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psy251-weeks-1-to-11-summary-psychology-biological-bases-of-behaviour

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PSY251 - Weeks 1 to 11 - Summary Psychology: Biological
Bases of Behaviour
Psychology: Biological Bases of Behaviour (Murdoch University)
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PRACTICE TEST
Limbic System:
- Hippocampus (memories)
- Amygdala (emotions)
- Basal Ganglia (voluntary movements)
Prefrontal cortex: impulse control/making good decisions.
The view of the brain from above is called the dorsal view (dolphin fin/d before v).
The view of the brain from the bottom is called the ventral view (v below d).
Interruption of the production of RNA would directly affect protein synthesis.
The peripheral division of the nervous system is composed of the autonomic and somatic
nervous system.
The hindbrain consists of the medulla, pons and cerebellum.
The thalamus can be thought of as a relay centre.
Cortical blindness may result from the destruction of the occipital cortex.
The tree-like branches of a neuron that receives information from other neurons are called
dendrites.
A receptor can directly open a channel exerting an inotropic effect or it can produce a
slower but longer metabotropic effects.
EPSPs increase the spontaneous firing rate of neurons.
Vesicles are located in the presynaptic terminals.
After a series of electric shocks, a person becomes over-responsive to lights and noises.
This exemplifies sensitization.
The ability of the brain to change its anatomy over time within limits, is known as
plasticity.
Sensations from phantom limbs are a result of brain reorganisation.
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What is different about rats raised in an enriched environment versus rats raised in an
impoverished environment? Improved learning performance.
We can gain an understanding of neuroplasticity in the human brain through:
- fMRI
- Transcranial direct current stimulation
- Transcranial magnetic stimulation
PET and fMRI tell us about the activity of the brain.
One function of the thalamus is to relay sensory information to the cerebral cortex.
Modern methods have demonstrated that phantom limbs develop only if the relevant
portion of the somatosensory cortex reorganises and become responsible to alternative
inputs.
The ‘spontaneous firing rate’ of a neuron refers to its rate of producing action potentials
even when it is not stimulated.
Evolutionary vs functional explanation of behaviour: Evolutionary behaviour
reconstructs the evolutionary history of a structure or behaviour. Functional behaviour
describes why a behaviour evolved as it did.
PET scan: uses an injection of a radioactive substance that as it decays, produces gamma
rays that are detected outside of the head. Greater radioactivity in a particular area indicates
greater blood flow to that region.
fMRI: The presence of haemoglobin with oxygen acts differently in a magnetic field than
haemoglobin without oxygen. Because active areas of the brain use more oxygen, these
areas are detected by the magnetic machine and differences recorded via photos 1 to 4
seconds apart.
MRI and CT assess brain anatomy only.
All-or-none law of action potential: once a neuron reaches the threshold of activation, the
action potential is conducted all of the way down the axon without loss of intensity. Also,
the magnitude of the action potential is roughly the same very time and is independent of
the insanity of the stimulus that initiated it.
Functional neuroplasticity involves changes in synaptic activity/strength; a strengthening
of long-term potentional and a weakening of long-term depression.
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WEEK ONE – BOOK NOTES
Biological psychology is the study of the physiological evolutionary and developmental
mechanism of behaviour and experience.
Dorsal view – view of human brain from the top.
Ventral view – view of human brain from the bottom.
Two kinds of cells (at the microscopic level):
1. Neurons
2. Glia
Neurons convey messages to:
1. One another
2. Muscles
3. Glands
The glia has many functions but does not convey information over great distances.
The glia cells surround neurons and provide support for and insulation between
them. Glia cells are the most abundant cell types in the central nervous system.
Biological explanation of behaviour fall into four categories:
1. Physiological
2. Ontogenetic
3. Evolutionary
4. Functional
Physiological explanation: relates a behaviour to the activity of the brain and other organs.
It deals with the machinery of the body.
Ontogenetic explanation: describes how a structure or behaviour develops, including the
influence of genes, nutrition, experiences, and their interactions.
Evolutionary explanation: reconstructs the evolutionary history of behaviour.
Functional explanation: describes why a structure or behaviour evolves as it did.
A strand of DNA serves as a template for the synthesis of ribonucleic acid (RNA)
molecules, single strand molecules.
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Four types of questions:
1. Physiological: How foes the behaviour relate o the physiology of the brain and the other
organs?
2. Ontogenetic: How does it develop within the individual?
3. Evolutionary: How did the capacity for the behaviour evolve?
4. Functional: Why did the capacity for this behaviour evolve?
Homozygous: identical pair of genes on the two chromosomes for that gene.
Heterozygous: unmatched paid of genes for that gene chromosome.
Genes are dominated, recessive or intermediate.
Dominant gene: shows a stronger effect in either the homozygous or heterozygous
condition.
Recessive gene: shows its effect only in the homozygous condition.
X and Y are sex-linked genes on the sex chromosomes. All other chromosomes are
autosomal chromosomes.
Genes change by mutation, duplication or deletion.
Evolution occurs as:
- Offspring generally resemble parents for genetic reasons
- Mutations, recombinations and microduplications of genes introduce new heritable
variations that help or harm an individual’s chance of surviving or reproducing
- Certain individuals successfully reproduce more than others do, thus passing on their
genes to the next generation.
The nervous system is divided into two subunits:
1. The central nervous system (CNS)
2. The peripheral nervous system (PNS)
The central nervous system includes the brain and spinal cord.
The PNS is made up of the cranial nerves that enter and leave the underside of the brain,
and the spinal cord nerves that connect to the sides of the spinal cord at each vertebra.
A neuron is a single nerve cell.
A nerve is a bundle of axons running together (like a multi-wire cable).
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Term nerve is only used in PNS  CNS use the term tracts.
A group of cell bodies is called:
- CNS: a nucleus
- PNS: a ganglion
Forebrain includes:
- Cerebral hemispheres
- Thalamus
- Hypothalamus
- Cortex
Longitudinal fissures: separates the two cerebral hemispheres.
Gyrus: ridges in the brain.
Sulcus: groove or space between two gyri if it is small (fissure if it is large).
Cortex: outer layer which is made up of the cell bodies of neurons. Referred to as gray
matter as cells are not myelinated. The cortex is only 1.5-4mm thick.
Axons: axons come together in the central core of each gyris. White appearance due to
myelination.
Myelin: A mixture of proteins and phospholipids forming a whitish insulating sheath
around many nerve fibres, which increases the speed at which impulses are conducted.
The four lobes of the hemisphere are named after the bone of the skull above it.
Four lobes:
1. Frontal
2. Occipital
3. Parietal
4. Temporal
The PNS consists of the somatic and autonomic NS:
- The somatic NS consists of the sensory nerves and the nerves controlling the skeletal
muscles.
