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Biology 463 - Neurobiology
Topic 1
Neuroscience: Past,
Present, and Future
Lange
Introduction
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Virtually all aspects of human nature & behavior are governed by the
nervous system:
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Curiosity,
Pain,
Pleasure
Movement
Reasoning
Learning
Memory
Emotion
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Neuroscience
– The formalized study of the nervous system and how it develops, how it
is organized, and how it functions.
•
The Society for Neuroscience
Trepanation is
the purposeful
cutting of a hole
into the skull.
It is presumed that this individual received this surgery to combat some sort
of psychosis, although other causes could be explanations as well.
The Society for Neruoscience (SfN):
SfN's Mission:
1.
Advance the understanding of the brain and the nervous system by bringing together
scientists of diverse backgrounds, by facilitating the integration of research directed at all levels
of biological organization, and by encouraging translational research and the application of new
scientific knowledge to develop improved disease treatments and cures.
2. Provide professional development activities, information, and educational resources for
neuroscientists at all stages of their careers, including undergraduates, graduates, and
postdoctoral fellows, and increase participation of scientists from a diversity of cultural and ethnic
backgrounds.
3. Promote public information and general education about the nature of scientific discovery and
the results and implications of the latest neuroscience research. Support active and continuing
discussions on ethical issues relating to the conduct and outcomes of neuroscience research.
4. Inform legislators and other policymakers about new scientific knowledge and recent
developments in neuroscience research and their implications for public policy, societal benefit,
and continued scientific progress.
Brief History of the Origins of Neuroscience:
• Ancient Egypt - symptoms of brain injuries were noted, but the heart
was considered the seat of emotions and the “soul”.
• Ancient Greece - Hippocrates & Aristotle were the primary
philosopher/scholars that defined the view of the brain during this
period.
• Roman Empire - Galen’s writings and work defined the view of the role
of the brain during this period.
• Renaissance Period – 1700’s – Vesalius and Descartes shaped the
changes in understanding of the brain during this period.
• late 1800’s to the present, major development in understanding of the
nature of the nervous system.
Hippocrates (460-379 B.C.E.) – first ascribed to the brain the role of
the organ of sensation and the seat of intelligence.
Aristotle (384-322 B.C.E.) – felt the heart was the center of
intellect and believed the brain was more akin to a
“radiator” to cool the body.
Galen was one of
the earliest
scientists to perform
significant animal
dissection leading to
the field of
comparative
anatomy.
Galen (130-200 A.D.) – Greek physician who tried to deduce function of
the brain from structure of the cerebrum and cerebellum. He put forth a
model for brain function that was the start of the fluid-mechanical theory.
In Galen’s dissection work with sheep, he could feel physical differences in
the texture of the cerebrum and the cerebellum. The cerebrum was softer,
and more “spongy” than the firmer cerebellum.
With this discovery, he proposed that the cerebrum was the area receiving
sensations because it needed to be pliable and flexible, whereas the rigid
cerebellum controlled the musculature.
•
Views of the Brain: The Roman Empire
– Views of Greek physician Galen
• Cerebrum
• Cerebellum
• Ventricles
In the period of time from the Middle Ages into the early Reniasance, few
changes or advancement in our understanding of the brain occurred.
Most historians attribute the lack of growth in understanding of the brain
during that time to the significant taboo on exploring the internal workings
of the human body via dissection during that age.
Annonymous painting from the 1300’s (Middle Ages) showing a surgeon
and monk suggesting the prohibition on dissection.
Andreas Vesalius – publishes On the Workings of the Human Body in
1543… an enormously influential work during a period where it was
still considered very taboo to engage in exploration of the internal
workings of the human body.
Another example of one of his drawings. Notice the very precise
drawing style and the quality of the drawings.
Rene’ Descartes – (1596-1650) considered one of the most significant of
the Western Philosophers and Scientists during his time. He promoted
the idea of the brain function occurring via the fluid-mechanical theory….
especially for NON-HUMAN animals.
He believed that a human’s soul necessitated other methods to explain
human neural function and behavior.
Descartes
ascribed special
fluid moving
powers to the
pineal gland
(letter “H”) .
From Galen’s time through
Descartes, the major emphasis on
study of the brain focused on the
ventricles, and tended to ignore or
diminish potential roles for the tissue
of the brain itself.
Grey & White Matter:
When the tissue portion of the brain began to be more closely examined during
the Renaissance, the focus shifted to examining tissue from the standpoint of
the two visible color differences seen in the brain. These colors were readily
observable in both fresh and preserved specimens. We use the same terms to
name these different portions to this day…. grey and white matter.
The hypothesis of that age on the function of these two distinctly different areas
was that:
a.
White Matter, because it is similar in color and appears contiguous with the
nerves in the peripherial body, serves to connect the brain and spinal cord
to the nerves.
b.
Grey Matter, lying outside on the surface regions of the brain and spinal
cord, is going to receive information from the periphery directly through
interaction with the White Matter.
These ideas are reasonably aligned with our current understanding of how
these tissue areas function.
