Download PSYB1 Revision sheet Biopsychology JM09

Biopsychology: Revision Sheet (December 09)
Assessment: External exam: PSYB1: 13th January 2010, Wednesday 9am
Physiological psychology
Basic understanding of the structure and function of neurons
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No two neurons are the same
But they all do have the same basic structure.
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Axon – can be up over a metre long (down spine) or a
few millimetres (in brain)
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Myelin sheath – insulates the axon, increases speed of
impulses, (give nerves and the brain the white
appearance).
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Action potential – messages move along the neuron in
the form of an electrical impulse known as an action
potential.
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Dendrites – the branched structures at the end of the
axon. Branched so they can connect with many other
neurons
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Types of neuron
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Motor neuron - To carry impulses from the central nervous system to the organs and muscles.
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Sensory neuron - To transport impulses from the peripheral nervous system to the brain and spinal cord.
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Relay neuron To receive impulses from sensory neurons and transfer them to motor neurons.
One difference in function between a motor neuron and a sensory neuron.
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The function of a motor neuron is to carry information from the central nervous system to the muscles/glands/effectors, whereas
the function of a sensory neuron is to carry information from the sense organs to the central nervous system.
Synaptic Transmission
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Synapse: The junction between two neurons
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Neurons do not actually touch each other, but rather there is a gap called a synapse through which the electrical impulse
“jumps”
Synaptic transmission: The transfer of an impulse from one neuron to another.
Neurotransmitter – a chemical involved in synaptic transmission e.g. serotonin, dopamine, endorphin
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Neurotransmitters can either increase or decrease the firing rate of the next neuron.
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Neurotransmitters are known to have an effect on behaviour and mental processes
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E.g. endorphins – reduce feelings of pain
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Dopamine – involved in emotional arousal, and movement
Divisions of the nervous system
Autonomic nervous system (ANS)
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Operates largely outside the conscious
control of a person.
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It is part of the peripheral nervous
system.
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“Autonomic” because it is mostly
automatic.
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In some cases people can learn to
control it.
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Linked to the endocrine system
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Sympathetic – prepares body for
action
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Parasympathetic – reduces the
activities of the body.
Localisation of function
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Localisation of function suggests that there are specific parts of the cerebral cortex which have specific functions
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Motor area – involved in producing and regulating voluntary movements.
Somoatosensory area – receives information about touch, temperature and brain.
Broca area – speech production
Wernicke area – understanding of written and spoken language
Visual area is responsible for converting electrical signals from the eye into visual
images (sight)
Methods used to identify areas of cortical specialisation
Keywords:

Temporal resolution refers to the precision of a measurement with respect to time.
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Spatial resolution: The ability to sharply and clearly define the extent or shape of features within an image.
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EEGs have good temporal resolution as they take readings every millisecond, but poor spatial resolution as they can only tell roughly
where in the brain the electrical signals are originating from.
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MRI, PET, & CAT scans have good spatial resolution but poor temporal resolution
Method
MRI
Description & What it measures
Evaluation
Areas of the brain which are most
active need more blood. Blood
contains haemoglobin, which
contains iron, which is magnetic.
Magnetic resonance will change as
blood flow changes.
Positive
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No harmful effects on patient or operator.
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scans are non-invasive and therefore raise fewer ethical issues, eg
less harm.
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Good spatial resolution.
Negative
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Poor temporal resolution.
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Can not usually be used on people with pacemakers, or metal
implants / metal fragments in the body. Can be uncomfortable due
to loud noise, vibrations, and claustrophobic nature of the device people with even mild claustrophobia are often unable to tolerate an
MRI scan.
Positive
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Good spatial resolution
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Non-invasive way of studying the brain.
Negative
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Poor temporal resolution.
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Need permission from ethics committees to inject radioactive
material, although dose is very small.
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Expensive and difficult to use.
Positive
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Good temporal resolution. Can record changes on a millisecond
level. Very few other techniques have such a high temporal
resolution.
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Non-invasive.
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EEG measures are less harmful than surgical procedures,
Negative
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Poor spatial resolution. Limited anatomical specificity – can only
detect when groups of neurons are firing, and not precisely where.
Positive
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Good spatial resolution
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Non-invasive way of studying the brain.
Measures blood flow in the brain, by
magnetic resonance.
PET
Radioactive glucose is injected into
the participant. The parts of the
brain which are most active, use
more glucose, and show on the
scan.
EEG
Electrodes are placed on the scalp.
The brain is believed to work
through it’s electrical activity.