- The autonomic NS consists of the sympathetic and parasympathetic branch.
The parasympathetic branch conserve and renew energy.
The sympathetic branch prepares the body for action.
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WEEK TWO – BOOK NOTES
Brain wiring is mainly contralateral: RH processes information from the LVF, LH
processes information from RVF.
Both hemispheres dictate the movement of the upper arms.
The two hemispheres are connected by neuronal bridges called commissure. The largest of
these is called corpus callomus.
Phineas Gage’s behaviour changed due to the injury. His intact hemisphere reorganised and
took on some roles of the damaged hemispheres.
WEEK THREE – BOOK NOTES
Neurons receive information and transmit it to other cells.
Membrane: the surface of a cell. It is composed of two layers of fat molecules that are free
to flow around.
Most chemicals cannot cross the membrane, but specific protein channels permit a
controlled flow of water, oxygen, sodium, potassium, chlorine and calcium.
Mitochondria: structure that performs metabolic activities, providing the energy that the
cell requires for all other activities.
Ribosomes are the sides at which the cells synthesises new protein.
Larger neurons have:
- Dendrites
- A soma/cell body
- An axon
- A presynaptic terminal
Motor neuron: has its soma in the spinal cord. It receive excitation form other neurons
through tis dendrites and conducts impulses along its axon to a muscle.
A sensory neuron is specialised at one end to be highly sensitive to a particular type of
stimulation.
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Dendrites: branding fibres. Their surface is lined with specialised synaptic receptors at
which the dendrite receives information from other neurons.
A soma (cell body): contains the nucleus, ribosomes and mitochondria. The metabolic
work a neuron occurs here.
An axon: the neuron’s information sender, conveying an impulse towards other neurons or
an organ or a muscle.
A neuron has only one axon, but multiple dendrites.
Afferent axon: bring information into a structure.
Effecter axon: carries information away from a structure.
If a cell’s dendrites and axon are entirely contained within a single structure, the cell is an
intrinsic neuron.
The brain has several types of glia with different functions. The star-shaped astrocytes wrap
around the presynaptic terminals of a group of functionally related axon. By taking up ions
released by axons and then releasing them back to axons, an astrocyte helps synchronise the
activity of axons.
Astrocytes also remove waste material created when neurons die and control the amount of
blood flow to each brain area.
A graded depolarisation is known as an excitary postsynaptic potential (EPSP). It results
from a flow of sodium ions into the neuron. If an EPSP does not cause the cell to reach its
threshold, the depolarisation decays quickly.
Spontaneous firing rate: a periodic production of action potentials even without synaptic
input.
Synapse: point of communication between two neurons.
Inhibition: an active “brake” that suppresses excitation.
An inhibitory graded potential (hyperpolarising) is an IPSP.
An EPSP occurs when gates open to allow sodium to enter the neurons membrane.
An IPSP occurs when the gates open to allow potassium to leave or chlorine to enter.
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The chemical events behind the action potential make sense if you remember these
principles:
1. At the start, sodium ions are mostly outside the neuron and potassium ions are mostly
inside.
2. When the membrane is depolarised, sodium and potassium channels in the membrane
open.
3. At the peak of the action potential, he sodium channels close
The channels regulating sodium and potassium are voltage-gated channels. That is, their
permeability depends on the voltage difference across the membrane.
Immediately after an action potential, the cell is in a refractory period during which it resists
the production of further action potentials. In the first part of this period, the absolute
refractory period, the membrane cannot produce an action potential, regardless of the
stimulation. During the second part, the relative refractory period, a stronger than usual
stimulus is necessary to initiate an action potential. The refractory period has two
mechanisms: the sodium channels are closed, and the potassium is flowing out of the cell at
a faster than usual rate.
The term propagation of the action potential describes the transmission of an action
potential down an axon.
Action potential:
- When an area of the axon membrane reaches its threshold of excitation, sodium channels
and potassium channels open
- At first, the opening of potassium channels produces little effect
- Opening sodium channels lets sodium ions rush into the axon
- Positive charges flow down the axon and opens voltage-gated sodium channels at the next
point
- At the peak of the action potential, the sodium gates snap shut. They remain closed for the
next millisecond or so, despite the depolarisation of the membrane.
- Because the membrane is depolarised, voltage-gated potassium channels are open.
- Potassium ions flow out of the axons, returning the membrane towards its original
depolarisation.
- A few milliseconds later, the voltage-dependent potassium channels close
At a synapse, a neuron releases chemicals that affect another neuron. Those chemicals are
known as neurotransmitters (mainly amino acids, monoamines, acetylcholine,
neuropeptides, purines, gases and ides).
Presynaptic terminals store high concentrations of neurotransmitter molecules in vesicles.
Vesicles are tiny, nearly spherical packets.
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A neurogliaform cell – releases huge amounts of GABA all at once, forming a “cloud” that
spreads to a large number of neurons in the area, producing widespread inhibition.
Hormone – chemical that is secreted by cells in one part of the body and conveyed by the
blood to influence other cells.
Protein and peptide hormones attach to membrane receptors, where they activate a second
messenger within a cell.
The pituitary gland consists of an anterior and posterior pituitary.
Neurons in the hypothalamus synthesis the hormones oxytocins and vasopressin, which
migate down axons to the posterior pituitary.
The hypothalamus secretes releasing hormones, which flow through the blood to the
anterior pituitary.
Reuptake: the presynaptic neuron takes up most of the release neurotransmitter molecules
intact and reuses them. This occurs through special membrane proteins called transports.
Autoreceptors: receptors that respond to the released transmitted by inhibiting further
synthesis and release. That is, they provide negative feedback.
Gap junction: At an electrical synapse, the membrane of one neurone comes into direct
contact with the membrane of another.
Neuropeptides are important for hunger, thirst, and other slow, long-term processes.
WEEK FOUR – BOOK NOTES
Instinct – A stereotyped pattern of behaviour elicited by particular environmental stimuli.
Learning is either associated of non-associative.
Associative learning occurs when an organism form a connection between two features of
its environment.
Non-associative learning involves changes in the magnitude of responses to stimuli rather
than formation of connections between specific elements or events.
Sensitisation: occurs when repeated exposure to a strong stimulus increases responses to
other environmental stimuli.
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Interpositus nucleus – a cerebellar nucleus thought to be essential to classical conditioning
in vertebrates.
In the cerebellar cortex, large Purkjne cells receive inputs known as climbing fibres from
neurons, located in the interior olive in the medulla. The Purkjne cells also receive input
from parallel fibres. These fibres are known as granule cells.
Granule cells receive input from mossy fibres, which originate from the neurons in the
pons.
Long-term depression: a type of synaptic plasticity in which postsynaptic potentials in
targets are reduced.
