Download Brain research methods

Madeleine Wright
Structural and Functional
nueroimaging
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Structural- refers to scanning techniques that
show brain structure and anatomy.Scans produced
by these techniques typically show cross sections
of the brain and may look as if someone has sliced
through the brain and taken a picture.
 Examples: MRI and CT
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Functional- refers to scanning techniques that
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provide views of some particular aspects of brain
funtion by images of the brain ‘at work’. They also
provide information about brain structure.
Examples: PET,SPECT and FMRI
Direct electrode stimulation
Involves using a device that emits a weak electric
current to activate or disrupt the normal activity of
neurons in a specific brain area. The brain area
initiates a response which is then assumed the area
controls or is involved in that responses. It may not just
initiate the response it may also disrupt the functioning.
 A electrode is a small, electrified fine wire (or disc) that
can be inserted into or placed onto a specific area of
the brain, that stimulates a specific brain area.
 The brain does not contain pain receptors therefore
patients can remain conscious during brain surgery.
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Example : Penfield
- Brain map which was used to identify areas
of the cerebral cortex responsible for
different functions.
- Did a study with epilepsy in which he
mapped cortical areas and related functions
to see what area was responsible for the
response.
- Advantages: The research may promote
futher experiments to test the possibilty of a
brain pacemaker that regulates chrome
(long-term) cases of depression

Advantages: The research may promote
further experiments to test the possibility of a
brain pacemaker that regulates chrome
(long-term) cases of depression
 Limitations- Invasive, they had to enter the
brain by opening the brain and activating or
disrupting specific brain areas to observe
any changes in behaviour.
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Transcranial magnetic
stimulation
(TMS)
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Delivers a magnetic field impulse through
the skull and temporally activates or
disrupts the normal activity of neurons in a
specific area of the cerebral cortex.
- harmless electric current in time
varying changes.
- person fully awake
- Non-invasive, no anaesthetic
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2 types
Single pulse –involves the delivery of a
single pulse
Repetive TMS (rTMS) – repeated but not
necessarily rapid, delivery of a pulse. When rTMS is
used, the consecutive pulses cause the neurons to lose
their ability to fire. It can uses to study how the brain
organises different functions such as language, memory,
vision or attention
A bride single pulse can cause a burst of brain activity
The pulse does not directly affect the whole brain. It only
affects that part of the brain that lies immediately below
the skull
Used to study functions of specific areas of
the cerebral cortex
 As with electrode stimulation, TMS can be
used for mapping brain areas. This is
performed by changing the coil position while
observing its effects.

Limitations
Advantages
-Extremely invasive research
procedure, which uses methods that
ethical standards today would be
considered unacceptable
- Difficulties in generalising results
- Cant be used with individuals who
have and metal in their body
-Very effective technique for brain
research
-The use of electrodes have been
useful and reliable
-Has advanced understanding of the
role of the brain in mental processes
and behaviour
-Identify the locations and functions of
numerous brain structures and areas,
as well as hemispheric specialisation
for different functions
-Results are generally very consistent
EEG(electroencephalograph)

Detects amplifies and records brain activity
Assist with the diagnosis and psychological study of
various brain related medial conditions, including brain
damage and neurological disorders such as epilepsy
and Parkinson's disease.
 Detect and identify distinctive patterns of electrical
activity in the brain occurring in people with depression
or schizophrenia
 Useful in providing general and overall info about brain
activity without being non invasive.
 Also used to study ongoing activity in the brain while the
participant perform long, complex tasks.
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Valuable information about:
-Different levels of brain activity associated
with various -Thoughts
-Feelings
-Behaviours
-Hemispheric specialisation
Advantages
Limitations
- Provides a summary of all
the activity of neurons firing
within the brain. Using an
EGG to understand the
workings of the brain.
-Does not provide a
summary of all the activity
of neurons firing within the
brain are activated and
what their specific functions
might be
-Difficult to pinpoint the
specific area of the brain
that is the source of the
brain wave activity
Computerised tomography (CT)
or Computerised axial tomography (CAT)
A neuroimaging technique that produces a
computer enhanced image of a cross
section (‘slice’) of the brain from X-rays
taken from different angles.
 The procedure involves moving an X-ray
source in an arc around the head while a
computer complies different ‘snapshots’ of
the brain area being investigated

