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BRAIN RESEARCH METHODS

Monday, 22 February 2010

BRAIN RESEARCH METHODS

BRAINS ARE HARD TO STUDY BECAUSE THEY ARE SURROUNDED BY A SCULL

IN THE PAST RESEARCH’S USED THE BRAINS OF DEAD PEOPLE AND ANIMALS. BUT THIS HAD MAJOR LIMITATIONS!!

RESEARCH’S ALSO USED LIVING ANIMALS BUT THIS WAS HIGHLY UNETHICAL.

IT HAS ONLY BEEN IN THE LATER HALF OF THE 20TH CENTURY THAT RESEARCH’S HAVE HAD THE TECHNOLOGY TO STUDY THE BRAIN EFFECTIVELY AND ETHICALLY.


CASE STUDIES

WE CAN’T GO BUSTING HEADS IN ORDER TO SEE WHAT HAPPENS TO THE BRAIN. THIS IS UNETHICAL!

THE ETHICAL WAY TO GO ABOUT STUDYING A PERSON WITH SOME DAMAGE TO THEIR BRAIN IS TO WAIT FOR THEM TO HAVE AN ACCIDENT AND THEN HOPE THEY ARE PREPARED TO ALLOW YOU TO STUDY THEM.

STUDYING MEANS DOING ALL SORTS OF MEASUREMENTS LIKE, DIAGNOSTIC TESTS, INTERVIEWS, OBSERVATIONS, AND LOOKING AT MEDICAL RECORDS


ADVANTAGES

• LOTS OF INDEPTH DETAIL

• RICH AMOUNT OF INFO

LIMITATIONS

• TAKE A LONG TIME TO GET INFORMATION

• INDIVIDUAL DIFFERENCES ARE NOT MEASURED

• PLASTICITY - THE BRAIN CAN ADAPT TO

• AS THEY ARE QUITE UNIQUE TO THE INDIVIDUAL, THE RESULTS CAN’T BE GENERALISED FAIRLY


ELECTRICAL STIMULATION OF THE BRAIN (ESB)

ELECTRICAL STIMULATION OF THE BRAIN INVOLVES USING AN ELECTRODE TO DELIVER AN ELECTRIC CURRENT TO THE BRAIN, THEN THAT PART OF THE BRAIN THAT RECEIVES THE CURRENT RESPONDS ACCORDINGLY.

EXAMPLE: STIMULATING THE HYPOTHALAMUS IN ANIMALS EVOKES FEEDING, DRINKING, SEXUAL AROUSAL AND AGGRESSION DEPENDING ON THE AREA STIMULATED


ADVANTAGES

• CAN PINPOINT LOCATION AND FUNCTION OF CERTAIN BRAIN STRUCTURES. • CAN HELP IDENTIFY HEMISPHERIC SPECIALISATION

LIMITATIONS

• EXTREMELY INVASIVE - MUST APPLY DIRECTLY TO THE BRAIN

• CRUDE - NOT EASY TO TELL HOW FAR THE STIMULATION HAS SPREAD

• CAN’T ALWAYS BE GENERALISED TO ALL PEOPLE, AS ESB IS USUALLY DONE ON NOT PROPERLY FUNCTIONING BRAINS

• CAN ONLY BE USED ON THOSE UNDERGOING BRAIN SURGERY


ELECTROENCEPHALOGRAPH (EEG)

THE EEG MEASURES ELECTRICAL ACTIVITY IN LOCALISED AREAS OF THE BRAIN. ELECTRODES ARE ATTACHED TO THE SURFACE OF THE SCALP AND THE ACTIVITY OF THE NEURONS ARE MEASURED.


