BRAIN RESEARCH METHODS

AMY COOPER

GLOSSARYPG 15 – Pros and Cons of MRIPG 16 – Positron Emission Tomography (PET)PG 17 – Procedure of PETPG 18 – Pros and Cons of PETPG 19 – Single Photon Emission Computed Tomography (SPECT)PG 20 – Procedure of SPECTPG 21 – Pros and Cons of SPECTPG 22 – Functional Magnetic Resonance Imaging (fMRI)PG 23 – Pros and Cons of fMRI

PG 1 – Direct Brain StimulationPG 2 – Electrode StimulationPG 3 – Direct Brain StimulationPG 4 – Transcranial Magnetic Stimulation (TMS)PG 5 – Procedure of TMS PG 6 – Pros and Cons of TMSPG 7 – Electroencephalography (EEG)PG 8 – Procedure of EEGPG 9 – Pros and Cons of EEGPG 10 – Computerised Tomography (CT)PG 11 – Procedure of CTPG 12 – Pros and Cons of CTPG 13 – Magnetic Resonance Imaging (MRI)PG 14 – Procedure of MRI

Can be done by using electrode or pulses of transcranial magnetic

stimulation

DIRECT BRAIN 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

Using device that emits a weak electric current to activate/disrupt the normal activity of neurons in specific brain area’s

ELECTRODE STIMULATIONElectrode is a

small, electrified fine wire which is

inserted into/placed onto a

specific area of the brain

Electrode used to deliver a precisely regulated electric current to the brain area stimulating a specific brain area

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

STIMULATION OF:Occipital Lobe – patients reported seeing flickering lights, spots and coloursAuditory Cortex – ‘hearing’ doorbells, car engines Somatosensory Cortex – ‘feeling’ a tingling sensation in various parts of the bodyPrimary Motor Cortex – patients responded by moving specific body parts

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 brain-stimulation 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 PERIODThe 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

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

DURING THE TREATMENTDuring 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

PROCEDURE OF TRANSCRANIAL MAGNETIC STIMULATION(TMS)PRIOR TO THE TREATMENTThe 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

ADVANTAGESo Effective and reliable technique of

brain researcho Non-invasive procedureo No substances are consumedo No sedation or anaesthetic

administeredo Results of patients are generally

consistent o Patient awake and alert while

receiving stimulationo No use of X-rays/radioactive

substanceso Researches can manipulate a

damaged brain to measure effects instead of relying of case studies

LIMITAIONSo 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

TRANSCRANIAL MAGNETIC STIMULATION(TMS)

ELECTROENCEPHALOGRAPHY(EEG)

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

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.

PROCEDURE OF ELECTROENCEPHALOGRAPHY(EEG)

AFTER THE TREATMENTAfter 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

DURING THE TREATMENTDuring 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

PRIOR TO THE TREATMENTBefore 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

ANDVANTAGESo Relatively cheapo Fasto Safe o Non invasive procedureo Doesn’t cause pain

LIMITAIONSo 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

ELECTROENCEPHALOGRAPHY(EEG)

COMPUTERISED TOMOGRAPHY(CT)

http://www.youtube.com/watch?v=dHBUNoMMj6w

CT is a neuroimaging technique that produces a computer-enhanced image of a cross-section of the brain from X-rays taken from different angles

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.

USE CT FOR:- 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

COMPUTERISED TOMOGRAPHY(CT)PROCEDURE OF

AFTER THE TREATMENTThe 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)

DURING THE TREATMENTPatient must lie extremely still on the scanner bed with their head inserted into the scanner opening. An X-ray source slowly moves circularly around patients head. An X-ray detector opposite the X-ray receives the information; creating thin, horizontal cross-sectional image of the brain

PRIOR TO THE TREATMENTThe patient must first be given an injection of iodine in hand/arm directly into blood stream – used to highlight the brain’s blood vessels.

COMPUTERISED TOMOGRAPHY(CT)

ADVANTAGESo Non-invasive procedureo No serious side effects

DISADVANTAGESo 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

MAGNETIC RESONANCE IMAGING(MRI)PROCEDURE OF

AFTER THE TREATMENTAfter 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

DURING THE TREATMENTWhen 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.

PRIOR TO THE TREATMENTThe 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.

ADVANTAGESo Enables even more precision in

the study of structure of the live human brain

o Non-invasiveo Harmlesso Provides more detailed and

clearer images of brain, which are almost of photographic quality

o Doesn’t use X-rays or radioactive substances

o Clearer, more detailed images than a CT

LIMITATIONSo It cannot be used with people who

have internal metallic devices such as heart pacemakers or steel pins in bones

o Like CT its main limitation fro brain study is that it shows only brain structure/anatomy and not function

MAGNETIC RESONANCE IMAGING(MRI)

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 longo High quality images

PROCEDURE OF POSITRON EMISSION TOMOGRAPHY(PET)

DURING THE TREATMENTDuring 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

PRIOR TO THE TREATMENTPatients 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.

ADVANTAGESo Enables detailed images of the

functioning brain; that is a brain as its performing tasks

o People without brain damage can be used in research studies

o Colour coding of PET scans makes it relatively simple to identify area of the brain that are active and inactive

DISADVANTAGESo Researcher cannot determine

whether an active brain area is actually involved in mental processes or behaviour under investigation

o 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

POSITRON EMISSION TOMOGRAPHY(PET)

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

SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY(SPECT)

Detects Oxygen in brain. More O the more activity in that brain region. Used for longer lasting tasks ie. Counting backwards from 1002

o Brain disorders – including stroke, seizure and Alzheimer’s diseaseo Heart problems – including chest pain, heart attack and arterial

blockages in the hearto Various forms of cancer – such as primary tumours and those that

have spread to other parts of the body (metastasized)

PROCEDURE OF SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY(SPECT)

AFTER THE TREATMENTIn just a few hours after the SPECT scan, most of the radioactive substance is flushed out by the body through the urine

DURING THE TREATMENTThe 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

PRIOR TO THE TREATMENTThe 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

PROSo Can be combined with CT

scanning for better resultso Non-invasiveo Longer lasting

CONSo SPECT images not a good quality

as PETo Lower resolution images therefore

not as clear or detailed

SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY(SPET)

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

PROSo Doesn’t use radiationo Virtually no riskso Easy to useo High resolution images

CONSo Expensiveo 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

o can be difficult to interpret

FUNCTIONAL MAGNETIC RESONANCE IMAGING(fMRI)