NROB60 – Chapter 1
Origins of Neuroscience:
- Trepanation – the process of boring holes into people’s skulls with the aim to cure.
Views of the Brain in Ancient Greece:
- There is a very clear correlation between structure and function
o Differences in appearance predict differences in function
- Hippocrates (460-379) – stated his belief that the brain not only was involved in
sensation but also was the seat of intelligence.
- Aristotle (384-322) – clung to the belief that the heart was the center of intellect
o He reserved the function for the brain as a radiator for the cooling of blood that
was overheated by the seething heart
View of the Brain during the Roman Empire:
- Galen (130-200) – embraced the Hippocratic view of brain function
o Influenced by animal dissections
o 2 major parts were evident:
Cerebrum in the front and rather soft
• Recipient of sensations & perceptions, repository of memory
Cerebellum in the back and rather hard
• Command the muscles, movement control center
o Hollow spaces in the brain
Ventricles, that have fluid
• The body functioned according to the balance of 4 vital fluids or
View of the Brain from the Renaissance to the 19 Century:
- Descartes (1596-1650) – reasoned that unlike other animals, people possess intellect
and a god given soul. He proposed that brain mechanisms control human behaviour
only to the extent that this behaviour resembles that of the beasts.
- Other scientists found that the brain tissue is divided into 2 parts:
o Gray matter – n/a
o White matter – continuous with the nerves of the body, believed to contain the
fibers that bring information to and from the gray matter
- There are general pattern of bumps and grooves on the surface of the brain in every
individual and this pattern enables the packaging of the cerebrum into lobes.
o Bumps = gyri
o Grooves = sulci and fissures
19 Century Views of the Brain:
Nerves as Wires:
- Benjamin Franklin – published a pamphlet titled Experiments and Observations on
Electricity, which foreshadowed a new understanding of electrical phenomena.
- Galvani and Emil du Bois-Reymond – showed that muscles can be caused to twitch
when nerves are stimulated electrically and the brain itself can generate electricity.
o These discoveries displaced the notion that nerves communicate with the brain
by the movement of fluid. - New concept was that the nerves are wires that conduct electrical signals to and from
o Suggested when a nerve in the body is cut, there is usually a loss of both
sensation and movement in the affected region.
o It is known that within each nerve of the body there are many thin filaments, or
Each one can serve as an individual wire carrying information in a different
- Charles Bell and Magendie – Just before the nerves attach to the spinal cord, the fibers
divide into two branches, or roots.
o The dorsal root enters toward the back of the spinal cord
Carries sensory information into the spinal cord
o The ventral root enters toward the front
Cutting only the ventral roots caused muscle paralysis
Localization of Specific Functions to Different Parts of the Brain:
- Bell (1811) – proposed that the origin of the motor fibers is the cerebellum and the
destination of the sensory fibers is the cerebrum.
o This could be tested using the approach of destroying parts of the brain and
testing for sensory and motor deficits.
This approach, in which parts of the brain are systematically destroyed to
determine their function, is called the experimental ablation method.
- Flourens – used this method in animals and showed that the cerebellum plays a role in
the coordination of movement and that the cerebrum is involved in sensation and
- Gall – proposed that the propensity for certain personality traits could be related to the
dimensions of the head. (Ex. The bumps)
o The new science of correlation the structure of the head with personality traits
was called phrenology.
- Broca – found a lesion in the left frontal lobe of a patient who could understand
language but not speak.
o He concluded that this region of the human cerebrum was responsible for the
production of speech.
- Fritsch and Hitzig – showed that applying small electrical currents to a circumscribed
region of the exposed surface of the brain of a dog could elicit discrete movements.
- Hermann Munk – used experimental ablation to present evidence that occipital lobe of
the cerebrum was specifically required for vision.
The Evolution of Nervous System:
- Charles Darwin – differences among species arise by a process called natural selection
o As a result of the mechanisms of reproduction, the physical traits of the offspring
are sometimes different from those of the parent
- Many neuroscientists use animal models to examine the process they wish to
understand in humans
o Ex. rats used to understanding how psychoactive drugs exert their effects on the
The Neuron: the Basic Functional Unit of the Brain: - Schwann – proposed the cell theory; all tissues are composed of microscopic units
o Nerve cells have a number of thin projections, or processes that extend from a
central cell body.
o The individual nerve cell is now called the neuron and is the basic functional unit
of the nervous system.
- Understanding how the brain works is a big challenge; neuroscientists break it into small
pieces for systematic experimental analysis called the reductionist approach.
o The size of the unit of study defines what is often called the level of analysis.
o In ascending order, these levels are molecular, cellular, systems, behavioural,