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Neurobiology
Syllabus:
1. A brief history of neuroscience.
2. Brain cells – neurons and glia.
3. Membrane equilibrium, Nernst potential.
4. Action potential, Hodgkin and Huxley model.
5. Cable theory.
6. Electrical and chemical synapses.
7. Integration in dendrites.
8. The taste system, the olfactory system, the somatic senses, muscle sense and kinesthesia, the sense of balance, hearing,
vision.
9. Motor activity. Reflexes. Locomotion. Central pattern generators.
10. Communication and speech.
11. Specific transmitter systems.
12. Emotion.
13. Learning and memory.
14. The cerebral cortex and human behavior.
Suggested reading list:
G. Shepherd, Neurobiology
E. Kandel, Principles of Neural Science
D. Johnston i S. Wu Foudations of Cellular Neurophysiology
P. Nunez, Electric fields of the brain.
W.J. Freeman, Mass action in the nervous system.
A.Longstaff, Neurobiologia. Krótkie wykłady, PWN
G.G. Matthews, Neurobiologia. Od cząsteczek i komórek do układów, PZWL
Edwin Smith Surgical Papyrus – 1700 BC
(‘yś) - brain
The Creation of Adam (1508-1512), Sistine Chapel, Vatican, Rome
Meshberger, Frank Lynn. "An Interpretation of Michelangelo's Creation of Adam Based on
Neuroanatomy", JAMA. 1990 Oct 10; 264(14):1837-41.
Some steps in acquiring knowledge about the brain
4000 BC
Euphoriant effect of poppy plant reported in Sumerian records
2700 BC
Shen Nung originates acupuncture
3000 – 1700 BC
Ancient Egypt. First written record about the nervous system.
2000 BC
Skull trephination in the pre-Incan civilisations in South America
460-379 B.C.
Hippocrates states that the brain controls sensations, emotions and
movement and is the seat of intelligence
460-379 B.C.
Hippocrates discusses epilepsy as a disturbance of the brain
387 B.C
Plato believes that the brain is seat of mental process
335 B.C
Aristotle believes heart is seat of mental process
130 – 200 AD
Galen dissected brains (beginnings of the brain physiology). He also
proposed four bodily fluids: blood, yellow bile, black bile, and phlegm.
1543
Andreas Vesalius publishes Tabulae Anatomicae - anatomy of the nervous
system (and ribs!) The brain is the center of mind and emotion.
1673
Rene Descartes describes pineal gland as control center of body and mind
1792
Galvani discovers the electrical nature of the nervous activiy
1891
Cajal and others determine that the nervous system is composed of
independent nerve cells
1897
Sherrington – nerve cells communicate with each other through synapses
1920s
Langley, Loewi, Dale and others identify neurotransmitters
1940s
Shannon, Weaver i Wiener introduce concepts of information processing and
control systems (cybernetics).
1950s
Hodgin, Huxley, Katz and Eccles – precise recordings of electrical
signals with microelectrodes.
1950s
Mountcastle, Lettvin, Hubel and Wisel – single cell analyses reveal ‘units of
perception’ in the brain.
1960s
Integrative functions of dendrites are recognized.
1970s
Neuromodulator substances and second messangers are found
1970s
Computer imaging techniques permit visualization of brain activity patterns in
relation to sensation and cognition
1970s
Molecullar methods are introduced for analyzing genetic mechanisms and
single membrane proteins.
1980s
Computer models of nervous system functions (vision, language, memory,
logic)
1990s
„The decade of the brain”: emphasis on combining information from
different levels of analysis into integrated models of brain function and
disease.
2000 and later
Eric Kandel – understanding memory mechanisms
Artificial brain:
1cm2 - Blue Brain Project
Small mammal brain - C2 (IBM)
Mammal Inteligence - MoNETA: A Mind Made from Memristors
http://artificialretina.energy.gov/
Behavioural neuroscience: Rat navigation guided by remote control.
Sanjiv K. Talwar, Shaohua Xu, Emerson S. Hawley, Shennan A. Weiss,
Karen A. Moxon and John K. Chapin
Nature 417, 37-38(2 May 2002)
The levels of neuronal organization
m o to r
c entral
sensory
(b) Local populations, neuronal
networks
(b) Systems
motor
c ent ral
sensory
Dendrites
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(a) Behaviour
Soma
Axon
(c) Single cells
(f) Genes
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(e) Membranes, channels,
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(d) Synapses
The aim of neurobiology (and the course)
Identifying the elementary units at different levels of organization of
the nervous system and understanding the relations between different
levels.
Divisions of the nervous system
The nervous system is divided into the central nervous
system and peripheral nervous system.
The central nervous system is divided into two parts: the
brain and the spinal cord. The average adult human brain
weighs 1.3 to 1.4 kg. The spinal cord is about 43 cm long in
adult women and 45 cm long in adult men and weighs about
35-40 grams. The spinal cord is much shorter than the
vertebral column.
The peripheral nervous system consists of sensory
division and motor division. Sensory division consists of
peripheral nerve fibers that send sensory information to the
central nervous system. Motor division consists of nerve
fibers that project to motor organs.
Motor division is divided into two major parts: the somatic
nervous system and the autonomic nervous system.
