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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. Electrical and chemical synapses.
6. Cable theory.
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. Specific transmitter systems.
11. Emotion.
12. Learning and memory
Suggested reading list:
G. Shepherd, Neurobiology
E. Kandel, Principles of Neural Science
D. Johnston i S. Wu Foundations of Cellular Neurophysiology
J. Nolte, Mózg człowieka, URBAN & PARTNER
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 that the heart is seat of mental process
130 – 200 AD
Galen dissects brains e.g. monkeys (beginnings of the brain physiology). He
also proposes four types of temperament based on bodily fluids (humors):
blood, yellow bile, black bile, and phlegm.
1543
Andreas Vesalius publishes Tabulae Anatomicae - anatomy of the nervous
system (and ribs!). He observes that nerves are not hollow. Considers the
brain to be the center of mind and emotion.
1649
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 (PET) 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
Eric Kandel – understanding memory mechanisms
Artificial brain: 1cm2 of the cortex - Blue Brain Project (EPFL)
2010s and later
Human brain simulations - The Human Brain Project (EU)
Systems of Neuromorphic Adaptive Plastic Scalable Electronics (SyNAPSE)
– cognitive computer with similar function to the mammalian brain (DARPA
- Defense Advanced Research Projects Agency)
John O'Keefe, May-Britt Moser and Edvard I. Moser - positioning
system in the brain (Nobel, 2014)
Tononi, Boly, Massimini, Koch - theory of consciousness
The levels of neuronal organization
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 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
(visceral) nervous system. The somatic nervous system contains nerve fibers that project to skeletal muscle. The
autonomic nervous system is divided into the sympathetic, parasympathetic and enteric nervous system.
Functional brain areas
Brainstem (pol. pień mózgu): most important
part of the brain.
Many motor and sensory nerves pass through it.
It regulates cardiac and respiratory function.
Reticular formation located in the brain stem
regulates central nervous system, maintains
consciousness and regulates sleep cycle. Injury
to the reticular formation can result in
irreversible coma.
Midbrain (pol. śródmózgowie): controls
muscle movement, eyes movement (eg.
saccades) and hearing. Its largest nucleus substantia nigra - produces dopamine.
Damage to this nucleus is linked to Parkinson's
disease.
Pons (pol. most): includes pathways that pass
information from the brain to the cerebellum and
includes nuclei regulating sleep and dreaming
(REM), respiration, swallowing, bladder control,
hearing, equilibrium, taste, eye movement, facial
expressions, facial sensation, and posture.
Medulla (pol. rdzeń przedłużony): is responsible for
involuntary functions: breathing, heart rate, blood
pressure and reflexes: swallowing, vomiting, coughing,
sneezing.
Olivary nuclei in medulla are involved in sound source
localization.
Functional brain areas
Cerebellum (pol. móżdżek): is responsible for
motor planning, coordination, precision of
movement and motor learning. It may also be
involved in some cognitive functions (verbal
working memory).
Functional brain areas
Thalamus (pol. wzgórze): relays motor and
sensory signals (except smell) to the cerebral
cortex. It is also involved in regulation of
sleep and wakefulness.
Functional brain areas
Hypothalamus (pol. podwzgórze):
maintains the body’s internal balance
(homeostasis). It is responsible for behaviors
such as hunger and thirst, as well as
the maintenance of body temperature, sleep
and circadian rhythm.
It controls autonomic nervous system
It also controls the pituitary gland, which is
the master gland that controls all the other
endocrine glands in the body. Thus, the
hypothalamus connects the endocrine system
with the nervous system.
Functional brain areas
Hippocampus (pol. hipokamp): is responsible
for processing of long term memory and for the
spatial navigation.
It is part of the limbic system, which regulates
emotional responses.
Functional brain areas
Lateral Ventricle (pol. komora boczna) is part
of the ventricular system, which produces
cerebrospinal fluid. The lateral ventricles (left
and right) are the largest of the ventricles.
Functional brain areas
Basal Ganglia (basal nuclei) (pol. zwoje
podstawy (jądra podstawy)) consist of multiple
subcortical structures. They are involved
mainly with voluntary movements.
Caudate (pol. jądro ogoniaste) is involved
with motor processes, procedural learning,
inhibitory control of action.
Functional brain areas
Putamen (pol. skorupa): regulates movements
and influences various types of learning.
Functional brain areas
Amygdala (pol. ciało migdałowate) is
important part of the limbic system. It is
responsible for emotional responses especially
to threatening or dangerous stimuli.
Functional brain areas
White matter (pol. istota biała) is made up of
myelinated axons which connect different brain
regions. White matter gets its color from
myelin, which insulates axons.
Functional brain areas
Gray Matter of Cerebral Cortex (pol. istota szara
kory mózgu) consists mainly of neuronal cell bodies
and non-neuron brain cells.
Cerebral Cortex is evolutionary youngest and most
complex structure of the brain. It is divided into four
different lobes, the frontal, parietal, temporal, and
and occipital, which are each responsible for
processing different types of information.
Occipital lobe (pol. płat potyliczny) is
responsible for processing of visual
information(color, shape, movement, depth).
Temporal lobe (pol. płat skroniowy) is
responsible for processing of auditory
information and visual stimuli (object
recognition). It also contains language area
responsible for speech comprehension.
Parietal lobe (pol. płat ciemieniowy) is
responsible for touch, pain and temperature
perception and for integration of sensory
information among various modalities including
spatial sense and body position.
Frontal lobe (pol. płat czołowy) carries out higher mental
processes such as thinking, decision making, and planning. It
also contains primary motor cortex, which regulates
movements. It also contains language area responsible for
speech generation.
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
Golgi 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
Human brain consists of 100 000 000 000 (1011)
neurons making in total about 1000 000 000 000
000 (1015) connections.
Typical neuron consists of :
1.
Cell body
2.
Dendrites
3.
Axon
4.
Presynaptic terminals
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 human:
About 1011 neurons in the brain
(Each neuron has about 104 connections)
Total length of neurons A = 180 000 km
Earth – Moon distance L = 380 000 km
A/L ~ 1/2
Neuron terminology
Nerve cells which have
long fibers that connect to
other regions of the
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