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Neuroscience
Week 1 - Neuroanatomy
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Neuroanatomy - Gross anatomy - overall structures that can be seen by eye, Microscopic cellular connections between cells
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PNS - Nerves from limbs and organs - communicates information to/from CNS
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The
autonomic nervous system (PNS) controls internal functions e
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, internal organs, glands
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Major brain structures - cerebrum, brainstem, cerebellum
Brain lobes - Frontal lobe, lateral fissure, temporal lobe, cerebellum, occipital love, parietal
lobe, central fissure
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Sulci - depression/fissures in the surface of the brain
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Brain is split into 2 hemispheres, separated by the interhemispheric fissure by connected by
corpus callosum
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They
both process visual information differently
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Cranial nerves - nerves bring visual, auditory and olfactory information and control facial
muscles and sensation as wbell as other structures
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Temporal language, object recognition, hearing, parietal - spatial, perception, attention, sense of touch,
occipital - vision
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Week 2 - Electrical Brain
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Surface of the brain - under the skull, the brain is surrounded by a 3-layer coating called
meninges
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Electrical signalling - To achieve rapid, long-distance communication, neurons have evolved
the ability to send electrical signal
Neurons - brain cells
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Basic building block of the nervous system, specialised for
information transmission throughout the brain and body
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Axons: projection from the soma that sends signals to
other neurons
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Dendrites
interface with axons at synaptic junctions
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Types of neurons - Sensory: receive sensory signals
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Interneuron:
connects neurons within the brain and spinal cord
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There is now evidence they are also involved in communication
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Microglia: immune cells of the brain
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Plasma membrane of neurons - A membrane separates intracellular and extracellular space
(fluid) allowing a cell to function as an independent unit
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It
regulates the concentration of water, salts and other chemicals on each side of the membrane
(i
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, inside and outside the cell) Only a few molecules (O2, CO2, glucose) can pass across the
membrane unassisted
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Ions - The movement of ions across the plasma membrane allows electrical signalling to occur
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Movement affected by concentration gradient,
diffusion, electrical charge
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Resting membrane potential - -70mV
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The movement of ions across the plasma membrane of neurons creates
electrical activity
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The
resting membrane potential is maintained by channels, gates and pumps in the plasma
membrane
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Ungated K+
channels allows K+ to move freely across the membrane, but Na+ is kept out
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Graded potentials - Hyperpolarisation: an increase in the charge (polarity) of the membrane to
make it more negative Caused by: Outward movement (efflux) of K+ through passive K+
channels; inward movement (influx) of Cl- through passive Cl- channels
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Caused by: influx of Na+
through (normally closed) Na+-gated channels
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It is
the electrical signal that conveys information
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Once a
threshold is reached (~-50mV), voltage-sensitive Na+ channels open allowing more Na+ to rush
into the cell This produces a large shift in the polarity of the neuron From this point on, it is an
all-or-nothing response
Repolarisation - Repolarisation: Once the polarity reaches a peak of ~+30-50mV, Na+ channels
are inactivated
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Hyperpolarisation -The voltage of the membrane reverses again, and now goes slightly below
the resting potential, to ~-80mV before returning to the resting baseline
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Relative refractory period = the state of the axon during repolarisation when a

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larger than normal electrical current is required to produce an action potential
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The refractory period ensures the action potential travels in one direction
only
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Results in saltatory conduction - action potential jumping from
node to node, increases speed action potential can travel along axon
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The action potential sent down the an axon reaches
the axon terminal
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The small (~ nanometers) gap = synaptic cleft
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 The electrical signal is converted to a chemical signal to
link the action potential of one neuron with a synaptic potential in another neuron
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Electrical signal can pass directly between neurons and
eliminates the ~5ms it takes for chemical signalling
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 They can have an excitatory or inhibitory effect
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Neurotransmission - 4 steps in transmitting information across a chemical synapse:
Neurotransmitter synthesis and storage - Some neurotransmitters are synthesised in the soma
and are transported to the axon terminal along microtubules
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In the axon terminal, all neurotransmitters are stored in
vesicles
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Neurotransmitter release - When the action potential reaches the axon terminal, voltage
changes on the presynaptic membrane set off a series of processes to release
neurotransmitter, held in vesicles, into the synaptic cleft: The presynaptic membrane has
many voltage-sensitive calcium (Ca2+) channels that open in response to the membrane
voltage change (from the incoming action potential) The opening of Ca2+ channels causes and

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influx of Ca2+ into the axon terminal
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The vesicles fuse with the presynaptic