Procedure
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The patient must be given an injection of a substance into the vein
of their arm or hand.
- used to highlight the brains blood vessel
The patient is required to lie very still on the CT scan bed with their
head inserted into the scanner opening
An X-ray source is slowly moved in a circular path around the head,
at each position delivering a small amount of radiation, which
passes through the head and brain
An X-ray detector opposite the X-ray source analyses the amount
of radiation that has passed through the brain.
The X-ray source and detectors are than moved to a new position,
and this is repeated many times.
A computor then combines the many cross-sectional images taken
from all the different angles around the head into a composite
cross-sectional, two-dimensional or 3D image
Advantages
Limitations
-Is a way of looking a live intact human
brain without using invasive, often
dangerous procedure
-Radiation dosage, relatively harmless
-Useful for spotting and identifying the
precise location and extent of damage
to or abnormalities in various brain
structures or area.
-Identify the location and size of
tumours
-Identify abnormalities in brain
structures among people with a mental
illness, schizophrenia and depression
-Requires an injection but is
considered non-invasive
- It shows only brain structure or
anatomy. It does not provide
information about the activity of the
brain; that is, brain function
Magnetic resonance imaging
(MRI)
A neuroimaging technique that uses harmless
magnetic fields and radio waves to vibrate atoms in the
brain neurons to produce an image of the brain
 These vibrations are detected by a huge magnet in the
chamber surrounding the motionless person, and are
channelled into a computer
- which then assembles them into a coloured image
that indicates areas of high and low brain activity
 MRI provides an image of the brain and structures that
is clearer and more detailed than CT
 Structure

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CT and MRI are used for diagnosing structural abnormalities if the
brain. However a MRI can be used to detect and display extremely
small changes in the brain
Clearly distinguish between brain tissue that is cancerous and noncancerous.
Advantages
Limitations
-Enabled even more
precision in the study of the
structure of the live human
brain in a non-invasive and
harmless way
-Provides detailed and
clearer images of the brain
-Doesn't use X-rays or
radioactive substances
-Can not be used with
people who have internal
metallic devices
-It only shows brain
structure, or anatomy, and
not funtion
-Does not reveal whether
the structures are invloved
in any given mental process
or behaviour
Positron emission tomography
(PET)
Is a neuroimaging technique that uses a radioactive
tracer to enable production of a computer-generated
image that provides information about brain structure,
activity and function during various tasks
 PET is used to record the levels of activity in different
areas of the brain while the patient is involved in a
cognitive or behavioural activity if some kind, such as
thinking, imagining, remembering etc.
 Provides images of the ‘working brain’ by tracking
blood flow around the brain
- brain areas that require increased blood flow have
increased neuronal activity.
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Prior to the PET procedure, a harmless radioactive substance is
injected into the participants blood vessels
- Substance enters the bloodstream it travels to the brain
Each PET scan uses a colour code to indicate different levels of
brain activity:
Advantages
Limitations
-Useful technique for brain study
-Enable researches to obtain valuable
info about the role of the brain in
behaviour and mental processes
-Enables detailed images of the
functioning brain; ‘brain at work’
-Observe different brain areas that
interact when a person is required to
do certain task
-More sensitive in detecting areas of
brain damage than CT and MRI
-Colour coding in PET scans makes it
relatively simple to identify areas of
the brain that are more active and
inactive
-Researches can not determine
whether an active brain area is
actually involved in the mental process
or behaviour under investigation
-No scope for suggesting cause-effect
relationship between active or inactive
areas
-Limited to studying relativley short
tasks
-Require an injection of radioactive
substance but harmless
Single photon emission computed
tomography (SPECT)
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Variation of the PET
Uses a longer lasting radioactive tracer and a scanner to record
data that a computer uses to construct two or three-dimensional
images of active brain regions
SPECT images are not as good as PET images- have a lower
resolution
Advantages
Can also be given longer lasting tasks in research studies
Less expensive to uses than PET
Functional magnetic resonance
imaging (fMRI)
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Structure and funtion
Is a nureoimaging technique that enables the
identification of brain areas that are particularly active
during a given task by detecting changes in oxygen
levels in the blood flowing through the brain
Bases on MRI and measures subtle changes in blood
oxygen levels in the functioning brain
The colour variations reflect the level of activity of
different brain areas and structures while the
participant engages in various experimental tasks
fMRI images of the brain structure and activity are
highly detailed and more precise
Advantages
Limations
-It can take numerous pictures of the
brain in rapid succession and
therefore can detect brain changes
from moment to moment
-Unlike PET, SPECT, the fMRI does
not require exposure to radiation
-Enables detailed images of
behavioural responses
-The uses of colour makes it easier to
interpret images
- Their is no scope for suggesting
cause-effect relationship between
active and inactive areas and mental
processes and behaviours under
investigation