ADVANTAGES

• NON-INVASIVE

• INEXPENSIVE AND SAFE CAN BE USED ON EVERYONE

• CAN BE USED TO MEASURE OVER A LONG PERIOD OF TIME EG. SLEEP

DISADVANTAGES

• GENERAL MEASURE OF ACTIVITY

• NOT AN IMAGING TECHNIQUE

• SKULL CAN INTERFERE WITH ELECTRODE READING


COMPUTERISED TOMOGRAPHY (CT OR CAT )

CAT SCANS WERE THE FIRST NEURO-IMAGING TECHNIQUES

CAT SCANS TAKE A NUMBER OF X-RAYS FROM DIFFERENT ANGLES TO PRODUCE A COMPTUTER IMAGE OF SLICES OF THE BRAIN


ADVANTAGES

• NON-INVASIVE

• PROVIDE VERY DETAILED IMAGE OF LIVING BRAIN

• CAN FORM 3D IMAGE

DISADVANTAGES

• WILL ONLY SHOW STRUCTURE AND NOT FUNCTION

• EXPENSIVE AND NEEDS HIGHLY QUALIFIED STAFF

• MUST REMAIN STILL IN AN ENCLOSED SPACE


POSITRON EMISSION TOMOGRAPHY

A PET CONSTRUCTS A COMPUTER IMAGE OF BRAIN FUNCTION AND ACTIVITY. IT IS USED TO VIEW COGNITIVE AND BEHAVIORAL ACTIVITY WHEN PATIENTS ARE GIVEN A RANGE OF TASKS. RED INDICATES AREAS OF HIGH ACTIVITY, WHERE AS PURPLE INDICATES AREAS OF LOW ACTIVITY. A HARMLESS RADIOACTIVE SUBSTANCE IS INJECTED INTO THE PATIENT WHICH EMITS SIGNALS WHEN PRESENT IN THE BRAIN. A COMPUTER THEN READS THIS INFORMATION TO HELP COLOUR CODE THE IMAGE.


ADVANTAGES

• YOU CAN SEE HOW THE BRAIN FUNCTIONS

• YOU CAN SEE WHICH WHICH AREAS OF THE BRAIN ARE ACTIVE FOR CERTAIN TYPES OF TASKS

• COLOR CODE MAKES THINGS EASY TO UNDERSTAND

LIMITATIONS

• NEED TO INJECT RADIOACTIVE MATERIAL INTO THE PERSON, SO SESSIONS MUST BE KEPT SHORT

• ONLY ABLE TO VIEW THE BRAIN FOR A SHORT PERIOD OF TIME, AS IT TAKES 30 SECONDS TO SCAN AND YOU MUST REST FOR 40 SECONDS BETWEEN SCANS


MAGNETIC RESONANCE IMAGING

MAGNETIC AND RADIO WAVES BOUNCE OFF NEURONS IN THE BRAIN AND THESE VIBRATIONS ARE DETECTED BY A HUGE MAGNET IN THE MACHINE AND FED INTO A COMPUTER. THE COMPUTER THEN PROCESSEs THIS INFO AND CREATES A COLOUR CODED 3D IMAGE. IT IS MORE DETAILED THAN A CT SCAN.

IT IS USED TO DIAGNOSE STRUCTURAL ABNORMALITIES AND SMALL CHANGES OVER TIME. FOR EXAMPLE YOU CAN STUDY THE BRAIN OF A SCHIZOPHRENIA PATIENT AND LOOK THE BRAIN CELLS CHANGE OVER TIME. IT IS MORE EXACT THAN A CT SCAN.


ADVANTAGES

• NON INVASIVE

• DETAILED AND CLEAR IMAGES OF THE BRAIN.

LIMITATIONS

• THE INABILITY TO USE IT ON PEOPLE WITH METAL IN THEIR BODIES

• DOES NOT SHOW YOU THE FUNCTIONING ON THE BRAIN.

• CONFINED SPACE A PROBLEM


FUNCTIONAL MAGNETIC RESONANCE IMAGING (FMRI)

THE FMRI SHOWS HOW THE BRAIN IS FUNCTIONING BY MONITORING THE LEVELS OF OXYGEN IN THE BRAIN. THE HIGHER THE FUNCTIONING, THE HIGHER THE BLOOD FLOW.

THE MAJOR DIFFERENCE BETWEEN AN FMRI AND A PET IS THAT IT CAN PICK UP CHANGES RAPIDLY, OVER SECONDS AS OPPOSED TO MINUTES. FMRI HAS ALSO BECOME 3D IN RECENT YEARS.