Delayed conditioning: a type of classical conditioning in which CS onset precedes and
overlaps UCS onset.
Trace conditioning: a type of classical conditioning in which the CS an UCS do not
overlap in time.
Sensory memory: an initial stage in memory formation in which large amounts of data can
be held for very short periods.
Short-term memory: an intermediately memory store in which limited amounts of data can
be held for a limited amount of time; without further processing, such information is
permanently lost.
Long-term memory – a memory store in which apparently unlimited amounts of data can
be held for an unlimited amount of time.
Semantic memory contains basic knowledge of facts and language.
Episodic memory relates to your own personal experience.
Procedural memory store information about motor skills and procedures.
Semantic and episodic memories are grouped together as declarative.
Anterograde amnesia – memory loss for information processed following damage to the
brain.
Engram – a physical memory trace in the brain.
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Delayed non-matching to sample (DNMS) task – a standard test of memory in which the
subject must identify the novel member of a stimulus pair following a delay.
Structures typically damaged by medial temporal lobe lesions include the amygdala, the
hippocampus, and the surrounding areas of the cortex, known as the parahippocampal
cortex and the rhinal cortex.
Entorhinal cortex – a subdivision of the rhinal cortex, which lies ventral to the
hippocampus.
Perirhinal cortex – a substructure of the rhinal cortex.
Fornix – a pathway carrying information from the hippocampus to the hypothalamus.
Ammon’s horn – one of two major layers of neurons found in the hippocampus.
Dentate gyrus – one of two major layers of neurons found in the hippocampus.
Perforant pathway – a pathway made up of axons originating in the rhinal cortex that form
synapses in the dentate gyrus of the hippocampus.
Mossy fibre - an axon from the dentate gyrus that synapses on cells found in CA3 of
Ammon’s horn.
Schaffer collateral pathway – A pathway connecting CA3 to CA1 in Ammon’s horn of the
hippocampus.
Long-term potentiation (LTP) – A type of synaptic plasticity in which the application of a
rapid series of electrical shocks to an input pathway increases the postsynaptic potentials
recorded in target neurons.
Associativity – A condition believed necessary for learning in which the pre- and
postsynaptic neurons are nearly simultaneously active.
Cooperativity – A condition for the formation of LTP in which several synapses onto the
target postsynaptic nervous must be simultaneously active.
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WEEK SIX – BOOK NOTES
A myelin stain allows you to follow pathways carrying information from one part of the
brain to another by staining the insulating material that covers may nerve fibres.
CT (computerised tomography) scans allow for the construction of highly detailed threedimensional images.
PET (positron emission tomography) scan brain studies combine radioactive tracers with
a wide variety of molecules. Each gamma ray resulting from the breakdown of the tracer is
recorder by detectors and fed to a computer, by which the data are restricted into images.
MRI (magnetic resonance imaging) uses powerful magnets to align hydrogen atoms
within a magnetic field. Next, radio frequency (RF) pulses are directed at the part of the
body to be imaged, producing “resonance” or spinning, of the hydrogen atoms. When the
RF pulses cease, the hydrogen atoms return to their natural alignment within the magnetic
field. As the atoms “relax”, each becomes a miniature radio transmitter, emitting a
characterise pulse that is detected by the scanned. To construct the image, each small area of
tissue is designated a voxel.
fMRI (Functional MRI) is used to assess brain activity. It uses a series of MRI images
taken 1 to 4 seconds apart in order to assess the activity of the brain.
EEG (electroencephalogram) recordings measure the activity of large numbers of cells.
EEGs study brain activity through recordings from electrodes placed on the scalp.
Evoked potentials are an alteration in the EEG recoding produced in response to the
application of a particular stimulus.
Magnetoencephalography (MEG) allows researchers to record the brain’s magnetic
activity.
Repeated transcranial magnetic stimulation (rTMS) consists of magnetic pulses
delivered through a single coil of wire encased in plastic that is placed on the scalp.
A lesion is an injury to neural tissue and can be either naturally occurring or deliberately
produced.
Microdialysis is a technique for assessing the chemical composition of a very small area of
the brain.
One approach to the question of heredity versus environment is to compare the variable
of interest by using identical or fraternal twins. This natural comparison provides a fair
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amount of control because we can assume that wins enjoy similar prenatal and postal
environments. Although twins are not exposed to completely identical environments, the
environments experienced by twins are more similar than the environment of non-twin
siblings.
Another approach to quantifying the influences of heredity and environment is to compare
the similarities of an adopted individual to his or her biological and adoptive parents.
Similarities to the biological parents suggest a role for heredity, whereas similarities to the
adoptive parents suggest a role for the environment.
Heritability – the amount of variability of a trait in a population that is due to genetics.
Knockout genes – genes that take the place of normal genes that fail to produce the specific
protein produced by the normal genes.
A stem cell is an undifferentiated cell that can divide and differentiate into other types of
cells. Stem cells provide a promising method for repairing brain and spinal cord damage,
and can be derived from embryos, umbilical cord blood, and some adult tissues.
WEEK ONE – LECTURE NOTES
Structure of the Vertebrate Nervous System:
- Dorsal: toward the back (in humans: top of the head)
- Ventral: toward the stomach (in humans: bottom of the head)
- Anterior: toward the front end
- Posterior: toward the back end
- Lateral: toward the side
- Medial: toward the midline
Divisions of the Nervous System:
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Three main brain sections:
1. Hindbrain
2. Midbrain
3. Forebrain
Two Hemispheres: Each hemisphere controls the opposite half of the body
Contralateral: Controls the opposite side
Ipsilateral: Controls the same side
Four Lobes:
1. Frontal Lobe
2. Occipital Lobe
3. Parietal Lobe
4. Temporal Lobe
The hindbrain contains areas that regulate basic functions like heartbeat, circulation,
respiration, sleeping and some movement. Clearly, this area is really important for survival.
The Hindbrain sits just above the spinal cord. The hindbrain consists of three main
structures: Medulla 2) Pons 3) Cerebellum. Together, these form what is known as the brain
stem.
The medulla is located just above the spinal cord and really could be regarded as an
enlarged extension of the spinal cord. It’s responsible for vital reflexes such as breathing,
heart rate, vomiting, salivation, and coughing.
The pons lies above the medulla, and within both the pons and the medulla is another
structure called the reticular formation, which works to increase arousal and readiness of
other parts of the brain.
The largest part of the brain stem is the Cerebellum. It’s particularly important for helping
to regulate motor movement, balance and coordination.
