Neuroscience methods for physiological psychology

Question 1

what does MRI stand for?

Answer 1

magnetic resonance imaging

Question 2

what the 2 types of MRI?

Answer 2

• structural MRI
• functional MRI

Question 3

what are the goals of structural imaging with non-invasive methods?

Answer 3

• to study anatomy
• to identify abnormalities (as in brain disease)
• to follow development (childhood to old age)
• to show plasticity

Question 4

what do CT structural MRI scans rely on?

Answer 4

contrast between tissue types (for example, between white matter, gray matter and cerebrospinal fluid)

Question 5

Brain plasticity after motor learning, Draganski et al. (2004)

Answer 5

• healthy ps had to practice a difficult task (juggling) over a series of months
• ps underwent 3 sessions of structural MRI: one before learning to juggle, one after three months without practice
• scan 1 show baseline grey matter before learning, san 2 shows and increase in grey matter by 3 % after 3 months of learning, and after three months without practice grey matter is still 2% above baseline.

Question 6

how do you generate structural MR contrast?

Answer 6

• soft tissue has high water content which has abundant in rotatory motion in random orientation
• magnetic field produced by the magnet cause the protons to become aligned to the magnetic field
• when the radiofrequency coil emits a radiofrequency pulse, the net magentisation vector is turned into an orientation perpendicular to the external magnetic field
• after the radiofrequency pulse the vector of net magnetization returns to the direction of the external magnetic field, during this stage an MR signal is measured
• MR signal is measured during spin-lattice relaxation at a suitable timepoint,, then structural contrast can be established between tissue and cerebrospinal fluid,
• MRI protocols that are based on tissue-specific differences in spin-lattice relaxation are referred to as T1-weighted imaging.

Question 7

what are the goals of fMRI?

Answer 7

to identify brain areas that support sensory and cognitive processes, and to derive models of brain function

Question 8

why is contrast NEEDED for fMRI?

Answer 8

separates non-activated from activated tissue

Question 9

what is T2* contrast in fMRI?

Answer 9

• depends on balance of deoxygenerated to oxygenerated hemoglobin (Hb) within blood in a voxel
• this in turn depends on local regulation of arterial width
• during local neuronal activation flow is increased, more oxy-Hb in capillaries
• oxy-Hb is diamagnetic (does not affect local magnetic field) whereas deoxy-Hb os paramagnetic, making field inhomogeneous
• in inhomogeneous field, horizontal magnetization decays faster (T2* decay)
• slower T2* decay: increased MR signal intensity = blood oxygen level dependent (BOLD) effect
• BOLD signal as an indirect measure of neural activity

Question 10

what os the BOLD effect?

Answer 10

the blood oxygen level dependent effect

Question 10

what are some advantages of combining activation maps of multiple participants?

Answer 10

• allows for further analysis at a group level, leading ti pattern of activation
• to label the location of activation by comparison with a brain atlas

Question 11

what are some disadvantages of fMRI?

Answer 11

• fMRI analysis had low power
• null results are almost impossible to analyse
• statistical maps depend on amplitude and noise

Question 12

What is association?

Answer 12

damage to a single brain brain region, but multiple deficits in behavioural tasks

Question 13

what is dissociation?

Answer 13

damage that leads to impaired performance in task A but performance in task B is normal

Question 14

what is simultanagnosia in Balint’s syndrome?

Answer 14

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

Question 15

what is oculomotor in Balint’s syndrome?

Answer 15

a failure to make certain eye movements