Armin Falk and Bernd Weber

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Neuroeconomics Part II Methods

• Armin Falk and Bernd Weber
• Universität Bonn, SS 08

www.neuroeconomics-bonn.org
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Books
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Overview
Macroanatomy of the brain Biology of Neurons
(Microanatomy) - neurons and glial cells -
electrochemical basis of nerve function -
chemical basis of nerve communication Functional
Neuroanatomy (systems of the nervous system) -
Somatosensory System - Motor System - Visual
System - Limbic System - Reward System
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Neuroanatomy
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Division of the nervous system

• Central Nervous System
• Peripheral Nervous System

Brain
Spinal Cord
Cranial Nerves
Spinal Nerves
Peripheral Ganglia
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Central Nervous System (CNS)

• 7 Main Parts of the CNS
• Spinal Cord
• Medulla oblongata
• Pons
• Cerebellum
• Midbrain
• Diencephalon
• Cerebrum

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Directions in the nervous system - Axes
Orientation Axes in the brain Rostral-Caudal
(front-back) ? anterior-posterior Dorsal-Ventr
al (up down) Lateral-Medial (sideways mid)
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Directions in the nervous system - Planes
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Development of the CNS
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Maturation of the CNS
Brain weight at birth 400 g At 2 years 1000
g Adult 1500 g Maturation is mostly based on
differentiation of nerve-cell connectivty
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The lobes of the brain

• Four lobes of the brain
• Frontal lobe
• Parietal lobe
• Occipital lobe
• Temporal lobe

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Internal Structures Subcortical

• Some structures cannot be seen from the surface
  of the brain, i.e.
• subcortial structures, e.g.
• Basal ganglia
• insular cortex
• medial temporal lobe
• ventricles

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From macro- to microanatomy
Difference of white- and grey matter Grey
matter nerve cell bodies White matter nerve
fibres
Coronal section of a macaque brain
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Histological organization of grey matter
The cortex is arranged out of 6 histological
layers which have distinct processing and
input-/output functions
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Brodmann areas histological division of the
brain
Based on the differences in layer organization,
the brain has been mapped into 52 areas by
Korbinian Brodmann 1909
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Function of different layers
Neurons in different layers have distinct
projection characteristics
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Interneurons modulate Projection neurons
Interneurons do not project to other areas of the
brain, but modulate the activity of primary
projection neurons either inhibitory or
excitatory.
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Microanatomy
The brain consists of about 100 billion cells.
Nerve cells (neurons)
Glia (glial cells)
Control of environment of neurons
processing units
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Nerve cells (neurons)
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Sketch of a neuron
Nucleus
Axons
Dendrites
Dendrites
Myelin

• Dendrites -- Input
• Cell body (soma) -- Integration
• Axon -- Output

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Structure of neurons - Dendrites
At dendrites, the neurons recieve input via axons
of other neurons at synapses
dendritic spine
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Structure of neurons - Soma
In the soma of the cells, the cell nucleus is
located (containing the DNA, i.e. genetic code)
the synthesis of the proteins (within ribosomes
and endoplasmatic reticulum) as well as energy
production (mitochondria) are performed.
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Structure of neurons - Axon
The axon transmits the information electrically
from the soma to the synapses it is surrounded
by myelin that insulate the axon, provided by
oligodendrocytes (glial cells)
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Sketch of a neuron
Nucleus
Axons
Dendrites
Dendrites
Myelin

• Dendrites -- Input
• Cell body (soma) Integration protein
  production, genes, energy production
• Axon -- Output

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Electrical properties of neurons
extracellular
intracellular
The cell membrane isolates the intracellular from
extracellular space
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Electrical properties of neurons
The membrane potential
extracellular
difference of -70 mV
intracellular
In the resting state, the intracellular space
contains more negative ions than the
extracellular space
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Ion channels connect the intra- and extracellular
space
Opening of ion channels lead to a flux of ions
through the membrane and to a change of the
membrane potential
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Different types of ion channels
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The action potential
The action potential is generated by ion flux
through voltage gated channels
All or nothing principle!!
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Propagation of the action potential
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Synapse Communication between neurons
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Synapse Communication between neurons
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Synapse Communication between neurons
Presynaptic vesicles with neurotransmitter
Released transmitter
Transmitter binds to receptor
Transmitter-Resorption from synaptic cleft
Na
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Excitatory and Inhibitory Synapses
Excitatory postsynaptic potential (EPSP)
Inhibitory postsynaptic potential (EPSP)
Depending on the neurotransmitter and the
receptor, the postsynaptic potential can be
excitatory or inhibitory
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Important Neurotransmitters

• Dopamine
• Epinephrine
• Norepinephrine
• Acetylcholine
• Serotonine
• Glycine
• GABA
• Glutamate

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Two forms of integration of information
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EPSC at dendrite can lead to action potential
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Effect of inhibition on excitation
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Glial cells
oligodendrocytes
astrocytes
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Astrocytes
Astrocytes connect the extraneuronal space with
the blood vessels
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Oligodendrocytes
Oligodendrocytes sheat the axons of the neurons
to increase conductance of action potential
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Summary neuronal communication

• intracellular electrical transmission of
  information (action potential)
• neurons communicate via biochemical transmission
  (neurotransmitters and receptors)
• integration of information in neurons by means
  of spatial and temporal summation

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Plasticity of the brain building of synapses