The midbrain contains areas that appears to be involved in learning to create behaviours
that either minimise unpleasant (or aversive) consequences or maximise pleasant (or
rewarding) consequences. Although it is small relative to the hindbrain and particularly the
forebrain, it is comprised of several different critical structures: the tectum, superior and
inferior colliculus, tagmentum, and the substantia nigra. These regions are critical routes for
sensory information, and various homeostatic functions and reflexes.
The forebrain contains the thalamus, the hypothalamus and the cerebrum.
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The cerebrum is the large part that we usually think of when we think of the brain, and it
consists of the cerebral cortex as well as what are called subcortical structures such as the
limbic system and basal ganglia.
Diencephalon: the thalamus and the hypothalamus.
The thalamus is essentially the brain’s relay centre, as it initially processes almost all
sensory information before it is sent to specialised areas within the cerebral cortex.
Just below the thalamus is the hypothalamus, which helps in the regulation of behaviours
such as eating, drinking, sweating or shivering, sexual behaviour and so on, by conveying
messages to the pituitary gland to trigger the release of hormones.
Sitting laterally to the thalamus are the basal ganglia. The basal ganglia are associated with
planning of motor movement, and aspects of memory and emotional expression.
Connected to this is the amygdala, which is part of the limbic system, and is a small
almond shaped structure that appears to be particularly involved in emotional processing
and fear responses.
The occipital lobes are at the posterior end of the cerebral cortex. This brain region
contains the primary visual cortex, which means that visual sensory information is initially
sent to this region for processing.
The temporal lobes are along the sides of the brain, towards the bottom. The temporal
lobes are the target for auditory information and, in the left hemisphere in particular, are
especially involved in processing spoken language and semantic memory.
The frontal lobes are at the very front, or anterior, end of the cerebral cortex.
At the most anterior part of the frontal lobe is the prefrontal cortex, which seems to be
especially involved in higher functions, as well as for our short term, or working, memory
and for the regulation of impulses.
The most posterior part of the frontal lobe is the primary motor cortex. If you look at the
way the brain is constructed, it is comprised of lots of folds of tissue. The lower parts of
these folds – the grooves or valleys – are called sulci (pronounced sulk-ee), and the higher
parts of these folds – the mountains – are called gyri (pronounced j-eye-ree). There is a
fairly distinctive central sulcus – or groove – called the postcentral sulcus, which provides
an anatomical landmark for separating the frontal lobe from the parietal lobe. Just anterior
to this central sulcus is the primary motor cortex. This region is responsible for the control
of fine motor movement.
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Parietal Lobe: It is just posterior to the central sulcus. Just behind this is a long elevated
part called the postcentral gyrus, and it is along this gyrus that the primary somatosensory
cortex lies.
WEEK TWO – LECTURE NOTES
Case studies overview:
- A case study in biological psychology is of an individual who might be tested exhaustively
to
determine his or her cognitive abilities of various kinds, usually after some sort of brain
injury
- Because case studies are of individuals, one can always wonder if that individual is typical
- Because most brain injuries are unplanned, one does not have any evidence of the
cognitive
abilities on the same tests from before the injury. It could be that the individual was poor
on the
tests even before the injury.
What was Phineas Gage’s injury?
- Gage was using a crowbar to tamp down a gunpowder charge in a rock face
- The gunpowder exploded, probably from a spark, sending the crowbar through Gage’s
head
- Gage recovered consciousness within a few minutes and could speak
- Gage later developed a serious infection, but recovered
Why is Gage’s case important?
- It was consistent with other research showing that the frontal lobes are critical for
judgement,
for response inhibition, and for impulse control
- It likely encouraged the use of frontal lobotomy as a treatment for depression and other
psychoses
Did Gage ever recover?
- Macmillan (2008) said that Gage’s ability to hold the job of stagecoach driver, requiring
that he
keep passengers happy for the long duration of the trip, meant his judgement and impulse
control returned
- It is possible that the damaged left frontal lobe healed enough to support this recovery
- It is also possible that the intact right frontal lobe was able compensate for the damaged
left one
- Macmillan proposed that the structure of the stagecoach tasks helped with the recovery
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Who is JW?
- At age 16 he had his first epileptic seizure, after which his epilepsy became intractable
- At age 25 he had his corpus callosum cut to relieve the epilepsy; it worked!
What was JW’s injury?: Complete, surgical section of the corpus callosum (joins the two
hemispheres)
What was JW’s behaviour after the injury?
- JW’s behaviour is apparently normal
- But when information was restricted to one or othe ther hemisphere, Gazzaniga and others
found that JW has essentially two minds in the one head
Why is JW’s case important?
- It had massive repercussions for philosophy, especially of the mindbody problem
- It supported a monist, materialist account of mind
- The notion of different abilities in the two hemispheres became a meme, going far beyond
its
evidence, into realms including education and counselling, where it is essentially
nonsense
Did JW ever recover?: Gazzaniga (1998) said JW’s right hemisphere learned to speak
WEEK THREE – LECTURE NOTES
Judgement last to develop: the area of the brain that controls ‘executive functions’
including weighing long-term consequences and controlling impulses – is among the last to
fully mature.
