L7 & L8 - Methods for Physiological Psychology

Question 1

What are the goals of structural MRI?

Answer 1

Non invasive methods
Study anatomy
Identify abnormalities e.g. brain disease
Follow development e.g. childhood to adulthood
Show plasticity

Question 2

What are the methods of interest to biological psychology?

Answer 2

Computed tomography (CT) scan
Magnetic resonance imaging (MRI)

They both rely on contrast between tissue types: white matter (myelinated axons), grey matter (cortical areas and basil ganglia)

Question 3

What is a practical application of structural MRI for biological psychological?

Answer 3

Juggling
MRI shows clusters of statistically significant expansion of grey matter
This is seen in ps who learn how to juggle
Correspond to visual motion area

Question 4

What is the extrastriate visual area?

Answer 4

Processes input from geniculostriate system
Travels from retina to visual cortex

Question 5

How do you generate structural MR contrast?

Answer 5

Spin of protons when subject or patient outside of the magnetic field
When patient is inside the magnetic field, they all spin vertically
Protons in different tissue types require different time to realign

Question 6

What are the goals of functional MRI?

Answer 6

Identify brain areas that support sensory and cognitive processes
Derive models of brain function
Blood flow
Need contrast the separates non-activated vs activated tissue

Question 7

What are the problems with functional MRI?

Answer 7

How do you measure neural activity in functional contrast
How to generate measurable contrast
How to identify functional contrast in fMRI raw data

Question 8

How do you measure neural activity in functional contrast? BOLD effect

Answer 8

T2 contrast - depends on balance of deoxygenated to oxygenated haemoglobin, depends on local regulation of arterial width
Local neuronal activation - flow is increased, in inhomogeneous field horizontal magnetisation decays faster
BOLD signal as an indirect measure of neural activity

Question 9

What is fMRI temporal resolution?

Answer 9

Poor temporal resolution
24 seconds
2% signal change is tiny

Question 10

What are the different design types in the temporal sequence of stimuli?

Answer 10

Block design - 7x stimulus A, rest, 7x stimulus B etc (no activation of visual cortex during rest, more stimuli=more signal)
Rapid event-related design - random stimulus onset

Question 11

What are the advantages and disadvantages of fMRI block design and event-related design?

Answer 11

Block - advantages: good statistical power, robust, continuous activation - disadvantages: inflexible, limited number of conditions
Event-related designs - advantages: avoids habituation, analyse subtypes of responses such as correct/incorrect - disadvantages: reduced sensitivity to neural events

Question 12

How do you identify areas that show functional contrast?

Answer 12

Stages of fMRI data analysis: images undergo
- motion correction
- categorisation between subjects fMRI and anatomical scans
- normalisation
- statistical analysis on each voxel

Question 13

What are the limitations of talairach-tournoux atlas?

Answer 13

Only one brain
Only one hemisphere
Fixation likely changed shape of brain

Question 14

What are some fMRI statistics?

Answer 14

Analysis has low power - chance of one of these voxels being active at the 0.05 level is high, by chance we expect 6553 voxels, cant control type 1 errors
Null results are almost impossible to interpret - significant results implies a certain brain region is involved with a task
Statistical maps depend on amplitude and noise

Question 15

What are the goals of neuropsychology\/

Answer 15

Relate brain anatomy to behaviour
Localise impaired behaviour to damaged regions
Exclude localisation of preserved skills to damaged regions

Association - damage to a single brain region, but multiple deficits
Dissociation - damage leads to impaired performance in task A but performance in task B is normal

Question 16

What are some examples of studying associations?

Answer 16

Simultanagnosia (only perceived one at a time)
Oculomotor apraxia (failure to make eye movement)
Optic apraxia (inability to reach to seen target)

Question 17

What are studying associations?

Answer 17

Damage to a single brain region, but multiple deficits
Damage to region X leads to deficits in function A, B, C
Inference - tasks A,B,C require same neural circuit
Alternative I - A,B,C may be processed by separate functional regions that are anatomical neighbours
Alternative II - X is a common relay station for anatomically and functionally distinct regions A,B,C

Question 18

What are studying dissociations?

Answer 18

Definition: patient is impaired in one task but performs normally in a different task

Inference - tasks rely on separate networks
Alternative I - impaired task simply more difficult
Alternative II - performance on unimpaired task at ceiling

Question 19

What were the findings of studying double dissociations?

Answer 19

DF, visual agnosia - poor at discriminating shapes, good at visually guided movements

RV, optic ataxia - good at discriminating shapes, poor at visually guided movements