LECTURES

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LECTURES 4 5 BIOLOGY OF BEHAVIOUR I II
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Biology of Behaviour

• The Brain and Its Components
• Study of the Brain
• Control of Behaviour
• Control of Internal Functions and Automatic
  Behaviour
• Drugs and Behaviour

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The Brain and Its Components

• Structure of the Nervous System
• Cells of the Nervous System
• The Action Potential
• Synapses
• A Simple Neural Circuit

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Structure of the Nervous System

• Central Nervous System (brain and spinal cord)
• Peripheral Nervous System (cranial and spinal
  nerves)

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Structure of the Nervous System
F 4.2
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Cells of the Nervous System
F 4.5
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Basic Nerve Cell Structure Function

• A nerve cell is essentially a bag of chemicals.
• The bag is made of fat whose shape is tailored by
  an interior scaffolding.
• The control of nerve cell function is by the
  genetic material within the cell.
• The surface of the nerve cell contains pores
  which permit the flow of ions through them
• The surface also contains structures that pump
  ions in and out of the cell.
• At rest a nerve cell tends to set a net
  negative charge.

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What is an ion and what do nerve cells do with
them?

• An ion is a charged atom. In biology it always
  takes this form as a particle in dissolved in
  water
• Consider table salt
• Table salt is sodium chloride or the chemical
  shorthand is written as NaCl
• When it is dissolved in water it breaks apart
  to be Na and Cl butheres the important part
• Its not just Na and Cl it is Na and Cl-
• The Na is positively charged and the Cl has a
  negative charge.
• This is also true for other important biological
  salts like potassium chloride and calcium
  chloride

Nerve cells always distribute these ions unevenly
so that there is lots of potassium ion inside the
cell. Whereas on the outside in the space
surrounding nerve cells sodium, calcium and
chloride ions are abundant
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Basic nerve cell facts
Overall this separation of charge creates a
voltage across the cell membrane this is usually
equal to about 70 mV (millivolts)
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The Action Potential
Ion channels and ion transporters regulate the
number of ions inside and outside the axon.
F 4.6
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The Action Potential
http//faculty.washington.edu/chudler/ap.html
F 4.7
1. -70 mV (at rest)
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Synapses
F 4.12
It is the site where the electrical activity of
neuron is passed on to the next. This results in
the release of a chemical substance into the
small space between the two nerves cells This
space is called a synapse This substance
transmits a chemical message from one nerve to
another and it is called a neurotransmitter
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Synapses
F 4.11
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There are basically two kinds of neurotransmitter
action

• Excitatory
• Release tends to increase the likelihood that
  nerve cell receiving the transmitter will
  generate an action potential

• Inhibitory
• Release tends to decrease the likelihood that the
  nerve cell receiving the transmitter will
  generate an action potential

Modulatory neurotransmitters These are
transmitters which either increase or decrease
the efficiency of the excitatory or inhibitory
transmitters
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Synapses
F 4.9
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A Simple Neural Circuit
F 4.13
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A Simple Neural Circuit
F 4.14
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Neurotransmitters I
F 4.12
Glutamate -excitatory
1. Glutamate is released by the arrival of the
action potential in the nerve terminal
3. After activation of the glutamate receptors
the glutamate diffuses away and is mopped up by
the termimal the active process of uptake
2. Opening of the ion channels on the next nerve
cell creates excitation by inducing the flow of
positive charge into the cell
Na
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Why is glutamate important?

• It is the gas pedal of the brain
• It keeps us awake drugs that interfere with the
  glutamate neurotransmission create
  hallucinations, sedation and unconsciousness
• Drugs of use
• Ketamine (anesthetic)
• MK-801 (prevents brain damage because of stroke)
• Drugs of Abuse
• PCP or angel dust

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Neurotransmitters II
F 4.12
GABA inhibitory
1. GABA is released by the arrival of the action
potential in the nerve terminal
3. After activation of the GABA receptors the
GABA diffuses awaya and is mopped up by the
termimals and by helper cells called glia by the
active process of uptake
2. Opening of the ion channels on the next nerve
cell creates inhibitin by inducing the flow of
negatively charged chloride ions in to the the
cell
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Why is GABA important?