EEGs provide natural
measurements of brain activity,
Measures electrical activity in the
cerebral cortex.
CAT scan
Measures tissue density
Lots of x-rays
Post mortem
examination
Neuros-urgery
Examination of brain after death
Involves cutting, removing or
damaging part of the brain and then
observing the affects on behaviour.
Often used with animals.
Electrical stimulation of
brain areas
Uses electricity to stimulated
specific brain areas
Negative
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Positive
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Poor temporal resolution.
Dangerous x-ray radiation
Useful for looking at the brain closely and in detail.
Post-mortem studies provide understanding of rare disorders;
Useful for studying the brains of people with specific psychological
problems. e.g. schizophrenia, speech problems
Negative
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Participant needs to die before the brain can be examined.
Positive
Negative
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Often used with animals – and this research may not be possible to
generalise to humans.
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Methodological – brain plasticity – removing one part of the brain
may only show the performance of the rest of the brain, not the
missing part;
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lack of precision - the exact extent of damage to the brain may be
difficult to assess; accuracy of neurosurgery;
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Ethical – invasive exposure of the brain with neurosurgery,
Positive
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Useful for determining localisation of function before brain surgery.
Negative
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It is invasive. Involves removing skull, and is therefore dangerous.
Divisions of the autonomic nervous system
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sympathetic branch: prepares the body for action in threatening situations;
parasympathetic branch. supports and restores normal body activity by conserving and storing energy.
It also slows the activities of the body that have been increased by the sympathetic nervous system.
Slows heart rate / increases digestion / constricts pupils, etc.
Adrenal glands and adrenaline
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The adrenal glands are stimulated to release adrenaline. This prepares the body for action in a stressful situation.
Fight or flight response
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In an emergency situation, the body is prepared for the possibility of defending or attacking (fight), or running away to safety (flight).
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eg increased heart rate, role of the ANS, accelerated heart rate, curtailing of digestion, increased respiration, increase in
perspiration, release of glucose from the liver, pupil dilation, decrease in salivation, slowing of peristalsis, adrenaline release.
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e.g. If suddenly confronted by a vicious dog, you either defend yourself (fight) or run away (flight).
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An early evolutionary adaptation that is useful in dealing with physical threats
Helps us deal with short-term problems that can be solved by fighting or running
(Unfortunately, many of the threats we face in our society do not fall into these categories – hence can lead to stress related problems)
Genetics
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Genotype: A person’s genetic make-up, as represented by the genes on the 23 pairs of human chromosomes
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Phenotype: A person’s actual/observable characteristics that are determined by genetics and the environment. e.g. physical
appearance, behavioural characteristics, personality.
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Genotype never changes; phenotype can change over time.
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Use an example to illustrate the difference between them.
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In relation to intelligence they may explain that an individual might have an intellectual potential (genotype) but they require
environmental stimulus such as education for this to develop.
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PKU is an example of a disorder caused by a defective gene resulting in severe learning difficulties. However, if identified
early, and treated with a special diet, individuals show normal levels of intelligence.
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Other example e.g. schizophrenia.
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Monozygotic (MZ) twins: Identical twins. Twins that share exactly the same genetic make-up because they develop from one fertilised
egg that divides into two separate embryos. MZ twins have exactly the same genotype.
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Dizygotic (DZ) twins: Non-identical twins. Develop from two separate eggs that are fertilised by different sperm. DZ twins have 50% of
their genes the same. (also referred to as fraternal twins)
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Concordance: The percentage likelihood that if one individual in a pair has a trait the other individual also has that trait.
Twin studies
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Look at concordance rate in MZ twins for a particular characteristic. This gives an indication as to how much the characteristic is due to
genetics.
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A characteristic that is 100% due to genetics (e.g. blood type) would have a 100% concordance rate in MZ twins.
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Also identical twins raised together, and compare with fraternal twins.
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Compare concordance rates in MZ twins with concordance rate in DZ twins for a particular characteristic.
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If the characteristic has a higher concordance rate in MZ twins it indicates a genetic basis.
Family studies
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Investigate how much a characteristic runs in families
Adoption Studies
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Compare a trait or characteristic of an adopted child with their biological relative.
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This controls for environmental influences
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If a trait or characteristic is heritable, then children should show greater similarity to their biological parents than adopted parents. If
concordance/ correlation/similarity for adopted children is higher with natural parents than adopted parents, then the trait is biological.
Gene Sequencing
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Use DNA analysis to investigate whether certain genes are associated with certain traits