Brain Research Methods - Psy

Report
BRAIN RESEARCH
METHODS
AMY COOPER
GLOSSARY
PG 1 –
PG 2 –
PG 3 –
PG 4 –
Direct Brain Stimulation
Electrode Stimulation
Direct Brain Stimulation
Transcranial Magnetic
Stimulation (TMS)
PG 5 – Procedure of TMS
PG 6 – Pros and Cons of TMS
PG 7 – Electroencephalography
(EEG)
PG 8 – Procedure of EEG
PG 9 – Pros and Cons of EEG
PG 10 – Computerised
Tomography (CT)
PG 11 – Procedure of CT
PG 12 – Pros and Cons of CT
PG 13 – Magnetic Resonance
Imaging (MRI)
PG 14 – Procedure of MRI
PG 15 – Pros and Cons of MRI
PG 16 – Positron Emission
Tomography (PET)
PG 17 – Procedure of PET
PG 18 – Pros and Cons of PET
PG 19 – Single Photon Emission
Computed Tomography
(SPECT)
PG 20 – Procedure of SPECT
PG 21 – Pros and Cons of SPECT
PG 22 – Functional Magnetic
Resonance Imaging (fMRI)
PG 23 – Pros and Cons of fMRI
DIRECT BRAIN STIMULATION
Using device that emits a
weak electric current to
activate/disrupt the
normal activity of
neurons in specific brain
area’s
Can be done by using
electrode or pulses of
transcranial magnetic
stimulation
Direct stimulation of a specific brain area controls/involved with response and
may also disrupt functioning of the specific area, thereby impairing the
response. Disruptive effect only apparent when person is actively engaged in
the behaviour being disrupted/impaired
Disruptive effect
most evident in
complex
functions such
as language
and memory
ELECTRODE STIMULATION
Electrode is a
small, electrified
fine wire which is
inserted
into/placed onto
a specific area of
the brain
STIMULATION OF:
Electrode used to
deliver a precisely
regulated electric
current to the brain
area stimulating a
specific brain area
Occipital Lobe – patients reported seeing flickering
lights, spots and colours
Auditory Cortex – ‘hearing’ doorbells, car engines
Somatosensory Cortex – ‘feeling’ a tingling sensation in
various parts of the body
Primary Motor Cortex – patients responded by moving
specific body parts
Wilder Penfield in 1940’s to
1960’s used technique to
locate and identify area’s of
the cerebral cortex
responsible for different
functions – producing a
‘map’ of the cortex to treat
epilepsy. Treatment involved
surgically removing area of
cortex that’s the source of
the epileptic seizures as a
last resort for patients. When
stimulated area of the
cortex Penfield ask patients
to report their experiences
Electrodes also used for therapeutic purposes in a procedure involving deep brain stimulation ie.
Stimulation served to reduce activity in area believed to over activate depression – patients almost
immediately after reported mental experiences such as a sense of ‘connectedness’
TRANSCRANIAL MAGNETIC
STIMULATION (TMS)
TMS is a direct brainstimulation technique
that delivers a magnetic
field through the scull
and temporarily
activates/disrupts
normal activity of
neurons in specific
areas of the cerebral
cortex
TMS only stimulates part
of brain that lies 2-3 cm
into brain directly
beneath coil.
Researchers can use
TMS to study functions of
specific areas of the
cerebral cortex
o The magnetic field includes a harmless
electric current in time-varying charges
o Can be used for mapping brain areas,
pinpoint/diagnose brain damage and to
track patients recovery ie. From a stroke
o Repetitive TMS (rTMS) used in procedures
involving repeated (not necessarily rapid)
delivery of a pulse causing area of brain to
be inactive without unwanted side effects
– used to study brain organisation, treating
serious cases of depression and is capable
of changing the activity in brain area
CEREBRAL CORTEXT ACTIVATION FOR A SHORT PERIOD
The magnetic field pulse is transmitted from a small copper
electromagnetic coil that is enclosed in plastic and placed next to
scalp.