• It is the brakes of the brain
• It prevents excess excitation and maintains the
  proper rhythmic activity of the brain drugs that
  block GABA neurotransmission create convulsions
  and death.
• Drugs of use
• Benzodiazepines (Valium, Xanax, librium)
  potentiate GABA action and reduce anxiety, panic
  attack syndrome (anxiolytic action)
• it also induces sleep (sedative action).
• Pentobarbital amd Propofol used to induce
  unconsciousness for surgery (PB also prevents
  brain damage because of stroke and child drowning
  incidents)

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Why is GABA important?(continued)

• Alcoholic beverages have as their primary site of
  action the GABA system
• Muscle relaxants
• Epilepsy treatment
• Drugs of Abuse
• Alcohol
• Valium
• Valium and alcohol ( Jimi Hendrix, and many other
  rock stars)

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Neurotransmitters III
Dopamine modulatory
1. Dopamine is released by the arrival of the
action potential in the nerve terminal
3. After activation of the dopamine is also
mopped up by the termimal the active process of
uptake
2. Activation of dopamine receptors creates a
secondary chemical signal within the nerve cell
which modifies quality of the excitation and
inhibition that the cells receives.
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What is dopamine and why is it important?

• Dopamine is another neurotransmitter which is
  very important for modulating the activity of the
  brain
• Dopamine activity is implicated in the following
  diseases
• Parkinsons disease
• Schizophrenia
• Addiction
• Depression
• Attention deficit syndrome
• Obsessive compulsive disorder

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Dopamine activity is compartmentalized

• Two Broad classifications of dopamine action
• Affective behaviours
• Attention
• Reward
• Addiction
• Movement behaviours
• Initiating voluntary movement
• These two types of behaviour are controlled by
  different parts of the brain.

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Parkinsons Disease

• Manifested by
• Difficulty in initiating movements
• Difficulty in a executing smooth movement
• Loss of dopamine containing cells that are
  located in brain region known as the substancia
  nigra SN
• It has occurred in younger people who took the
  drug methamphetamine contaminated with a by
  product created through poor quality control
  MPTP, it is specifically toxic to SN.
• Substancia nigra cells have axons that normally
  release dopamine and these axons project to
  another part of the brain called the striatum
  this part of the brain which controls voluntary
  movement depends on the modulatory effects of
  dopamine and so movement is altered.
• Treatment give back dopamine artificially in
  the form of a pill (actually it is drug,
  Levodopa, that is converted to dopamine)

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Schizophrenia

• Means split brainbut the disease rarely
  manifests itself a true or mulitple personality
  (no matter what Jim Carey says)
• 1.1 of the population age 18 and older in a
  given year have schizophrenia
• Usually characterised by paranoid delusions (Type
  1)
• Delusions (false beliefs)
• Hallucinations (perceiving the presence of
  something not really there)
• Disorganized speech
• Irrational or catatonic behavior, such as stupor,
  rigidity, or floppiness of limbs.
• OR.
• Absence of thought or affect (Type II)
• Negative symptoms, such as inaction, silence, or
  loss of will
• Treated by neuroleptics drugs which block the
  action of dopamine in the cortex ie the disease
  appears to be caused by excess dopamine action
• clozepine is an example of widely used
  antipsychotic for the treatment of schizophrenia

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Schizophrenia
Bad Day
Good Day
Vincent Van Gogh
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Drugs and Behaviour

• Effects of Drugs on Synaptic Transmission a few
  examples

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Effects of Drugs on Synaptic Transmission
F 4.34
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Effects of Drugs on Synaptic Transmission
F 4.35
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Effects of Drugs on Synaptic Transmission
F 4.36
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Addiction and Dopamine

• What is drug addiction?
• Biological addiction refers to a state of
  physical dependence on a drug whereby
  discontinuing drug intake produces a withdrawal
  syndrome consisting of various somatic
  disturbances.
• A broader definition Addiction is a behavioral
  syndrome where drug procurement and use seem to
  dominate the individuals motivation and where
  the normal constraints on behavior are largely
  ineffective.
• Sometimes this broader definition is described as
  a "psychological" addiction (thus distinguishing
  it from physical dependence archaically termed
  "physical" addiction),
• the condition commonly referred to as addiction
  is the ability of the drug to dominate the
  individuals behavior, regardless of whether
  physical dependence is also produced by the drug.
  

www.addictionscience.net/ASNbiological.htm
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How does addiction happen? (biologically and
psychologically)

• What causes drug addiction?
• Many factors influence a persons initial drug
  use. Personality characteristics, peer pressure,
  and psychological stress can all contribute to
  the early stage of drug abuse.
• These factors are less important as drug use
  continues and the person repeatedly experiences
  the potent pharmacological effects of the drug.
• This chemical action, which stimulates certain
  brain systems, produces the addiction, while
  other psychological and social factors become
  less and less important in influencing the
  individuals behavior.
• When the pharmacological action of a drug
  dominates the individuals behavior and the
  normal psychological and social control of
  behavior is no longer effective, the addiction is
  fully developed.