ADVANTAGES

• NO RADIATION

• SHOWS FUNCTIONING OF BRAIN

• COLOUR CODING MAKES IT EASY TO UNDERSTAND

• CAN TRACK BRAIN CHANGES MOMENT TO MOMENT

LIMITATIONS

• ACTIVITY MAY BE A RESULT OF SOMETHING ELSE, OTHER THAN THE TASK GIVEN


CLARIFICATIONS

INVASIVE: IN RELATION TO BRAIN RESEARCH, ANY TECHNIQUE THAT INVOLVES OPENING THE BRAIN UP.

DIFFERENCE BETWEEN PET AND CT INJECTIONS.

• CT - THE PARTICIPANT MUST BE INJECTED WITH A SUBSTANCE IN THE ARM OR HAND. THE SUBSTANCE IS BASED ON IODINE AND IS NOT RADIOACTIVE

• PET - PRIOR TO THE PROCEDURE A RADIOACTIVE SUBSTANCE IS IS INJECTED INTO THE PATIENTS BLOOD VESSEL.


PRACTICE EXAM QUESTIONS



Arthur has agreed to participate in a research study. In the study a small amount of radioactive substance will be injected into his blood vessels and transported to his brain. At the same time as the injection he will be asked to think of as many words as he can beginning with the letter L.



Arthur has agreed to participate in a research study. In the study a small amount of radioactive substance will be injected into his blood vessels and transported to his brain. At the same time as the injection he will be asked to think of as many words as he can beginning with the letter L.What is this recording procedure known as?



Arthur has agreed to participate in a research study. In the study a small amount of radioactive substance will be injected into his blood vessels and transported to his brain. At the same time as the injection he will be asked to think of as many words as he can beginning with the letter L.What is this recording procedure known as?A. EEG



Arthur has agreed to participate in a research study. In the study a small amount of radioactive substance will be injected into his blood vessels and transported to his brain. At the same time as the injection he will be asked to think of as many words as he can beginning with the letter L.What is this recording procedure known as?A. EEGB. PET



Arthur has agreed to participate in a research study. In the study a small amount of radioactive substance will be injected into his blood vessels and transported to his brain. At the same time as the injection he will be asked to think of as many words as he can beginning with the letter L.What is this recording procedure known as?A. EEGB. PETC. CT



Arthur has agreed to participate in a research study. In the study a small amount of radioactive substance will be injected into his blood vessels and transported to his brain. At the same time as the injection he will be asked to think of as many words as he can beginning with the letter L.What is this recording procedure known as?A. EEGB. PETC. CTD. MRI


Arthur has agreed to participate in a research study. In the study a small amount of radioactive substance will be injected into his blood vessels and transported to his brain. At the same time as the injection he will be asked to think of as many words as he can beginning with the letter L.

What is this recording procedure known as?A. EEGB. PETC. CTD. MRI

Answer: B. PET


The brain scanning methods that provide the most comprehensive information on the functioning brain are _________ and __________. A. PET; fMRI B. CT; MRI C. MRI; fMRI D. CT; PET


The brain scanning methods that provide the most comprehensive information on the functioning brain are _________ and __________. A. PET; fMRI B. CT; MRI C. MRI; fMRI D. CT; PET

Answer: A. PET; fMRI


One disadvantage of using an electroencephalograph (EEG) to investigate the brain is that


One disadvantage of using an electroencephalograph (EEG) to investigate the brain is that A. it cannot be used with a range of patients such as infants.


One disadvantage of using an electroencephalograph (EEG) to investigate the brain is that A. it cannot be used with a range of patients such as infants. B. it is invasive.


One disadvantage of using an electroencephalograph (EEG) to investigate the brain is that A. it cannot be used with a range of patients such as infants. B. it is invasive. C. it does not provide detailed information about brain function compared to positron emission tomography (PET).


One disadvantage of using an electroencephalograph (EEG) to investigate the brain is that A. it cannot be used with a range of patients such as infants. B. it is invasive. C. it does not provide detailed information about brain function compared to positron emission tomography (PET). D. it is expensive compared to functional magnetic resonance imaging (fMRI).