What is in the brain?:
1. Grey matter:
- Nerve cell bodies
- Dendrites
- Glial cells
2. White matter:
- Axons
- Glial cells
Histology: the study of the microscopic anatomy of cells and tissues
Neurons: Characteristics and principle morphology:
- Electrically excitable
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- Use electro-chemical signals to receive, process, and transmit information
- Consist of a cell body (soma) with characteristic extensions
- Dendrites
- Axon
- Pre-synaptic ending/axon terminals
Neurons: Structural classification:
By number of extensions:
By Shape/look of the dendrites:
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Interneuron:
Sensory neuron:
Motor neuron:
Cerebral cortex: Histology
- Layer 1: mainly dendrites from pyramidal cells, no cell bodies
- Layer 2: Small pyramidal neurons  input layer (from other cortical layers)”
- Layer 3: Medium-sized pyramidal neurons  output layer (to other cortical areas)
- Layer 4: Input layer (from outside the cortex)
- Layer 5: Largest pyramidal neurons  output layer (output to brain stem, spinal cord, and
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subcortical nuclei)
- Layer 6: Pyramidal and other neurons  output layer (main output to thalamus)
Membrane Potential:
- Membrane:
- Skin of the cell
- Consists of lipids (fats) and proteins (chains of amino acids)
- Membrane potential:
- Difference in voltage between the cell’s inside and outside
Neurons at “rest”: Resting potential:
- Membrane is permeable to a only a subset of ions (K+)
- K+ movies out because of diffusion, but against electrical gradient
- Sodium-potassium pump (sodium-potassium adenosine triphosphatase (against their
diffusion gradient)  removing one positive charge carrier from the intracellular space
- Needs energy
- Na+ cannot get back in
- Maintains resting potential
- Resting potential = membrane potential of a resting cell
- Ca. -70 Mv
- Negativity is because of negatively charged anions, mainly proteins
Excursion: Bushman’s Poison
- Native to Africa
- Also known as Wintersweet
- Used as arrow poison
- Contains Ouabain that inhibits sodium-potassium-pump and therefore elevates
intracellular calcium
- Small doses used:
- To treat hypotension and cardiac arrhythmias
- Potentially as contraceptive: severe decrease in motility of spermatozoa
- Overdose
- Death by cardiac arrest
Graded potentials:
- State
- Weak input neuron is not firing
- Electrotonic Conduction
- Passive
- Rapid but graded (decays with distance from source)
Action potential:
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- Opening of voltage-gated Na+ cannels (fast acting)  envy of Na ions
- Clouse of voltage-gated Na channels. Opening of voltage-gated K channels  exit of K
ions
- Reinstating of resting potential via Na/K pump
Salutatory propagation: Action potentials revisited:
- Sheaths of myelin wrap around axon = myelinisation
- Contain fats and proteins  high resistance for ion (current) flow across membrane = no
action potentials, but rapid electrotonic conduction (graded potentials)
- Gaps between sheaths: nodes of Ranvier
- Allow for action potential
- Reamplify the degraded signal
= Salutatory propagation
Electric Neural Messaging:
- Graded potentials
- Decay while travelling away from source, but allow for:
- Temporal summation: several stimuli at the same source in quick succession
- Spatial summation: several stimuli at neighbouring sources simultaneously
- Rapid conduction
- Action potentials:
- No decay during propagation
- Initiation subject to refectory periods
- Absolute (ca. 1ms): no new AP can be elicited
- Relative (ca. 2-4ms): stronger stimulus needed for new AP
- Slow(er) propagation
- All-or-none law
- Shape and size independent from stimulus strength once elicited
Multiple Sclerosis (MS):
- Focal disintegration of myelin sheaths (demyelinating disease)
- Slows transmission of action potentials (information) within the nervous system
- Sensory and motoric symptoms
- Autoimmune disease: immune cells entering the brain bypassing the blood-brain barrier
and turn against healthy cells.
Blood-Brain Barrier:
- Protects the brain from viruses, bacteria, and chemicals that might damage the neurons
- Permits passive and active passage of substances that are essential for proper brain
functioning (eg oxygen, water, vitamins, glucose, amino acids)
- Enabled by glia cells (astrocytes)
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Staining:
- Golgi
- Nissl
- Layers of cortex
Graded Potentials: stimulation/input at soma or dentrite  depolatisation of membrane 
electrotonic conduction: very fast but graded, only suitable for short distances.
From Graded Potentials to Action Potentials: stimulation/input at soma or dentrite 
depolarisation of membrane  initiation of action potential  propagation along axon: not
graded, slower.
Neurons – Classifcation by Neurotransmitter Use:
- Glutamatergic neurons: glautamic acid (glutamate)
- Cholinergic neurons: acetylcholine (ACh)
- GABAergic neurons: Gamma-Aminobutyric acid (GABA)
WEEK FOUR – LECTURE NOTES
Synapse:
- Axon terminal of the signal-emitting neuron  pre-synaptic ending
- Synaptic gap
- Membrane of the signal-receiving cell  post-synaptic membrane
Types of Synapses – Electric Synapses (gap junctions):
- Exchange of ions through pores across an extremely narrow gap
- Bi-directional
- Mainly when rapid transfer and synchronised firing is important (eg heart beat)
Types of Synapses – Chemical Synapses:
- Transfer of neurotransmitter molecules through a cleft
- Uni-directional
Communication between neurons occurs at specialised junctions called synapses. The most
common type of synapse is the chemical synapse.
A cycle in the life of a prototypic chemical synapse:
1. Action potential is propagated over presynaptic membrane
2. Presynaptic terminal is depolarised  influx of Ca 2+
3. Ca 2+ promotes exocytosis (fusion of vesicles with the presynaptic membrane)  release
of transmitter into the cleft
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4. Binding of transmitter of receptor molecules in the postsynaptic membrane  channel
open  ions flow  initiate an excitatory or inhibitory postsynaptic potential
5. Excitatory or inhibitory postsynaptic potentials spread passively over dendrites and the
cell body to the axon hillock
6a. Enzyme present in the extracellular space breaks down excess transmitter
6b. Transmitter reuptake  slows synaptic action for next transmission
7. Transmitter binds to autoreceptors in the presynaptic action for next transmission
Receptor Families – Ionotropic Receptors:
- Neurotransmitter binds
- Channels open
- Ions flow across membrane
Receptor Families – Metabototropic Receptors:
- Neurotransmitters binds
- G-protein is activated
- G-protein subunits or intracellular messengers modulate ion channels
- Ion channel opens
- Ions flow across membrane
Ionotropic Receptors:
- Form ion channels
- Binding of a neurotransmitter (ligand) to the receptor  directly opens or closes a
transmembrane channel to allow ions to get into or out of the postsynaptic cell
- Acts very quickly
- PSP lasts only for tenths of milliseconds
Metabotropic receptors:
- Do not have ion channels
- Binding of a neurotransmitter to the receptor  activates G-proteins inside the
postsynaptic cell  activate second messenger(S)  may result in opening of an ion
channel
- Act more slowly
- PSP lasts longer (100 ms to minutes or longer)
Depolarisation = less negative  increased likelihood, that neuron will fire (excitatory
postsynaptic potential/EPSP).
Hyperpolarisation = more negative  decreased likelihood, that neuron will ire inhibitory
postsynaptic potential (IPSP).
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Neural Activity:
- Within a neuron: voltage-gated ion channels; action potentials  all-or-none principle
- Ionotropic receptors: ion channels are opened by neurotransmitter; short term effect
- Metabotropic receptors: ion channels are opened by helper molecules (second messengers)
- Between neurons: via synaptic connections
- Chemical synapse:
- Neutotransmitter-receptor systems
- Change in membrane potential of the target cell (post-synaptic potential/PSP), can result
in action potential
- Electrical synapse:
- Voltage-gated, free of transmitters
- Fast and synchronous spread of action potentials (bidirectional)
- Synchronisation of neuron clusters
Synaptic Depression:
- Decrease in post-synaptic activation
- Due to temporary depletion of neurotransmitters in the vesicles following rapid successive
stimulation
- Stimulus-specific  habituation
- Recovery phase for synapse
Sensitisation:
- Increase in post-synaptic activation
- Due to additional transmitter release of an interneuron following stimulation couple with
an “emotional” input
- Stimulus-unspecific
Neural Plasticity:
- The nervous system, in particular the connections between cells within the nervous system
(synapses), changes over time  lasting re-wiring of neural pathways
- Bases for learning and memory
- Long-term potentiation (LTP)
- Long-term depression (LTD)
Neurotransmitter:
- Chemical that is released by the presynaptic neuron to transmit information to the post
synaptic membrane  messenger
- Acts by changing the voltage or structure of the postsynaptic membrane  docks at
specific receptors
- Is removed from the postsynaptic membrane afterwards
Inhibitory and excitatory effects depend on receptor type in post-synaptic membrane.