membrane to release their contents into the synaptic cleft = exocytosis
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It binds
with specialised protein receptors that are embedded in the postsynaptic membrane
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There are 3 effects receptor binding can have
on the postsynaptic membrane
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Hyperpolarisation of the postsynaptic membrane to inhibit the
postsynaptic neuron
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Neurotransmitter deactivation -  Neurotransmitter in the synaptic cleft must be removed to
stop the occupation and stimulation of receptors
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Degradation: enzymes in the synaptic
cleft break down neurotransmitters
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Re-uptake: transporters on the presynaptic
membrane bind neurotransmitters and return them to the presynaptic terminal for re-use
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Glial uptake: neurotransmitters can be taken up by nearby glial
cells which can then be returned to the axon terminal
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The result can be graded potentials that increase or decease the
likelihood of an action potential being produced
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An inhibitory postsynaptic potential (IPSP) is produced via Cl- influx or K+ efflux
(hyperpolarisation)
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An action potential is produced
when enough EPSPs sum to reach the activation threshold
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  Spatial
summation: Graded potentials that occur at approximately the same location on a membrane
are summed
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Learning is a relatively permanent change in behaviour that results

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from experience
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Habituation - A weakened response to a stimulus as a result of repeated presentations
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EPSPs in the motor neuron become smaller
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If less neurotransmitter is being received by
the postsynaptic motor neuron, then changes must be taking place in the presynaptic sensory
neuron
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This means less neurotransmitter release
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This results in the K+ channels being less responsive, so less K+ efflux = slower repolarisation
(step 2 of action potential) This now results in the action potential lasting longer, which means
more Ca2+ influx and more neurotransmitter release
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Long-term habituation and sensitisation produced structural changes - Habituation causes a
reduction in the number of synapses (via reduction in dendrites)
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4 Major systems - Cholinergic system, Noradrenergic system, Serotonergic system,
Dopaminergic system
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In the CNS it is involved in attention, sleep/wakefulness, perception, memory
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In the CNS it is involved in alertness, arousal, decision-making and
reward
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Increases level of circulating
free fatty acids that can be used by the body as fuel in times of stress or danger to increase
alertness and exertion
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In the CNS it is involved in controlling appetite, sleep, memory and
learning, mood, temperature regulation
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Nigrostriatal
pathway (orange): involved in movement
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Week 6 -Neuromethods
Imaging
 spatial resolution - detail that can be seen, more detail = more localisation
 Temporal resolution - temporal resolution gives you varying levels of information about the
changes that take place in neuronal activity across time
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Faster scans give the most accurate representation of changes and thus have
higher temporal resolution
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Better to define
region of interest before analysis
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More dense material absorbs
more x-ray
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 Advantages - can be used on all individuals
 Disadvantages - Involves x-rays, low spatial resolution, not provide information about
temporal changes in the brain
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MRI SCAN
 Uses magnetic fields to visualise the brain
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 Requires use of 3 different magnetic fields to produce an image of the brain
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Reads radio waves
o Gradient field - varies in intensity, provided ability to localise points
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 When magnetised, molecule in the brain respond to exposure to radio waves at a particular
frequency by sending back a radio wave signal called a spin echo
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 Advantages - Precise anatomical image, high spatial resolution, can map different substances,
non-invasive
 Disadvantages - Poor temporal resolution, cannot be

Week 7 - Neuromethods
PET Scans:
 Positron emission tomography
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Relies on
radiation emitted from substances introduced to the brain by injection
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 Radioactive substances release positrons, when these collide with an electron they release 2
photons of light which travel way from the collision sight at 180degrees from each other
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 Spatial resolutions - better than most EEG or ERP techniques
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Resolution sufficient to say which part of the brain responsible for
behaviour
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Detecting changes in
regional cerebral flow or metabolism not activation of neurones
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 Advantages - Used to assess many aspects of function
 Disadvantages - Involved use of ionising radiation and cannot be used to often
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Often requires
averaging data across individuals
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Requires an on-site
cyclotron to create radio-isotopes
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Requires an injection
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 Active brain areas require energy, energy carried in oxygen in blood
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MRI detect changes in blood flow by detecting change in magnetic
fields
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 Advantages - precise anatomical images with high spatial and higher temporal resolution than
PET images produced
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Non-invasive
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NIRS
 Near infra red spectroscopy
 Uses pulses of near infra red light that penetrate the skull
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Optical sensor used to detect
photons reflected through the skull