• Overall views of the Brain During The
Renaissance
– The brain as a machine – Vesalius
– Fluid-mechanical theory of brain function - Descartes
– Philosophical mind-brain problem – Descartes (How do you meld
the physical, observable tissues of the brain/nervous system with
the philosophical/religious ideas about the soul?
BUT, by the mid to late 1700’s there was a relatively well known
body of knowledge in the dissected anatomy of the brain
including gyri, sulci, and fissures.
Gyrus – “hill”-like area of tissue
Sulcus – “valley’-like area of tissue
Fissure – an especially deep sulcus
CNS – central
nervous system….
brain & spinal cord
PNS – peripheral
nervous system…
basically everything
else
Benjamin Franklin publishes Experiments and Observations on
Electricity in 1751. His notions on electricity paved the way for a new
theory of neural function that prevailed in the 1800s.
Luigi Galvani
Emil du Bois-Reymond
These two researchers were responsible for
determining the interaction
between electricity and the brain.
Du Bois – Reymond
later in life.
Using electricity, Du Bois-Reymond was able to demonstrate a clear
link between the contraction of muscle tissue and electricity. He
proposed that this was the way in which nerves functioned in the body.
Du Bois – Reymond’s work generated worry and fear in the
general population at many levels.
Charles Bell
Francois Magendie
These two conducted experiments that answered the question
on whether the movement in a nerve was bidirectional or
unidirectional.
They saw that the nerves of the PNS will divide into two
branches (ROOTS) just before merging with the CNS.
• Overview of the
Brain: The Nineteenth
Century
–
Nerve as wires,
understanding of electrical
phenomena, nervous
system can generate
electricity
–
Bell and Magendie: Dorsal
and ventral roots carry
information in opposite
directions
These two roots (dorsal and
ventral) carry information in
different directions.
Basically the ventral roots carry
information out to the PNS to
engage motor function. The
dorsal roots transmit PNS
sensory information into the
spinal cord.
Franz Joseph Gall (1758-1828) was the founder of phrenology.
Phrenology is a
pseudoscience
primarily focused on
measurements of the
human skull, based
on the concept that
the brain is the
organ of the mind ,
and that certain
brain areas have
localized, specific
functions.
Phrenology was
especially popular
from about 1810 until
around 1840.
Ablation – a technique to
eliminate or destroy tissue. In
neuroscience, the origins of this
technique occurred in bird
studies, whereas today rodent
studies are the most prevelant.
Marie-Jean-Pierre Flourens
Famous for the
development of the
experimental ablation
method.
Franz Joseph Gall
Paul Broca
Gall described the concept of phrenology –
looked at the external skull (now discredited)
Broca first identified a region of the cerebrum being associated with function –
focused on the internal gyri and sulci of the cerebrum.
This left frontal lobe lesion (a nonexperimental ablation) resulted in the
inability to speak, showing a specific
localized function for a region of the
brain.
What is especially valuable in
Darwin’s work relative to
neuroscience is his inclusion of
BEHAVIOR among the heritable
traits shaped through evolution.
The very notion that many animals
display a similar behavioral response
to a similar stimulus suggests further
a common ancestor.
This is a very basic tenet of the
current state of research in
neuroscience and exemplifies why
animal experimentation is so
valuable.
Charles Darwin – his theory of natural selection helped to
explain the growth and development of the brain.
However, it must
also be understood
that there can be
unique
specializations that
can evolve in
species relative to
behavior .
Specialized visual
center in the
monkey is show
compared to a
specialized region
for smell in the rat.
• So, for the evolution of the nervous
system:
– Natural selection
– Nervous systems of different species will share many
common mechanisms
The emergence of the CELLULAR
study of the nervous system:
•The 1800s also heralded in the start of the age of a
cellular look at the nervous system.
•The cellular approach significantly contributed to
understanding of the system and complemented
many of the prior paths of research into the function
of the brain.
Theodor Schwann proposed the cell theory…. ALL TISSUES ARE
COMPOSED OF CELLS
This laid the groundwork for the tremendous molecular advances
in neuroscience occurring today.
Otto Deiters (1865) – identified the major parts of the neuron
and predicted the communication and interaction
between the axon and dendrites.
An example of Otto Deiters
drawing of a neuron.
Neuroscience Today
We who study neuroscience, like most all of science, will follow what is called a
reductionist approach in our study:
Reductionism in science means:
•
an approach to understanding the nature of complex things by reducing them to the
interactions of their parts
and/or
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a philosophical construct stating that a complex system is nothing but the sum of its
parts
– Levels of analysis
• Molecular
• Cellular
• Systems
• Behavioral
• Cognitive
Levels of Analysis can be
applied to Neuroscience
The Use of Animals in Neuroscience
Research:
• Examples (from simple to more complex) nematodes, insects, snails, squid, rodents,
monkeys, etc.
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Animal rights
Philosophy
Abolition of animal use
Animal rights activists
• The Neuroscientist
-Education, Training, Research experience
-Clinical vs. Experimental research
• Nervous System Disorders
END.