An electric current is sent through the coil, which induces a magnetic
field around the coil and creates the pulse. The single pules is then
directed through the skin and scalp to underlying clusters of neurons;
activating the neurons and they send a burst if neural impulses
(electrical activity) to adjacent neurons, activating them – brief single
pulse can cause a burst in brain activity
PROCEDURE OF
TRANSCRANIAL MAGNETIC
STIMULATION (TMS)
PRIOR TO THE TREATMENT
The psychiatrist will first
give the patient a motor
threshold test
(determining the
magnetic field strength
required to cause
movement in patients
thumb). This test
determines the magnetic
field strength that will be
used in the patient’s
treatment.
After the motor threshold
test, the doctor will then
determine where to place
the treatment coil on
patients head to provide
the best treatment
DURING THE TREATMENT
During the TMS procedure, the patient will sit in a chair,
awake and alert during the entire treatment. They will
then wear earplugs because of a tapping sound made
by the machine
AFTER THE TREATMENT
During the treatment some patients may feel mild to
moderate scalp discomfort, which can be eased with
any pain relief medication (ie Aspirin) Patient can
return to your normal activity (ie driving) immediately
after the procedure
TRANSCRANIAL MAGNETIC
STIMULATION (TMS)
ADVANTAGES
LIMITAIONS
o Effective and reliable technique
of brain research
o Non-invasive procedure
o No substances are consumed
o No sedation or anaesthetic
administered
o Results of patients are generally
consistent
o Patient awake and alert while
receiving stimulation
o No use of X-rays/radioactive
substances
o Researches can manipulate a
damaged brain to measure
effects instead of relying of case
studies
o Extremely invasive procedure,
imposes risk’s that, by todays
ethical standards would be
considered unacceptable
o Involves difficulty in generalising
results
o Can’t be used on individuals who
have any metal implanted/metal
devises in their body or have a
history of seizures
o rTMS cause scalp
pain/headaches in 30% of
patients
o Magnetic field only affects brain
that lies immediately bellow scull
ELECTROENCEPHALOGRAPHY
(EEG)
Assist’s with study of
various brain-related
medical conditions brain damage,
neurological
disorders such as
epilepsy and
Parkinson’s disease.
EEG’s also identity
distinctive patterns
of electrical activity
in the brain often
occurring in people
with depression,
schizophrenia.
Direct stimulation of a specific
brain area controls/involved
with response and may also
disrupt functioning of the
specific area, thereby impairing
the response. Disruptive effect
only apparent when person is
actively engaged in the
behaviour being
disrupted/impaired
Disruptive effect
most evident in
complex
functions such
as language
and memory
PROCEDURE OF
ELECTROENCEPHALOGRAPHY
(EEG)
PRIOR TO THE TREATMENT
Before the EEG, the patient lays
down on the examining table/bed
whilst their scalp is cleaned to
remove any dirt or dead skin in order
to ensure clear detection of the
brains electrical activity. Then the
electrodes are attached to their
scalp
DURING THE TREATMENT
During an EEG, the electrical signals of the brain
are recorded. This electrical activity is detected
by electrodes placed on the patient's scalp and
transmitted to a polygraph that records the
activity. Electrical signals produced by the brain neurons are picked up by the
electrodes and transmitted to a polygraph, where they produce graphs on moving
paper using an ink on a computer screen. The patient may be asked various things such
as to relax and lie first with your eyes open, lay with their eyes closed, to stare at a
flashing light or to breathe deeply and rapidly. All of these activities create changes in
the brain-wave patterns. An EEG can also be performed in a course of night whilst the
patient is asleep for recording a sleep disorder
AFTER THE TREATMENT
After the EEG is performed, the electrodes are removed and the glue that held them in
place is washed off with acetone. The patient is able to go back to normal activities
immediately after and may drive home
ELECTROENCEPHALOGRAPHY
(EEG)
ANDVANTAGES
o
o
o
o
o
Relatively cheap
Fast
Safe
Non invasive procedure
Doesn’t cause pain
LIMITAIONS
o Doesn’t provide detailed
information about which
particular structures of the brain
are activated/what their specific
functions may be
o Difficult to pinpoint specific area
that’s the source of brain wave
activity
o Strength of electrical activity
reduced as a result of needing to
travel through thick brain
structure of the skull
o EEG merely provides a summary
of all the activity of neurons firing
within the brain
COMPUTERISED
TOMOGRAPHY(CT)
CT is a
neuroimaging
technique that
produces a
computerenhanced image of
a cross-section of
the brain from Xrays taken from
different angles
USE CT FOR:
-
Can only be performed by a doctor called a
radiologist. CT rarely has any serious side affects. CT
scanning provides a new way of looking at a live intact
human brain without using invasive and dangerous
procedures. The X-ray procedure of a CT is believed to
be harmless.