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 Advantages - Functional image with moderate spatial and high temporal resolution, noninvasive, portable, used with children and infants
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 Dected in 2 ways - slow signal 0 changes in blood flow to areas of brain, fast signal - detects
physiological changes with activity
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Electrodes are often clipped or sown into a cap
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 Measures - the activity of populations of neurones firing together produces a change in
electrical polarisation in the brain
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 Frequency bands - brain produces synchronized activity in different frequency bands
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o Beta - motor behaviour, concentration, alert, 15-30Hz
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Dreaming - More active brain, EEG shows
small amplitude, fast changes in electrical activity
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 Limitations - spatial resolution - electrical signals have to pas through lots of tissues before
they can be measured
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o Disadvantages - very poor spatial resolution, difficult to tell what part of the brain is
responsible for state changes, does not show the response to specific stimuli
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 Neural response to a single event is very small in comparison to the background EEG activity
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 ERP components - different components of the ERP are related to different mental processes:
o sensory component's - occur 0-100ms after a stimulus and are associated with sensory
processing in primary cortices
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o Mismatch negativity - occurs 200-300ms after stimulus and occurs when stimulus deviates
from expected
o P3 - Occur 300-800ms after Stimulus and is associated with memory updating
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Clinical
disorders - changes in waveforms different in psychiatric disorders e
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Schizophrenia or
phobia
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 Disadvantages - very poor spatial resolutions - difficult to ell what part of the brain is
responsible for state changes
Magntoncephalography - MEG
 MEG Signal derived from the same source as the EEG signal
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Users sit head in helmet, fixed sensors, SQUIDs used to detect small magnetic fields,
magnetically shielded rooms used
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Temporal resolution is excellent
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Uses of MEG - Many different cognitive processes and disorders including epilepsy, to localise
the epileptogenic regions of the brain, and Alzheimer's diseases to predict which individuals
will develop the disease
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Week 9 - Electrophysiology and Optogenetics
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Electrophysiology - single cell recording
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Techniques include single cell recording,
electroencephalography (EEG), event related potentials (ERPs) and magnetoencephalography
(MEG) All of these techniques have good temporal resolution they are able to track changes in
the brain across time
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This technique is
limited to recordings made in animals and limited human populations under very special
conditions
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A baseline recording is taken to establish the resting firing rate of the neuron
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This establishes the function of the neuron
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For instance, a neuron in the visual
system might respond to a small portion of visual space that is imaged on the fovea, or a much
larger area of the peripheral retina
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Excitatory or inhibitory - It is worth noting that placing an appropriate stimulus in a cell’s
receptive field can cause the firing rate to increase (excitatory response) or decrease
(inhibitory response)
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It can be used to investigate the function of single neurons
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Positives: Excellent temporal resolution, Excellent
spatial resolution
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  Based on
the discovery that light can activate proteins
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Channelrhodopsin (ChR2) receptor:  Opens channel when stimulated by blue light, Sodium
ions pass into the neuron causing it to fire
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Reward: Relevant to reward-related pathologies involved in depression and in substance
abuse, as well as in healthy reward processes
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Negatives: Invasive and early days, so can only be used on animals at the moment
Positives: Can be used to manipulate neural activation, Excellent temporal resolution,
Excellent spatial resolution
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Subjects are individuals with damage to their brain resulting from a
neurological condition, head trauma, or stroke
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Strokes - 2 types - Ischemic - a clot blocks blood flow to an area of the brain or Haemorrhagic bleeding occurs inside or around brain tissue
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Problems with clinical lesion studies - The extent of brain damage is not always clear, and a
lesion may affect more than one brain network, so the behavioural effects of a lesion cannot
always be attributed to a distinct region
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Advantages - can provide evidence of functional dissociations
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Given brain plasticity, connections might be modified following
lesions
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Precise positioning achieved using Stereotaxic equipment
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Radio frequency lesion: an electrode is inserted to the correct location and then the
tip is heated destroying nearby cells
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Advantages - Can provide evidence of functional dissociations
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Deliberate lesioning of human brain not allowed
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Sample size can be relatively large
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By
damaging a structure we might also be damaging fibre pathways between other areas
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Neurophysiological methods - TMS - Transcranial Magnetic Stimulation
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The effects of this stimulation can tell us
about what the area of the brain is doing
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The current produces a
magnetic field
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Used as a treatment for depression and Auditory hallucinations in schizophrenia
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Disadvantages - effect of the stimulation is limited to superficial cortical regions
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