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Acetylcholine:
- Excitatory effects in the parasympathetic autonomic nervous system: slows heart beat, aids
digestion
- Excitatory effects in the peripheral nervous system (motor neurons)  excitation and
contraction of muscles
- Excitatory and inhibitory effects in the central nervous system: depending on receptor type
Cholinergic Receptors – Nicotinic:
- Ionotropic
- Opens Na+ channels  excitatory
- In CNS and motor neurons
Cholinergic Receptors – Muscarinic:
- Metabotropic
- Excitatory and inhibitory types
- In CNS and autonomic nervous system
Dopamine:
- Binds to metabotropic receptors  excitatory and inhibitory effects
- Affects:
- Reward and pleasure system
- Movement control and emotional responses
- Associated with:
- Schizophrenia  surplus of dopamine
- Parkinson’s disease  dopamine deficiency
- Addiction  low dopamine levels
Serotonin:
- Binds to metabotropic receptors  excitatory and inhibitory effects
- Affects:
- Circadian rhythm  sleep inducing
- Emotional regulation
- Pain perception
- Perception of hunger and thirst
- Associated with:
- Depression  deficient activity of serotonergic synapses
- Overweight  low serotonin levels trigger carbohydrate cravings
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WEEK SIX – LECTURE NOTES
Neuronal Activity – Action Potentials:
- Discrete signal (voltage spike) that moves from the cell body of a neuron along its axon
- At the end of the axon it enables the release of neurotransmitters
Neuronal Activity – Postsynaptic Potentials:
- Neurotransmitters bring to the membrane of the postsynaptic cell
- Ion channels open and close leading to gradual changes in membrane potentials
Scalp electrodes as neural activity detectors – Action potentials:
- Duration less than 1 ms
- Random physical distribution of axons
- Neurons fire to slightly different times: action potentials cancel each other
- Not detectable
Scalp electrodes as neural activity detectors – Postsynaptic potentials:
- Duration of tens to hundreds of ms
- Limited to dendrites and cell bodies
- Summation possible
- Detectable
From Postsynaptic Potentials to EEG:
- Activity of one pyramid cell is not sufficient  summation of many required
- Occurring at about the same time
- Involving 10^3 10^6 neurons
- Neurons are roughly aligned with each other  parallel
Hans Berger (1873-1941): First to measure electrical currents from human scalps
Scalp Potentials – Depend On:
- Position and orientation of the dipoles
- Resistance and shape of everything between the dipole and the electrode(s): cerebral
membranes, cerebrospinal fluid, skull, and scalp
-Mostly recorded from several electrodes that are placed at standardised positions: 10-20
system and extensions
Clinical Applications:
- Neurological diagnoses:
- Epilepsy
- Dysfunctional sensory nerve conduction
- Creutzfeldt-Jakob disease
- Functional changes connected to head injuries, poisoning, or blood flow disorders
- Sleep research
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Summary of EEG:
- Recording of electrical changes caused by the activity of neurons at the scalp
- Measured EEG is the sum of synchronous activity of thousands of neurons that are parallel
to each other
- Signals are very small (in the order of 1 to 100 millionths of a volt) and must be amplified
Event-related potentials (ERPs):
- Brain responses time-locked to some event. This event may be:
- A sensory stimulus
- A mental event
- Or the omission of a stimulus
Doing an ERP Experiment:
- During a study the subject listens to or watches some stimuli
- These stimuli are called events
- Electrical activity from the rain is recorded to a number of these events
Obtaining ERPs:
- Consistent electrical changes can be seen by averaging together the electrical activity from
a certain number of these events
- This activity is seen as a series of positive and negative-going deflections
What do ERPs tell?:
- The timing and size of these deflections
- The location of this activity on the scalp
- Can be used to make inferences about:
- The time-course of processing in the brain
- The location of the source of this activity
Event-Related Potentials:
- Have great temporal resolution because they involve electrophysiology/electrical
recordings  spatial resolution is poor though.
- To find out how something works, temporal information is essential  ERPs are a
fundamental tool when we want to understand cognitive processing
Magnetic Resonance Imaging (MRI) consists of:
- A very strong magnet that builds up a stable and intense magnetic field
- Three weak(er) gradient magnets that build variable magnetic fields
- Radio frequency coils that transmit radio frequency waves into the body
The Making of MRI Pictures: Tissue specific radio frequency pulses  allows to create a
map of tissue types in the body/body part.
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Functional Magnetic Resonance Imaging (fMRI):
- Brain activity requires oxygen
- Increased brain activity results in increase blood flow to the areas that are active
- fMRI can detect changes in blood oxygenation levels that correlate with neural activity
with high spatial resolution: temporal resolution is very poor though
- The measurement of blood flow, blood volume and oxygen use is called and bloodoxygen-level-dependent (BOLD) signal
WEEK 8 – LECTURE NOTES
Ultimately, the purpose of a brain is to control behaviours, and behaviours are movements.
Basic unit – Neurons:
- Sensory neurons (afferent)
- Motor neurons (efferent)
- Interneurons (excitatory, inhibitory)
- Varies in sizes (0.004mm – 0.1mm) and shapes
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Voluntary movement - Organization of voluntary movement:
- Type of movement
- Phasic (transient, discrete movements)
- Static (e.g., stabilize joints)
- Planning
- Goal?
- Sequence?
- Direction?
- Speed of movement?
- Force?
- Timing/Duration?
- Execution
- Online feedback y/n?
- Stop movement
Voluntary movement: Integration of information from millions of sensory neurons 
action via motor neurons
Voluntary movement:
- A group of large subcortical structures in the forebrain, primal role is to select action by
releasing inhibitory influence on a motor system, critical for learning new skills :basal
ganglia
- Little brain, contributes to coordination, precision, and accurate timing, contains Purkinje
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cells, cerebellum
- Consist of grey matter, function includes memory, attention, perception, language,
consciousness, movement control: cerebral cortex
Cerebral cortex:
- Grey matter
- Cell bodies
- Sulci and gyri
Two halves, four lobes
- Judgement, planning, decision-making, inhibition, personality, motor output:
frontal lobe
- Touch, math, spatial reasoning: temporal lobe
- Language, hearing, visual memory: parietal lobe
- Vision: occipital lobe
Transcranial magnetic stimulation (TMS):
1. Assessment
- Corticospinal excitability
- cortical inhibition
- cortico-cortical interaction
2. Causality (disruption/virtual lesion)
3. Modulation/neuroplasticity
Modulation – Stroke:
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WEEK 10 & 11 – LECTURE NOTES
What is Emotion? An emotional state has four aspects:
- Cognition
- Readiness for action
- Feeling
- Physiological change
Psychophysiology:
- Electroencephalography (EEG)
- Electromyography (EMG)
- Electrooculography (EOG)
- Electrodermal activity (Skin Conductance)
- Cardiovascular activity
- Heart rate (EKG)
- Blood Pressure
- Plethysmography
Psychophysiology is the branch of physiology that is concerned with the relationship
between mental (psyche) and physical (physiological) processes; it is the scientific study of
the interaction between mind and body.