http://www.youtube.com/watch?v=dHBUNoMMj6w
Spotting and identifying the precise location and extent of damage to/abnormities in various brain
structures/areas
Research in identifying specific abnormalities in people with mental illnesses
PROCEDURE OF
COMPUTERISED
TOMOGRAPHY(CT)
DURING THE TREATMENT
Patient must lie
extremely still on the
scanner bed with their
head inserted into the
scanner opening. An Xray source slowly moves
circularly around
patients head. An X-ray
detector opposite the
X-ray receives the
information; creating
thin, horizontal crosssectional image of the
brain
PRIOR TO THE TREATMENT
The patient must first be given an injection of iodine in
hand/arm directly into blood stream – used to highlight
the brain’s blood vessels.
AFTER THE TREATMENT
The computer combines all the cross-sectional images
of the brain creating a 2/3 dimensional image of the
brain called a computerised tomogram scan (CT scan)
COMPUTERISED
TOMOGRAPHY(CT)
ADVANTAGES
o
o
Non-invasive procedure
No serious side effects
DISADVANTAGES
o
Doesn’t provide information about
activity (function) of brain, only its
structure
MAGNETIC RESONANCE
IMAGING(MRI)
MRI is a neuroimaging technique that uses
harmless magnetic fields and radio waves to
vibrate atoms in the brain’s neurons to produce
an image of the brain
The vibrations are detected
by a huge magnet in the
chamber surrounding the
motionless person, and are
channelled into a computer.
The computer than
processes the vibrations and
assembles them into a
coloured image that
indicates areas of high and
low brain activity. MRI can
detect and display
extremely small changes in
the brain
MRI measures the vibration of atoms in neurons, it detects if neurons are firing during particular
activities; if atoms are vibrating that means the neurons are firing. Can be used to diagnose unusual
disorders such as Prosopagnosia and Akinetopsia
PROCEDURE OF
MAGNETIC RESONANCE
IMAGING(MRI)
PRIOR TO THE TREATMENT
The patient is directed to
a special self-contained
room where the MRI
machine is located. The
patient will then be asked
to lie down on a
cushioned table, where a
device will be placed
around their head. Then
they will be moved into
the magnet. The
technologist will leave the
room but will stay in
constant contact with the
patient throughout the
entire exam.
DURING THE TREATMENT
When the MRI scan begins, the patient will hear a
muffled thumping sound that will last for several
minutes, while the pictures are being taken. Earplugs or
music will be provided so that the noise doesn't sound
so loud. The patient must lie as still as possible during
the procedure as any movement during this time will
blur the picture.
AFTER THE TREATMENT
After the scanning is complete (generally about 30
minutes) the technologist will return to help the patient
off the table and then they may go home and assume
regular activity
MAGNETIC RESONANCE
IMAGING(MRI)
ADVANTAGES
o
o
o
o
o
o
Enables even more precision in the
study of structure of the live human
brain
Non-invasive
Harmless
Provides more detailed and clearer
images of brain, which are almost
of photographic quality
Doesn’t use X-rays or radioactive
substances
Clearer, more detailed images
than a CT
LIMITATIONS
o
o
It cannot be used with people who
have internal metallic devices such
as heart pacemakers or steel pins in
bones
Like CT its main limitation fro brain
study is that it shows only brain
structure/anatomy and not
function
POSITRON EMISSION
TOMOGRAPHY(PET)
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
Shows structure and
function of brain when
asked certain questions
ie. Count backwards
from 10. This shows the
brains activity and
identifies what each part
of the brains function is
http://www.youtube.com/watch?v=d9iOxMFmPlA
o Dye doesn’t last long
o High quality images
PROCEDURE OF
POSITRON EMISSION
TOMOGRAPHY(PET)
PRIOR TO THE TREATMENT
Patients shouldn’t eat six
hours leading up to the
scan and will be
encouraged to drink a lot
of water. The patient is
taken into an injection
room, where the
radioactive dye is
administered as an
intravenous injection. It will
take around 60 minutes
for the substance to travel
through your body and
accumulate in the tissue
under study.