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How is drug addiction related to "normal"
behavior?

• Specialized brain reward systems have evolved to
  ensure survival of the species. Directing
  behaviour that promotes survival of the
  individual and of the species. Fat sex are
  good examples.
• Activation of brain reward systems produces
  changes in affect ranging from slight mood
  elevation to intense pleasure and euphoria, and
  these psychological states help direct behavior
  toward natural rewards.
• Some chemicals activate brain reward systems
  directly, bypassing the sensory receptors
  mediating natural rewards. Caffeine, alcohol,
  nicotine all activate brain reward mechanisms
  directly.
• Moderate use of these substances has gained
  widespread acceptance over the centuries,
  although their use has been periodically
  prohibited
• However other drugs much more potently activate
  brain reward systems. But the activation is so
  much more intense it causes the individual to
  crave the drug and to focus their activities
  around taking the drug.
• The ability of addictive drugs to strongly
  activate brain reward mechanisms and their
  ability to chemically alter the normal
  functioning of these systems can produce an
  addiction.

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The system that is usually associated with reward
behaviour is the mesolimbic dopamine system

• Cells in the mesolimbic dopamine system are
  spontaneously active -- action potentials are
  constantly generated at a slow rate. This
  releases small amounts of dopamine into the
  synaptic cleft. The levels of dopamine produced
  when the cells are active at this low rate may be
  responsible for maintaining normal affective tone
  and mood. Some scientists speculate that some
  forms of clinical depression may result from
  unusually low dopamine levels.
• Cocaine inhibits the reuptake of dopamine. This
  increases the availability of dopamine in the
  synapse and increases dopamine's action on the
  postsynaptic neurons. The enhanced dopamine
  activity produces mood elevation and euphoria.
  Cocaine's effect is usually quite short,
  prompting the user to repeatedly administer
  cocaine to re-experience its intense subjective
  effects.

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The system that is usually associated with reward
behaviour is the mesolimbic dopamine system

• Heroin increases the neuronal firing rate of
  dopamine cells. The increased number of action
  potentials produce an increase in dopamine
  release. Thus the heroin user experiences the
  enhanced dopamine activity as mood elevation and
  euphoria.
• Neuroadpative Effects (Addictive)
• repeated use of psychomotor stimulants like
  cocaine and opiates like heroin produces changes
  in the mesolimbic dopamine system causing the
  depletion of dopamine from this system.
• These dopamine depletions may cause normal
  rewards to lose their motivational significance
  (i.e., produce motivational toxicity).
• Also, the mesolimbic dopamine system becomes even
  more sensitive to pharmacological activation by
  psychomotor stimulants and by opiates (i.e.,
  sensitization develops).
• These neuroadpative changes are probably critical
  for producing an addiction. Substances that
  activate the mesolimbic dopamine system without
  producing these neuroadaptive effects are
  probably not truly addictive.

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Study of the Brain

• Research Methods of Physiological Psychology
• Anatomical
• Physiological
• Biochemical
• Pharmacological
• Genetic
• Behavioural

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Research Methods of Physiological Psychology
How do we know that dopamine involved? Hypothesis
That electrical stimulation of the mesolimbic
dopamine area will cause the rat to addicted to
the elctrical stimulation Implant electrodes in
brain of rat in mesolimbic area and use them to
stimulate the reward area So by training the
rat to perform a task then stimulating this area
this will re-inforce the performance
F 4.15
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Research Methods of Physiological Psychology
F 4.16
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Research Methods of Physiological Psychology
The rat does learn that pressing the bar causes a
reward feeling to be felt. In fact the rat will
repeated press the bar once it becomes addicted
to performing the task
F 4.17
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Control of Behaviour

• Organization of the Cerebral Cortex
• Lateralization of Function

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Organization of the Cerebral Cortex
F 4.23
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Organization of the Cerebral Cortex
F 4.24
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Organization of the Cerebral Cortex
F 4.25
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Organization of the Cerebral Cortex
F 4.26
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Lateralization of Function
F 4.28
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Control of Internal Functions and Automatic
Behaviour

• The Brain Stem
• The Cerebellum
• Structures within the Cerebral Hemispheres

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The Brain Stem and Cerebellum
F 4.30
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Structures within the Hemispheres
F 4.31
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Structures within the Hemispheres
F 4.33