Psychophysiology measures:
- EDA from fingers for skin conductance response (SCR)
- EMG of the obicularis oculi for startle (under the eye)
- EKG for heart-rate and respiration for RSA
Neurophysiology of Reward:
- Olds and Milner (1954) placed rats in a Skinner box that allowed self-stimulation of the
brain by the pressing of a lever.
- Rats sometimes pressed the lever 2000 times per hour to stimulate the release of
dopamine in the nucleus accumbens.
- Other behaviours that release dopamine include sexual excitement, gambling, and video
games.
Opponent process theory: The original emotion is replaced by the opposite emotion as the
original emotion gradually decays. The opponent process has a long duration and
strengthens with repetition. This applies most clearly to pleasure and pain.
Repeated pleasure - Enjoyment decreases but the opponent process strengthens:
Changes in Affect Before, During and After Each Stimulation (Opiates) for the First Few
Experiences and After Many Experiences:
Period
First Few
After Many
Before
Resting state
Craving
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During
After
Rush, euphoria
Craving, resting state
Contentment
Abstinence-agony, craving
Repeated pain - Distress weakens but the opponent process strengthens (e.g., exercise,
acquired tastes):
Changes in Affect Before, During and After Each Stimulation (Sauna Bathing) for the First
Few Experiences and After Many Experiences:
Period
First Few
After Many
Before
Resting state
Resting state
During
Pain, burning
Hot, exciting
After
Relief, resting state
Exhilaration, resting state
What is Emotion?:
- According to the James-Lange theory:
- People with a weak autonomic or skeletal response should feel less emotion.
- Increasing one’s response should enhance an emotion.
- Panic attacks are marked by extreme sympathetic nervous system arousal.
- Only if perceived as occurring spontaneously.
- People with “pure autonomic failure” report feeling emotion less intensely.
BUT:
- Paralyzed people report feeling emotion to the same degree as prior to their injury
- Thus research is contradictory and suggests other factors are involved in the perception
of emotion.
The sympathetic and parasympathetic nervous systems.
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James-Lange theory:
The emotion that is felt is the label that we give the arousal of the organs and muscles
Cannon-Bard theory: - emotions are a response to a cognitive interpretation:
Schachter’s cognitive theory:
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Creating certain body actions may also slightly influence emotion:
- smiling slightly increases happiness.
- Inducing a frown leads to the rating of stimuli as slightly less pleasant.
Indicates that perception of the body's actions do contribute to emotional feeling
Facial feedback: Facial expressions may (a) induce or (b) intensify emotional experiences.
Effects are small to moderate, influence the early development of emotions, can be
voluntary or involuntary, and interact with other influences on emotion (physiological
activity, the interpretation of the situational context, the interpretation of physiological
changes, bodily responses, and vocal expressions).
What is Emotion?
- The limbic system includes the forebrain areas surrounding the thalamus and has
traditionally been regarded as critical for emotion.
- PET and fMRI studies also suggest many other areas of the cerebral cortex, especially the
frontal and temporal lobes, are activated during an emotional experience.
- In general, a single emotion increases activity in various parts of the brain
Activation of the frontal and temporal areas of the left hemisphere is associated with
“approach” and the Behavioral Activation System:
- Marked by low to moderate arousal.
- Characterizes either happiness or anger.
The Behavioral Inhibition System (BIS) is associated with increased activity of the frontal
and temporal lobe of the right hemisphere:
- Increases attention and arousal
- Inhibits action
- Stimulates emotions such as fear and disgust
Testosterone alters the way people respond to stimuli:
- Increased testosterone levels show:
- Increases in heart rate.
- The tendency to attend longer and more vigorously to situations related to conflict and
aggression.
- Testosterone may increase the response of the amygdala to angry expressions.
- Decreases the ability of the cerebral cortex to identify and regulate emotion.
What is Emotion?:
- Differences in frontal cortex activity relates to personality.
- People with greater activity in the left hemisphere tend to be happier, more out-going and
friendlier.
- People with greater right hemisphere activity tend to be socially withdrawn, less satisfied
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with life, and prone to unpleasant emotions.
- Damage to the right temporal cortex causes problems in the ability to identify emotions
of others.
- Emotions are adaptive (fear leads to escape, anger lead to attack, etc.)
- Another major function of emotion is to help us make decisions.
- The consequences of our decisions have emotional components.
- Emotions are an important component to moral decisions.
- Failure to anticipate the unpleasantness of an event can lead to bad decision making.
Attack and Escape Behaviors:
- Pain, threat or other unpleasant stimuli usually trigger an attack behaviour.
- Attack behaviours are associated with increased activity in the corticomedial area of the
amygdala.
Attack and Escape Behaviors:
- The startle reflex is the extremely fast response to unexpected loud noises  found in
young infants and thus unlearned.
- Auditory information stimulates an area of the pons that commands the tensing of the
neck and other muscles  Information reaches the pons within 3 to 8 milliseconds after
a loud noise.
- The startle response occurs within two-tenths of a second.
Benzodiazepines are the most commonly used anti-anxiety drugs:
- Benzodiazepines bind to the GABAA receptor complex, and facilitate the effects of
GABA.
- Benzodiazepines exert their effects in the amygdala, hypothalamus, midbrain, and other
areas.
Blink reflex:
- Is modified by positive and negative affect
- Is suppressed by a weak “pre-pulse” ~ 50 ms before the main stimulus – can be used as a
measure of inhibitory control
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- Ethyl alcohol has behavioral effects similar to benzodiazepines.
- Alcohol, benzodiazepines, and barbituates all exhibit cross-tolerance.
- Cross-tolerance is tolerance that develops to one drug when a similar drug is taken.
- Alcohol enhances GABA effects.
Orienting responses:
- Heart rate decreases
- Skin conductance increases
- Breathing stops momentarily
- Pupils dilate
Habituation: Orienting responses decrease with repetition of the stimulus
Attack and Escape Behaviors:
- Damage to the amygdala interferes with:
- the learning of fear responses
- retention of fear responses previously learned
- interpreting or understanding stimuli with emotional consequences
- fMRI studies of humans suggest the amygdala responds strongly to emotional stimuli and
facial expressions  Not necessarily associated with just fear.
