Fritsch and Eduard Hitzig realized that applying electrical currents to certain
regions if a dog’s brain can allow the dog to perform discrete movements
▪ David Ferrier repeated this experiment with monkeys but he decided to remove that
area and show that it resulted in muscle paralysis
▪ Hermann Munk said experimental ablation to find out that the occipital lobe controlled
vision
o The Evolution of Nervous Systems
▪ Charles Darwin developed the theory of evolution saying that all species developed from
a common ancestor and he explained that the difference in species exist because of
something called natural selection
▪ The physical traits between a parent and a child may be different because the physical
traits the child has is more advantageous for survival and these advantageous traits get
passed onto the next generation
▪ Darwin also believed that behavior could be a heritable trait because many mammalian
species have similar reactions to being scared (e.g. pupil dilation, heart rate, hairs stand
on end) and since these traits are similar these traits came from a common ancestor that
used these traits to survive therefore it was passed down to us
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