Research Methods

Question 1

What methods are used to observe brain anatomy?

Answer 1

CT and MRI

Question 2

What functioning brain imaging methods are used?

Answer 2

PET and fMRI

Question 3

List the four kinds of electromagnetic brain research methods:

Answer 3

1. Single cell
2. EEG
3. ERP
4. MEG

Question 4

Optical imaging types:

Answer 4

Fast and slow

Question 5

Method for modulating brain activity

Answer 5

TMS

Question 6

How is Positron Emission Tomography performed?

Answer 6

A radioactive substance is injected into the body - the researchers observe what parts of the brain use which molecules. It relies on the use of high energy ionizing radiation. The distribution of neurotransmitter binding is examined, providing levels of brain metabolism.

Question 7

What are the pros and cons of PET scans?

Answer 7

+ Assess many aspects of physiological function
+ Provides infor on neurotransmitter binding
+ Allows for good comparison between sample groups
- Involves the use of ionizing radiation, so cannot be used in a long term study
- Poor resolution picture
- Images are averaged over a time that is longer than the thought process

Question 8

How does Computerized Tomography work?

Answer 8

It scans the brain, creating a black and white image. The scan makes use of brain density. Black: cerebrospinal fluid < brain tissue < blood < bone : White. Hemorrhages appear lighter, due to the excess of blood.

Question 9

What are the pros and cons of CT scans?

Answer 9

+ Inexpensive
+ Can be used on almost everyone
- Poor resolution
- Use of ionizing radiation, cannot be used over long studies

Question 10

How does a Magnetic Resonance Imaging process work?

Answer 10

Magnetic fields are used to distort the bahaviour of the protons - the time it takes for the protons to return to recover from distortion creates the image.

Question 11

What are the pros and cons of MRI?

Answer 11

+ It can be used to detect different substances
+ Allows white matter tracts to be visualized via diffusion tensor imaging
+ Does not involve radiation
+ Good spatial resolution
- Can induce claustraphobia
- Cannot be used with individuals with metal not attached to hard tissue
- Expensive

Question 12

What is Diffuse Tensor Imaging?

Answer 12

It shows the direction along which water diffuses in the nerve fibres.
Direction of the water = direction of the connections
Degree of water diffusion = structural integrity of the tracts

Question 13

What is DTI often used for?

Answer 13

Investigating demyelination disorders, examining the changes in white matter tracts.

Question 14

How does Functional Magnetic Resonance Imaging work?

Answer 14

It focuses on the property differences between oxygenated and deoxygenated blood - neuronal activity changes are accompanied by changes in blood flow and oxygen.

Question 15

What are the pros and cons of fMRI?

Answer 15

+ Provides good spatial resolution (NB for surgery)
+ Non-invasive
+ Measures activity within seconds
+ No long lasting side effects, can be performed on the same person many times
+ Widely available
- Cannot be used with people with metal
- There’s no absolution in the nature of blood flow, it’s results are limited
- It doesn’t provide precise info on location of substances

Question 16

How does Single Cell research work?

Answer 16

An electrode is placed into the brain region of interest, then the electrical output of the cells is measured. This establishes the baseline speed of the cell, and we can discover what stimuli cause it to fire at a different rate.

Question 17

Pros and cons of Single Cell

Answer 17

+ Provides info on stimulus type for a cell’s response

- Unethical for humans, for most cases.

Question 18

Explain Electroencephalography

Answer 18

Electric signals are recorded by metal electrodes positioned on the scalp

Question 19

What is associated with the electric activity of the brain? (3)

Answer 19

1. Different states of consciousness (frequency of alpha, beta, gamma waves)
2. Epilepsy (neurons fire in large quantities)
3. Experimental questions (e.g. is alpha suppression present in depression?)

Question 20

Pros and cons of EEG

Answer 20

+ Provides general info on the person’s state
+ Non invasive
+ Excellent temporal solution
- Difficult to detect the source of activity
- Difficult to detect activity of the cells orientation parallel to the brain’s surface

Question 21

Event Related Recordings method

Answer 21

Dipoles are recorded in the form of wave length and currents with positive and negative ends. It gives info about the time course with which info is processed by the brain.

Question 22

Two components in ERPs

Answer 22

1. Exogenous - linked to the physical characteristics of a stimulus; occur early in the wave form
2. Endogenous- driven by internal cognitive states that are independent of stimulus characteristics

Question 23

Pros and cons of ERP

Answer 23

+ Provides info on specific psychological processes, like memory and attention
+ Non invasive
+ Excellent temporal resolution
- Difficult to determine the source of the activity

Question 24

How does Magnetoencephalography work?

Answer 24

Magnetic potential produced by brain activity is recorded

Question 25

What is MEG used for? (3)

Answer 25

1. Locating the source of epileptic activity 2. Location primary cortices so they can be avoided in surgery 3. Understanding cognitive processes in neurologically intact individuals and those with schizophrenia

Question 26

Pros and cons of MEG

Answer 26

+ Provides better info about the source of the activity + Not as susceptible to differences in conduction of tissue intervening between brain and skull - Elaborative set up - Cannot detect cells radial to the brain's surface

Question 27

How does Optical Imaging work?

Answer 27

A laser source of near infrared light is positioned on the scalp and optic fibre bundles are placed a few centimeters from the light source. It's used to measure time course and the source of neural activity

Question 28

Fast vs Slow Optical Imaging

Answer 28

Fast: Optic fibre detects how the path is altered through scattering, the changes are associated with neuronal firing Slow: Optic fibre detect how the path is altered by absorption, looking at oxygenation and deoxygenation of the blood

Question 29

Pros and cons of Fast Optical Imaging

Answer 29

+ Non invasive + Inexpensive + Portable + Detects a neuronal response, not a blood based one - Cannot provide structural info on subcortical regions

Question 30

Pros and cons of Slow Optical Imaging

Answer 30

+ Non invasive + Inexpensive + Portable + Allows for separate calculations for concentration of oxygenated and deoxygenated blood - Cannot provide structural info on subcortical regions - Works with blood, not neuronal response

Question 31

How does Transcranial Magnetic Stimulation work?

Answer 31

A pulsed magnetic field is created over the scalp, which indues an electric field - this alters the pattern of activity in the brain, in the underlying tissue. It can induce and disrupt brain activity.

Question 32

Pros and cons of TMS

Answer 32

+ Confirms lesion findings + Used in therapeutic treatment for clinical syndromes + Gives info on brain reorganization and functional connectivity + Determines cause of deficit: Dysfunction vs disconnection - Small, but possible adverse effects on brain functioning - Only works on regions close to the surface - Doesn't allow for precise localization of effects

Question 33

Techniques for analyzing brain behavior (4)

Answer 33

1. Neuropsychological assessment - looks at the degree to which damage to the CNS may have compromised cognitive functioning 2. Neuropsychological test battery - a compilation of tests ranging from sensory ability to reason and memory 3. Estimate of premorbid functioning - a reasonable guess as to how well an individual was performing before the injury 4. Customized neuropsychological assessment

Question 34

Techniques for assessing brain behaviour relations

Answer 34

1. Neural networks - Created to test theories of neuropsychological functioning and derive general principles regarding brain-behaviour relationships 2. Computational methods - Simulate mental functioning in humans after brain damage, on a computer. This allows for manipulation that isn't possible in humans.