One disadvantage of using an electroencephalograph (EEG) to investigate the brain is that A. it cannot be used with a range of patients such as infants. B. it is invasive. C. it does not provide detailed information about brain function compared to positron emission tomography (PET). D. it is expensive compared to functional magnetic resonance imaging (fMRI).

C. it does not provide detailed information about brain function compared to positron emission tomography (PET).


Which of the following is incorrect about computerised tomography (CT) scans? A. CT scans provide information about the function and extent of damage to the brain. B. The risks to the patient associated with CT scans are negligible. C. CT scans usually require an injection into the bloodstream. D. CT scans use X-rays taken at various angles to create an image of the brain.


Which of the following is incorrect about computerised tomography (CT) scans? A. CT scans provide information about the function and extent of damage to the brain. B. The risks to the patient associated with CT scans are negligible. C. CT scans usually require an injection into the bloodstream. D. CT scans use X-rays taken at various angles to create an image of the brain.

A. CT scans provide information about the function and extent of damage to the brain.


A PET scan provides information

A. in very high resolution pictures that show brain structure and function. B. in a colour-coded map that reveals areas of high activity in the brain. C. about abnormalities in the structure of the brain. D. about the number of cognitive tasks that were performed correctly.


A PET scan provides information

A. in very high resolution pictures that show brain structure and function. B. in a colour-coded map that reveals areas of high activity in the brain. C. about abnormalities in the structure of the brain. D. about the number of cognitive tasks that were performed correctly.

B. in a colour-coded map that reveals areas of high activity in the brain.


1. In terms of the potential risks to participants, describe one disadvantage of PET scanning in comparison with CT scanning. (1 mark)



2. If a person has a metallic implant in their body, such as a heart pacemaker or a pin in a bone, they are advised not to undertake a certain brain scanning technique. What is the name of this technique? (1 mark)



The PET scan: • is more invasive

• involves injecting a radioactive substance into the body.

2. If a person has a metallic implant in their body, such as a heart pacemaker or a pin in a bone, they are advised not to undertake a certain brain scanning technique. What is the name of this technique? (1 mark)

MRI or fMRI scanning


In positron emission tomography (PET) scans, a substance is tagged with a radioactive marker and then monitored. This substance is a form of A. iodine. B. kryptonite. C. uranium. D. glucose.

D. glucose.

Which procedure results in a high-quality three-dimensional picture of the brain? A. functional magnetic resonance imaging (fMRI) scan B. electrical stimulation of the brain (ESB) scan C. positron emission topography (PET) scan D. electroencephalograph (EEG) scan

Which two procedures allow researchers to view changes in brain activity over time? A. positron emission topography (PET) scan and computerised tomography (CT) scan B. positron emission topography (PET) scan and functional magnetic resonance imaging (fMRI) scan C. magnetic resonance imaging (MRI) scan and functional magnetic resonance imaging (fMRI) scan D. computerised tomography (CT) scan and magnetic resonance imaging (MRI) scan


a. What information about the brain does positron emission tomography (PET) provide? (1 mark)



the PET scan shows which areas of the brain are active while certain tasks are performed




• the PET scan gives information about brain functioning.





b. When compared to computerised tomography (CT), outline one advantage of using positron emission tomography (PET). (1 mark)





b. When compared to computerised tomography (CT), outline one advantage of using positron emission tomography (PET). (1 mark)Advantages of PET include:






• CT is static while PET shows the brain in action







• CT shows structural features and location of damage while PET shows functional areas








• PET is more sensitive than CT in detecting areas of brain damage









• unlike CT scans, PET scans are colour-coded, which aids interpretation.









• unlike CT scans, PET scans are colour-coded, which aids interpretation.

This question demanded a speci7ic comparison; however, many students mistakenly compared PET scans with other forms of brain‐imaging.


c. What is the difference in the information provided by magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI)? (1 mark)



DIFFERENCES INCLUDE:




• fMRI uses a magnetic field to create a three dimensional image of the brain where any two dimensional slice can be selected, and also displays brain activity on the screen




• fMRI uses a magnetic field to create a three dimensional image of the brain where any two dimensional slice can be selected, and also displays brain activity on the screen

• MRI shows only the structure of the brain.


brain research methods copy

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