DURING THE TREATMENT
During the PET procedure, the patient will lay on a bed
which slides into the machine. The patient must lye as
still as possible for the scan to be clear
POSITRON EMISSION
TOMOGRAPHY(PET)
ADVANTAGES
o
o
o
Enables detailed images of the
functioning brain; that is a brain as
its performing tasks
People without brain damage can
be used in research studies
Colour coding of PET scans makes
it relatively simple to identify area
of the brain that are active and
inactive
DISADVANTAGES
o
o
Researcher cannot determine
whether an active brain area is
actually involved in mental
processes or behaviour under
investigation
PET doesn’t necessarily pick up the
very rapid progression/changes in
brain activity because it needs a 40
second interval between scans,
each of which go for 30 seconds
SINGLE PHOTON EMISSION
COMPUTED TOMOGRAPHY(SPECT)
SPECT uses longer-lasting
radioactive tracer and a
scanner to record data that a
computer uses to construct
two/three dimensional images
of active brain regions
o
o
o
Brain disorders – including stroke, seizure and Alzheimer’s disease
Heart problems – including chest pain, heart attack and arterial
blockages in the heart
Various forms of cancer – such as primary tumours and those that
have spread to other parts of the body (metastasized)
Detects Oxygen in brain. More O2 the more activity in that brain region. Used
for longer lasting tasks ie. Counting backwards from 100
PROCEDURE OF
SINGLE PHOTON EMISSION
COMPUTED TOMOGRAPHY(SPECT)
PRIOR TO THE TREATMENT
The radioactive substance
will be administered to
you through an injection
or an intravenous (IV)
infusion into one of the
veins in your arm.
Prior to the scan, you may
have to lie down quietly in
a room for around 15
minutes or more to allow
proper absorption of the
radioactive substance
DURING THE TREATMENT
The health care team members will position the patient
on a table in the room where your SPECT scan test is to
be conducted. A large circular device, a SPECT
machine has a special camera known as a gamma
camera that measures the amount of radioactive
substance absorbed by the patient’s body. The SPECT
machine will rotate around the patient during the scan
while the patient is lying on the table. It then shoots
pictures of organs and other internal structures in the
patient’s brain. The pictures are then processed by a
computer to generate 3-D images of the body
AFTER THE TREATMENT
In just a few hours after the SPECT scan, most of the
radioactive substance is flushed out by the body
through the urine
SINGLE PHOTON EMISSION
COMPUTED TOMOGRAPHY(SPET)
PROS
o
o
o
Can be combined with CT
scanning for better results
Non-invasive
Longer lasting
CONS
o
o
SPECT images not a good quality
as PET
Lower resolution images therefore
not as clear or detailed
FUNCTIONAL MAGNETIC
RESONANCE IMAGING(fMRI)
fMRI is a neuroimaging technique that enables the
identification of the brain areas that are particularly
active during a given task by detecting changes in
oxygen levels in the blood flowing trough the brain
MRI measures oxygen levels in certain areas of the brain to
determine what parts of the brain are being used and what
neural pathways are being used
FUNCTIONAL MAGNETIC
RESONANCE IMAGING(fMRI)
PROS
o
o
o
o
Doesn’t use radiation
Virtually no risks
Easy to use
High resolution images
CONS
o
o
o
Expensive
fMRI can only look at blood flow in
the brain. It can't home in on the
activities of individual nerve cells
(neurons), which are critical to
mental function
can be difficult to interpret

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