- Activity is strongest when the meaning is unclear and requires some processing.
- In humans, damage to the amygdala does not result in the loss of emotion.
- Damage to the amygdala impairs the processing of emotional information when the
signals are subtle or complicated.
- Amygdala damage affects the ability to judge “trustworthiness” in people.
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- People with amygdala damage focus on emotional stimuli the same as irrelevant stimuli
or details.
- Amygdala damage also affects the ability to recognize emotions specifically in
photographs or pictures  Effect is particularly strong for fear or disgust.
- Amygdala damage does not affect the ability to recognize fear in real life  Attention to
certain aspects of the face (eyes versus mouth) may account for the difference.
- Genetic variations in amygdala arousal may thus underlie some of the variations of
anxiety in the population and related disorders.
- Arousal of the amygdala relates to the tendency to experience some negative emotions.
- Excessive fear and anxiety disorders are associated with hyperactivity in the amygdala
- Drugs intended to control anxiety alter activity at amygdala synapses.
- The main excitatory neuromodulator in the amygdala is CCK, and the main inhibitory
transmitter is GABA
- Injections of CCK-stimulating drugs into the amygdala enhance the startle response.
- Drugs that increase GABA activity block panic.
Social Anxiety Disorder – Symptoms:
- Excessive blushing
- Sweating
- Trembling
- Palpitations
- Nausea
- Stammering and/or rapid speech
- Panic Attacks
Blushing:
- People who are frightened of blushing overestimate how much they are blushing
- Blushing may be a “hardwired” non-verbal form of appeasement
PTSD:
- Posttraumatic stress disorder (PTSD) occurs in some people after terrifying experiences
and includes the following symptoms:
- Frequent distressing recollections.
- Nightmares.
- Avoidance of reminders of the event.
- Exaggerated arousal in response to noises and other stimuli.
- Studies have revealed most PTSD victims have a smaller than average hippocampus.
- PTSD victims show lower than normal cortisol levels after the trauma.
- People with low cortisol levels may be ill-equipped to combat stress and more prone to
the damaging effects of stress.
- Prolonged stress can be harmful to the hippocampus and can affect memory.
- Cortisol enhances metabolic activity in the body.
- When metabolic activity is high in the hippocampus, the neurons are more sensitive to
damage by toxins or over-stimulation.
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- Stress also impairs the adaptability and the production of new hippocampal neurons.
Psychophysiological Correlates of EMDR Therapy to Treat Trauma in Timor Leste:
- Eye movement sets were associated with an immediate significant decrease in heart rate
and an increase in skin conductance
- This response habituated within and across eye movement sets
Gene:
- One gene identified controls the serotonin transporter protein. This protein controls
the ability of the axon to reabsorb the neurotransmitter after its release.
- Two “short forms” of the gene are associated with an increased likelihood of depression
after stressful events  May alters people’s reactions to stressful events or make them
more sensitive to environmental influences
Mood Disorders:
- Major depression - feeling sad and helpless everyday for weeks and includes the
following characteristics:
- Little energy.
- Feelings of worthlessness.
- Suicidal thoughts
- Feelings of hopelessness.
- Difficulty sleeping.
- Difficulty concentrating.
- Little pleasure
- Similar symptoms can result from hormonal problems, head injuries, brain tumors,
substance abuse, or other illnesses.
- Absence of happiness is a more reliable symptom than increased sadness.
- Occurs at any age, but uncommon in children
- Twice as common in women
- 10% lifetime prevalence.
Depression is also associated with the following brain activity:
- Decreased activity in the left prefrontal cortex.
- Increased activity in the right prefrontal cortex.
Many drugs used to treat psychiatric disorders discovered by accident - Categories of
antidepressant drugs include:
- Tricyclics.
- Selective serotonin reuptake inhibitors.
- MAOI’s.
- Atypical antidepressants.
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- Studies indicate half of people show a good response within weeks after use of
antidepressant drugs.
- About same percentage respond to therapy
- 30% respond to a placebo
- A combination of both benefits only a slightly higher percentage
- Little difference regarding the various types of antidepressant drug
Mood Disorders - Benefits of antidepressant drugs are greatest for people with severe
depression:
- Antidepressants are generally ineffective for people who suffered abuse, neglect, or other
trauma during early childhood. Usually respond better to psychotherapy  Use of
antidepressants in children controversial as they can sometimes increase suicidal
thoughts
- Exactly how antidepressant drugs work is unclear.
- They alter synaptic activity quickly but the effects on behaviour are not derived until
weeks later.
- Reveals depression is not directly and solely the result of low serotonin levels.
- Blood samples show normal levels of serotonin turnover in depressed people.
- In some depressed people, neurons in the hippocampus and the cerebral cortex shrink.
- Behavioural effects of antidepressant drugs often take longer than the effect on our
neurochemistry which happen within hours
- One explanation is that antidepressant drugs increases the release of BDNF which
promotes neuron growth and survival.
Seasonal affective disorder (SAD) is a form of depression that regularly occurs during a
particular season:
- Patients with SAD have phase-delayed sleep and temperature rhythms; most depressed
people have phase-advanced patterns.
- Treatment often includes the use of very bright lights.
- Most likely explanation is that the light affects serotonin synapses and alters circadian
rhythms.
A night of total sleep deprivation is the quickest method of relieving depression:
- Increases proliferation of new neurons in the hippocampus
- Half become depressed again after the next night’s sleep.
- Extended benefits derived from altering sleep schedule on subsequent days and
combining sleep alteration with drug therapies
- Exact mechanisms are not unknown.
Unipolar disorder is characterized by alternating states of normality and depression.
Bipolar disorder (manic-depressive disorder) is characterized by the alternating states of
depression and mania  Mania - restless activity, excitement, laughter, self-confidence,
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rambling speech, and loss of inhibition.
Research suggests a heritability basis for bipolar disorder (Craddock & Jones, 1999).
- Twin studies suggest monozygotic twins share a 50% concordance rate.
- Dizygotic twins, brothers, sisters or children share a concordance rate of 5-10%.
- Comparison of chromosomes have identified several genes that are somewhat more
common in people with the disorder.
- Genes simply increase the risk but do not cause the disorder.
Treatments for bipolar include:
- Lithium - a salt that stabilizes mood and prevents relapse in mania or depression
- Drugs - anticonvulsant drugs such as valproate and carbamazepine
Drugs work by:
- decreasing glutamate activity
- blocking the synthesis of the brain chemical arachidonic acid, which is produced during
brain inflammation.
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