Neuroscience Methods II

Question 1

Application of structural MRI

Answer 1

Study of brain plasticity

Question 2

processes underlying MRI

Answer 2

role of the magnet - Because of the high water content of soft tissue, there are abundant protons which are in rotatory motion

Question 3

how structural contrast in MRI can be generated on the basis of…

Answer 3

increasing longitudinal magnetization after the radiofrequency pulse

Question 4

to identify brain areas that support sensory and cognitive processes, and to derive models of brain function in fMRI we have to overcome

Answer 4

· Problem one: how to measure neural activity in functional contrast?
· Problem two: how to generate measurable functional contrast in an experiment?
· Problem three: how to identify functional contrast in fMRI raw data?

Question 5

How to measure T2* Contrast

Answer 5

depends on contrast of deoxygenated to oxygenated haemoglobin

Question 6

T2* decay also varies with

Answer 6

the functional state of tissue

Question 7

an increased concentration of oxy-hemoglobin…

Answer 7

makes the T2* decay slower, leading to increased MR signal intensity

Question 8

Main components of structural MRI machine

Answer 8

magnet, gradient coils, and radiofrequency coil

Question 9

Limitations for Blood Oxygenation Level Dependent (BOLD) response

Answer 9

participant’s fatigue because it takes a long time to record the necessary number of repeat responses

meaning that the slow BOLD responses to individual stimuli overlap

Question 10

fMRI block design advantages

Answer 10

good statistical power
robust
continuous activation

Question 11

fMRI block design disadvantages

Answer 11

inflexible
limited number of conditions

Question 12

Event-related designs advantages

Answer 12

avoids habituation
analyse subtypes of responses such as correct/incorrect

Question 13

Event-related designs disadvantages

Answer 13

reduced sensitivity to neural events

Question 14

Talairach limitations

Answer 14

based on a single brain and a single hemisphere
based has likely changed in the process of fixation

Question 15

Talairach advantages

Answer 15

procedure for Talairach co-ordinates is highly standardized and can therefore facilitate comparison of results from multiple studies

Question 16

fMRI limitations

Answer 16

fMRI analysis has low power

null results are almost impossible to interpret, in particular null results do not justify a conclusion like “region is not involved with task“

statistical maps depend on amplitude and noise so out of two regions with the same level of activation but different levels of noise one could be labelled as activated, the other as not activated

Question 17

Studying association

Answer 17

Damage to a single brain region, but multiple deficits (in typical combination, as a syndrome)

Question 18

Studying dissociation

Answer 18

Damage leads to impaired performance in task A but performance in task B is normal

Question 19

simultanagnosia

Answer 19

in a visual scene patients can only see one item at a time

Question 20

optic ataxia

Answer 20

the inability to accurately point to or reach for objects under visual guidance with intact ability when directed by sound or touch despite normal strength

Question 21

optic apraxia

Answer 21

inability to turn the eyes voluntarily in a horizontal manner

a failure to make certain eye movements

Question 22

Three symptoms of Balint’s syndrome

Answer 22

simultanagnosia
optic ataxia
optic apraxia