The somatic nervous system contains nerve fibers that
project to skeletal muscle.
The autonomic nervous system is divided into the
sympathetic nervous system and the parasympathetic
nervous system.
Brainstem – pień
mózgu
Midbrain –
śródmózgowie
Pons – most
Medulla oblongata –
rdzeń przedłużony
Cerebellum - móżdżek
Diencephalon międzymózgowie
Thalamus wzgórze
Diencephalon międzymózgowie
Hypothalamus podwzgórze
Limbic system –
system limbiczny
Hippocampus hipokamp
Lateral ventricle
– komora boczna
Basal Ganglia –
zwoje podstawy
Caudate – jądro
ogoniaste
Basal Ganglia –
zwoje podstawy
Caudate – jądro
ogoniaste
Putamen – skorupa
Striatum –
prążkowie = jądro
ogoniaste + skorupa
Amygdala – ciało
migdałowate
Cerebral Cortex –
kora mózgowa
White matter –
isotota biała
Frontal lobe –
płat czołowy
Temporal lobe –
płat skroniowy
Cerebral Cortex –
kora mózgowa
Grey matter –
isotota szara
Parietal lobe –
płat ciemieniowy
Occipital lobe –
płat potyliczny
The Neuron Doctrine
Nerve cells in the cerebellum, as
observed by Purkinje in 1837
A large motoneuron in the spinal cord,
as observed by Deiters in 1865. Note
the single axon (axis cylinder),
dendrites and soma.
The Neuron Doctrine
Camillo Golgi (1843 - 1926) in his laboratory
Golgiego stain made nowodays
Based on large number of connections
between neurons Golgi assumed that the
laws of signals transmission cannot be
specified and he proposed the reticular
theory.
Original Golgi stain
The Neuron Doctrine
Santiago Ramon y Cajal (1852 – 1934)
Cajal developed the Golgi method and
applied it to many parts of the nervous
system in many animal species. He
realized that the entitiy stained by the
method is the entire nerve cell and he
proposed that nervous system is
composed of separate cells.
Retina. Cajal’s drawing (1900)
The Neuron Doctrine
Wilhelm Waldeyer, a profesor of anatomy
and pathology in Berlin published in 1891
a review in medical journal, stating that the
cell theory applies to nervous system as
well. He suggested the term ‘neuron’ for
the nerve cell and the theory became
known as the ‘neuron doctrine’
Heinrich Wilhelm von Waldeyer-Hartz (1836-1921)
The Nobel Prize in Physiology or Medicine 1906
The Neuron
Neuron types and size
Unipolar neurons
Bipolar neurons
Axon diameter
0,004 mm - 100 microns (.1 mm)
Hair diameter
0,02 mm do 0,08 mm.
Multipolar neurons
Axon length 1 mm - above 1 m
In humans:
About 1011 neurons in the brain
Każdy neuron ok. 104 połączeń
Average length of akson in the cortex 2 cm.
Total length of axons A = 2*109 m
Earth – Moon distance L = 4* 108 m
A/L = 5
Neuron terminology
Nerve cells which have
long fiberst that connect
to other regions of hte
nervous system are called
projection neurons,
principal neurons or relay
cells.
Nerve cells which are
contained wholly within
one region of the nervous
system are called intrinsic
neurons or interneurons.
Interneurons may not have
an axon.
Dendrites - terminology
Neurons usually have a
single axon and many
dendrites. Dendrites may
be apical or basal. The
basal dendrites emerge
from the base and the
apical dendrites from the
apex of the pyramidal cell
body.
Neuroglia (glia)
Glial cells
Glial cells are non-neuronal cells
that provide support and protection
for neurons.
Neuroglial cells are generally
smaller than neurons and outnumber
them by five to ten times.
Glial types and functions
•Astrocytes: biggest and largest in number. They surround
neurons and hold them in place. They supply nutrients and
oxygen to neurons. They regulate chemical composition of
extracellular space by removing excess ions, notably
potassium. They regulate neurotransmission by recycling
neurotransmitters released during synaptic transmission and
by surrounding synapses and preventing diffusion of
neurotransmitters.
•Microglia: They destroy pathogens and remove dead
neurons.
• Oligodendrocytes: They coat axons in the CNS with their
cell membrane forming a specialized membrane called
myelin sheath. The myelin sheath provides insulation to the
axon that allows electrical signals to propagate more
efficiently
•Schwann cells: Similar in function to oligodendrocytes,
Schwann cells provide myelination to axons in the PNS.
SM (sclerosis multiplex) - a disease in which oligodendrocytes are destroyed resulting in a
thinning or complete loss of myelin causing neurons not to be able to effectively conduct
electrical signals.
Albert Einstein’s brain
Einstein’s brain was removed within seven and a half hours
of his death and was preserved for scientific studies.
Einstein's brain weighed only 1,230 grams, which is less
than the average adult male brain (about 1,400 grams).
One of the differences that were found between Einstein’s
brain compared to others was increased number of glial
cells.
It is known from animal studies that as we go from
invertebrates to other animals and primates, as intelligence
increases, so does the ratio of glial cells to neurons.
It is hypothesized that glial cells (astrocytes) could
communicate and transmit chemical signals throughout the
brain.
EEG measurement from Albert Einstein. Princeton, 1950